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Background: We describe the use of Apisensr, a web-based application that can be used to implement quantitative bias analysis for misclassification, selection bias, and unmeasured confounding. We apply Apisensr using an example of exposure misclassification bias due to use of self-reported body mass index (BMI) to define obesity status in an analysis of the relationship between obesity and diabetes., Methods: We used publicly available data from the National Health and Nutrition Examination Survey. The analysis consisted of: (1) estimating bias parameter values (sensitivity, specificity, negative predictive value, and positive predictive value) for self-reported obesity by sex, age, and race-ethnicity compared to obesity defined by measured BMI, and (2) using Apisensr to adjust for exposure misclassification., Results: The discrepancy between self-reported and measured obesity varied by demographic group (sensitivity range: 75%-89%; specificity range: 91%-99%). Using Apisensr for quantitative bias analysis, there was a clear pattern in the results: the relationship between obesity and diabetes was underestimated using self-report in all age, sex, and race-ethnicity categories compared to measured obesity. For example, in non-Hispanic White men aged 40-59 years, prevalence odds ratios for diabetes were 3.06 (95% confidence inerval = 1.78, 5.30) using self-reported BMI and 4.11 (95% confidence interval = 2.56, 6.75) after bias analysis adjusting for misclassification., Conclusion: Apisensr is an easy-to-use, web-based Shiny app designed to facilitate quantitative bias analysis. Our results also provide estimates of bias parameter values that can be used by other researchers interested in examining obesity defined by self-reported BMI., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: To identify the association of newly developed prepregnancy overweight and obesity with stillbirth and infant mortality., Methods: We studied subsequent pregnancies of mothers who were normal weight at fertilization of their first identified pregnancy, from a population-based cohort that linked birth registry with death records in Pennsylvania, 2003-2013. Women with newly developed prepregnancy overweight and obesity were defined as those whose body mass index (BMI) before second pregnancy was between 25 and 29.9 or 30 or higher, respectively. Our main outcomes of interest were stillbirth (intrauterine death at 20 weeks of gestation or greater), infant mortality (less than 365 days after birth), neonatal death (less than 28 days after birth) and postneonatal death (29-365 days after birth). Associations of both prepregnancy BMI categories and continuous BMI with each outcome were estimated by nonparametric targeted minimum loss-based estimation and inverse-probability weighted dose-response curves, respectively, adjusting for race-ethnicity, smoking, and other confounders (eg, age, education)., Results: A cohort of 212,889 women were included for infant mortality analysis (192,941 women for stillbirth analysis). The crude rate of stillbirth and infant mortality in these final analytic cohorts were 3.3 per 1,000 pregnancies and 2.9 per 1,000 live births, respectively. Compared with women who stayed at a normal weight in their second pregnancies, those becoming overweight had 1.4 (95% CI 0.6-2.1) excess stillbirths per 1,000 pregnancies. Those becoming obese had 3.6 (95% CI 1.3-5.9) excess stillbirths per 1,000 pregnancies and 2.4 (95% CI 0.4-4.4) excess neonatal deaths per 1,000 live births. There was a dose-response relationship between prepregnancy BMI increases of more than 2 units and increased risk of stillbirth and infant mortality. In addition, BMI increases were associated with higher risks of infant mortality among women with shorter interpregnancy intervals (less than 18 months) compared with longer intervals., Conclusion: Transitioning from normal weight to overweight or obese between pregnancies was associated with an increased risk of stillbirth and neonatal mortality.

While prepregnancy obesity increases risk of stillbirth, few studies have evaluated the role of newly developed obesity independent of long-standing obesity. Additionally, researchers have relied almost exclusively on parametric models, which require correct specification of an unknown function for consistent estimation. We estimated the association between incident obesity and stillbirth in a cohort constructed from linked birth and death records in Pennsylvania (2003-2013). Incident obesity was defined as body mass index (weight (kg)/height (m)2) greater than or equal to 30. We used parametric G-computation, semiparametric inverse-probability weighting, and parametric/nonparametric targeted minimum loss-based estimation (TMLE) to estimate the association between incident prepregnancy obesity and stillbirth. Compared with pregnancies from women who stayed nonobese, women who became obese prior to their next pregnancy were estimated to have 2.0 (95% confidence interval (CI): 0.5, 3.5) more stillbirths per 1,000 pregnancies using parametric G-computation. However, despite well-behaved stabilized inverse probability weights, risk differences estimated from inverse-probability weighting, nonparametric TMLE, and parametric TMLE represented 6.9 (95% CI: 3.7, 10.0), 0.4 (95% CI: 0.1, 0.7), and 2.9 (95% CI: 1.5, 4.2) excess stillbirths per 1,000 pregnancies, respectively. These results, particularly those derived from nonparametric TMLE, were highly sensitive to covariates included in the propensity score models. Our results suggest that caution is warranted when using nonparametric estimators to quantify exposure effects., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: To investigate the association between early-pregnancy weight gain and risk of preeclampsia to inform pregnancy weight gain recommendations., Study Design: We performed a case-cohort study using a hospital database including 80,812 singleton deliveries from Magee-Womens Hospital, Pittsburgh, Pennsylvania (1998-2011). In each of 6 prepregnancy body mass index (BMI) groups, we abstracted serial antenatal weight measurements from the records of up to 339 preeclampsia cases and 1254 randomly selected pregnancies. Early gestational weight gain (16-19 weeks' gestation) was standardized for gestational duration using BMI-specific z-score charts. Multivariable log-binomial regression was used to assess the association between weight gain z-score and risk of preeclampsia. We determined the impact of preeclampsia misclassification using probabilistic bias analysis., Main Outcome Measure: Risk of preeclampsia., Results: For normal weight women, there was a steady increase in preeclampsia risk with increasing early gestational weight gain z-score. For example, compared with a weight gain of 1.2 kg (z-score = -1 SD), a 7.2-kg weight gain (z-score = +1 SD) at 16 weeks was associated with 1.3 (0.50, 2.2) excess preeclampsia cases per 100 deliveries. Weight loss at 16-19 weeks among grade 2 or 3 obese women was associated with a reduced risk of preeclampsia. Associations were null among overweight and grade 1 obese women. The bias analysis supported the validity of the conventional analysis., Conclusions: Early-pregnancy weight gain may be associated with preeclampsia in some BMI groups. Future revisions of pregnancy weight gain recommendations should account for preeclampsia risks from this and additional studies., (Copyright © 2018 International Society for the Study of Hypertension in Pregnancy. Published by Elsevier B.V. All rights reserved.)

Weight gain in early pregnancy may influence a woman's risk of developing preeclampsia. However, the consequences of weight gain throughout pregnancy up to the diagnosis of preeclampsia are unknown. The aim of this study was to determine whether pregnancy weight gain before the diagnosis of preeclampsia is associated with increased risks of preeclampsia (overall and by preeclampsia subtype). The study population included nulliparous pregnant women in the Swedish counties of Gotland and Stockholm, 2008 to 2013, stratified by early pregnancy body mass index category. Electronic medical records were linked with population inpatient and outpatient records to establish date of preeclampsia diagnosis (classified as any, early preterm <34 weeks, late preterm 34-36 weeks, or term ≥37 weeks). Antenatal weight gain measurements were standardized into gestational age-specific z scores. Among 62 705 nulliparous women, 2770 (4.4%) developed preeclampsia. Odds of preeclampsia increased by ≈60% with every 1 z score increase in pregnancy weight gain among normal weight and overweight women and by 20% among obese women. High pregnancy weight gain was more strongly associated with term preeclampsia than early preterm preeclampsia (eg, 64% versus 43% increased odds per 1 z score difference in weight gain in normal weight women, and 30% versus 0% in obese women, respectively). By 25 weeks, the weight gain of women who subsequently developed preeclampsia was significantly higher than women who did not (eg, 0.43 kg in normal weight women). In conclusion, high pregnancy weight gain before diagnosis increases the risk of preeclampsia in nulliparous women and is more strongly associated with later-onset preeclampsia than early-onset preeclampsia., (© 2018 American Heart Association, Inc.)

Objective: To investigate relationships between weight resilience (maintaining a normal weight in a food desert environment) and fruit and vegetable (F&V) intake, attitudes and barriers., Design: Cross-sectional, in-person surveys collected May-December 2011, including self-reported data on F&V-related psychosocial factors, attitudes and barriers. Two 24 h dietary recalls were completed; weight and height were measured. Multivariable regression models estimated prevalence ratios (95 % CI)., Setting: Two low-income, predominantly African-American food deserts in Pittsburgh, Pennsylvania, USA., Subjects: Women aged 18-49 years (n 279) who were the primary food shopper in a household randomly selected for a parent study., Results: Fifteen per cent were weight resilient, 30 % were overweight and 55 % were obese. Overall, 25 % reported eating ≥5 F&V servings/d. After adjustment for age, education, parity, employment, living alone, physical activity, per capita income and mean daily energy intake, women eating ≥5 F&V servings/d were 94 % more likely to be weight resilient compared with those eating <5 servings/d (1·94; 1·10, 3·43). Across BMI groups, self-efficacy regarding F&V consumption was high and few F&V barriers were reported. The most frequently reported barrier was concern about the cost of F&V (36 %). Of the attitudinal F&V-related factors, only concern about wasting food when serving F&V was associated with weight resilience in adjusted models (0·29; 0·09, 0·94). In a model predicting consuming ≥5 F&V servings/d, driving one's own car to the store was the only attitudinal F&V-related factor associated with consumption (1·50; 1·00, 2·24)., Conclusions: In this population, weight resilience may be encouraged by improving access to affordable and convenient F&V options and providing education on ways to make them palatable to the entire household, rather than by shifting women's F&V perceptions, which are already positive.

Objective: To link the INTERGROWTH-21st gestational weight gain standard with the risks of excess maternal postpartum weight retention, approximated by women's weight change between successive pregnancies., Methods: A population-based retrospective cohort study of 58,534 women delivering successive pregnancies in British Columbia, Canada (2000-2015) was conducted. Pregnancy weight gain (kg) in the index pregnancy was converted into a gestational age-standardized z-score using the INTERGROWTH-21st standard. Excess interpregnancy weight gain was defined as weight increases of 5 kg, 10 kg, or obesity (≥30 kg/m 2 ) at the next pregnancy. Weight gain z-scores and excess interpregnancy weight change were associated using logistic regression., Results: For all definitions of excess interpregnancy weight gain, risks remained low and stable below a weight gain z-score of 0 (50th percentile) but rose sharply with increasing z-scores above zero. Compared with women gaining -1 to 0 SD (16th to 50th percentiles), women gaining > 0 to +1 SD (51st to 84th percentiles) were 55% to 84% more likely to retain excess weight between pregnancies. Risks were three- to sixfold higher in women gaining >+1 SD., Conclusions: A large range of the INTERGROWTH-21st percentiles were associated with increased risks of excess interpregnancy weight gain. The standard may normalize high weight gains of women at increased risk of excess weight retention., (© 2017 The Authors. Obesity published by Wiley Periodicals, Inc. on behalf of The Obesity Society (TOS).)

Purpose: To quantify the relationship between pregnancy weight gain with early and late preterm birth and evaluate whether associations differed between non-Hispanic (NH) black and NH white women., Methods: We analyzed a retrospective cohort of all live births to NH black and NH white women in the United States 2011-2015 (n = 10,714,983). We used weight gain z-scores in multiple logistic regression models stratified by prepregnancy body mass index (BMI) and race to calculate population attributable risk (PAR) percentages for the contribution of high and low pregnancy weight gain to early and late preterm birth., Results: Pregnancy weight gain was related to early and late preterm birth, but associations varied by BMI and race. For early preterm birth, the PAR percentage for high pregnancy weight gain ranged from 8 to 10% in NH black women and from 6 to 8% in NH white women. There was little evidence of racial differences in late preterm birth: PAR percentages ranged from 2 to 7% in NH black women and from 3 to 7% in NH white women., Conclusions: Moderate gestational weight gain is associated with lower rate of preterm birth, with greatest reductions for early preterm birth in NH black women., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: To estimate the extent to which prepregnancy obesity explains the Black-White disparity in stillbirth and infant mortality., Methods: A population-based study of linked Pennsylvania birth-infant death certificates (2003-2011; n = 1,055,359 births) and fetal death certificates (2006-2011; n = 3,102 stillbirths) for all singleton pregnancies in non-Hispanic (NH) White and NH Black women was conducted. Inverse probability weighted regression was used to estimate the role of prepregnancy obesity in explaining the race-infant/fetal death association., Results: Compared with NH White women, NH Black women were more likely to have obesity (≥30 kg/m 2 ) and experienced a higher rate of stillbirth (8.3 vs. 3.6 stillbirths per 1,000 live-born and stillborn infants) and infant death (8.5 vs. 3.0 infant deaths per 1,000 live births). When the contribution of prepregnancy obesity was removed, the difference in risk between NH Blacks and NH Whites decreased from 6.2 (95% CI: 5.6-6.7) to 5.5 (95% CI: 4.9-6.2) excess stillbirths per 1,000 and 5.8 (95% CI: 5.3-6.3) to 5.2 (95% CI: 4.7-5.7) excess infant deaths per 1,000., Conclusions: For every 10,000 live births in Pennsylvania (2003-2011), 6 of the 61 excess infant deaths in NH Black women and 5 of the 44 excess stillbirths (2006-2011) were attributable to prepregnancy obesity., Competing Interests: No conflicts of interest, (© 2016 The Obesity Society.)

The objective of this study was to estimate whether maternal history of childhood maltreatment was associated with pre-pregnancy obesity or excessive gestational weight gain. Pregnant women (n = 472) reported pre-pregnancy weight and height and gestational weight gain and were followed up to 16 years post-partum when they reported maltreatment on the Childhood Trauma Questionnaire (CTQ). CTQ score ranged from no maltreatment (25) to severe maltreatment (125). Prenatal mental health modified the association between CTQ score and maternal weight (P < 0.15), and thus stratified models are presented. After adjusting for race, prenatal tobacco, marijuana and alcohol use, a one standard deviation (1 SD) increase in CTQ score was associated with a 45% increase in the risk of pre-pregnancy obesity among the 141 women with elevated anxiety (≥75th percentile on the State Trait Anxiety Inventory) [relative risk, RR (95% confidence interval, CI): 1.45 (1.12, 1.88)], but was not associated among less anxious (<75th percentile) women [RR (95% CI): 1.10 (0.81, 1.51)]. Risk of excessive gestational weight gain was higher [adjusted RR (95% CI): 1.21 (1.07, 1.37)] with every 1 SD increase in CTQ score for anxious women. No association was observed for less anxious women [adjusted RR (95% CI): 0.89 (0.78, 1.02)]. Prenatal depression similarly modified the association between maltreatment and weight gain. Factors such as psychological status and traumatic experiences in early childhood may contribute to pre-pregnancy obesity and excessive gestational weight gain., (© 2014 John Wiley & Sons Ltd.)

Objective: Assessment of the joint and independent relationships of gestational weight gain and prepregnancy body mass index (BMI) on risk of infant mortality was performed., Methods: This study used Pennsylvania linked birth-infant death records (2003-2011) from infants without anomalies born to mothers with prepregnancy BMI categorized as underweight (n = 58,973), normal weight (n = 610,118), overweight (n = 296,630), grade 1 obesity (n = 147,608), grade 2 obesity (n = 71,740), and grade 3 obesity (n = 47,277). Multivariable logistic regression models stratified by BMI category were used to estimate dose-response associations between z scores of gestational weight gain and infant death after confounder adjustment., Results: Infant mortality risk was lowest among normal-weight women and increased with rising BMI category. For all BMI groups except for grade 3 obesity, there were U-shaped associations between gestational weight gain and risk of infant death. Weight loss and very low weight gain among women with grades 1 and 2 obesity were associated with high risks of infant mortality. However, even when gestational weight gain in women with obesity was optimized, the predicted risk of infant death remained higher than that of normal-weight women., Conclusions: Interventions aimed at substantially reducing preconception weight among women with obesity and avoiding very low or very high gestational weight gain may reduce risk of infant death., (© 2015 The Obesity Society.)

Background: Maternal overweight and obesity affect two-thirds of women of childbearing age and may increase the risk of impaired child cognition., Objective: Our objective was to test the hypothesis that high/low gestational weight gain (GWG) and high/low prepregnancy BMI were associated with offspring intelligence quotient (IQ) and executive function at age 10., Methods: Mother-infant dyads (n = 763) enrolled in a birth cohort study were followed from early pregnancy to 10 y postpartum. IQ was assessed by trained examiners with the use of the Stanford Binet Intelligence Scale-4th edition. Executive function was assessed by the number of perseverative errors on the Wisconsin Card Sorting Test and time to complete Part B on the Trail Making Test. Self-reported total GWG was converted to gestational-age-standardized GWG z score. Multivariable linear regression and negative binomial regression were used to estimate independent and joint effects of GWG and BMI on outcomes while adjusting for covariates., Results: At enrollment, the majority of women in the Maternal Health Practices and Child Development cohort were unmarried and unemployed, and more than one-half reported their race as black. The mean ± SD GWG z score was -0.5 ± 1.8, and 27% of women had a pregravid BMI ≥ 25. The median (IQR) number of perseverative errors was 23 (17, 29), the mean ± SD time on Part B was 103 ± 42.6 s, and 44% of children had a low average IQ (≤ 89). Maternal obesity was associated with 3.2 lower IQ points (95% CI: -5.6, -0.8) and a slower time to complete the executive function scale Part B (adjusted β: 12.7 s; 95% CI: 2.8, 23 s) compared with offspring of normal-weight mothers. Offspring of mothers whose GWG was >+1 SD, compared with -1 to +1 SD, performed 15 s slower on the executive function task (95% CI: 1.8, 28 s). There was no association between GWG z score and offspring composite IQ score (adjusted β: -0.32; 95% CI: -0.72, 0.10). Prepregnancy BMI did not modify these associations., Conclusions: Although GWG may be important for executive function, maternal BMI has a stronger relation than GWG to both offspring intelligence and executive function. Our findings contribute to evidence linking maternal obesity to long-term child outcomes., (© 2015 American Society for Nutrition.)

Background: In high-income countries, maternal obesity is one of the most important modifiable causes of stillbirth, yet the pathways underpinning this association remain unclear., Objective: We estimated the association between maternal prepregnancy body mass index (BMI) and the risk of stillbirth defined by pathophysiologic contributors or causes., Design: Using a case-cohort design, we randomly sampled 1829 singleton deliveries from a cohort of 68,437 eligible deliveries at Magee-Womens Hospital in Pittsburgh, Pennsylvania (2003-2010), and augmented it with all remaining cases of stillbirth for a total of 658 cases. Stillbirths were classified based on probable cause(s) of death (maternal medical conditions, obstetric complications, fetal abnormalities, placental diseases, and infection). A panel of clinical experts reviewed medical records, placental tissue slides and pathology reports, and fetal postmortem reports of all stillbirths. Causes of fetal death were assigned by using the Stillbirth Collaborative Research Network Initial Causes of Fetal Death protocol from the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Proportional hazards models were used to estimate the BMI-stillbirth association after adjustment for confounders., Results: The rate of stillbirth among lean, overweight, obese, and severely obese women was 7.7, 10.6, 13.9, and 17.3 per 1000 live-born and stillborn infants, respectively. Adjusted stillbirth HRs (95% CIs) were 1.4 (1.1, 1.8) for overweight, 1.8 (1.3, 2.4) for obese, and 2.0 (1.5, 2.8) for severely obese women, respectively, compared with lean women; associations strengthened when limited to antepartum stillbirths. Obesity and severe obesity were associated with stillbirth resulting from placental diseases, hypertension, fetal anomalies, and umbilical cord abnormalities. BMI was not related to stillbirth caused by placental abruption, obstetric conditions, or infection., Conclusions: Multiple mechanisms appear to link obesity to stillbirth. Interventions to reduce stillbirth among obese mothers should consider targeting stillbirth due to hypertension and placental diseases-the most common causes of fetal death in this at-risk group., (© 2015 American Society for Nutrition.)

Objective: Reference charts for classifying and monitoring pregnancy weight gain in severely obese women do not exist. The goal was to construct pregnancy weight-gain-for-gestational-age z-score charts for overweight and obese mothers, stratified by severity of obesity., Methods: Serial weight gain measurements were abstracted from 1047, 1202, 1267, and 730 overweight, class I, II, and III obese women, respectively, delivering uncomplicated term pregnancies at Magee-Womens Hospital in Pittsburgh, PA. Multi-level linear regression models were used to express serial weight gain measurements as a function of gestational age., Results: There were a median [interquartile range] of 11 [9-12] and 11 [9-13] serial weight measurements for overweight and obese (class I, II, and III) women, respectively. The rate of weight gain was minimal until 15-20 weeks and then increased in a slow, linear manner until term. The slope of weight gain flattened as pre-pregnancy BMI increased. Charts were created describing the mean, standard deviation, and select percentiles of weight gain in class I, II, and III obese and overweight pregnancies., Conclusions: These charts are an innovative tool for studying the association between gestational weight gain and adverse pregnancy outcomes., (© 2015 The Obesity Society.)

Objective: To estimate the absolute risks of adverse maternal and perinatal outcomes based on small differences in prepregnancy body mass (eg, 10% of body mass or 10-20 pounds)., Methods: This population-based cohort study (N=226,958) was drawn from all singleton pregnancies in British Columbia (Canada) from 2004 to 2012. The relationships between prepregnancy body mass index (BMI) (as a continuous, nonlinear variable) and adverse pregnancy outcomes were examined using logistic regression models. Analyses were adjusted for maternal age, height, parity, and smoking in pregnancy. Adjusted absolute risks of each outcome are reported according to incremental differences in prepregnancy BMI and weight in pounds., Results: A 10% difference in prepregnancy BMI was associated with at least a 10% lower risk of preeclampsia, gestational diabetes, indicated preterm delivery, macrosomia, and stillbirth. In contrast, larger differences in prepregnancy BMI (20-30% differences in BMI) were necessary to meaningfully reduce risks of cesarean delivery, shoulder dystocia, neonatal intensive care unit stay 48 hours or longer, and in-hospital newborn mortality. Prepregnancy BMI was not associated with risk of postpartum hemorrhage requiring intervention, severe maternal morbidity or maternal mortality, or spontaneous preterm delivery before 32 weeks of gestation., Conclusion: These results can inform prepregnancy weight loss counseling by defining achievable weight loss goals for patients that may reduce their risk of poor perinatal outcomes., Level of Evidence: II.

To investigate the relationship among parity, length of the inter-pregnancy intervals and excessive pregnancy weight gain in the first pregnancy and the risk of obesity. Using a prospective cohort study of 3,422 non-obese, non-pregnant US women aged 14-22 years at baseline, adjusted Cox models were used to estimate the association among parity, inter-pregnancy intervals, and excessive pregnancy weight gain in the first pregnancy and the relative hazard rate (HR) of obesity. Compared to nulliparous women, primiparous women with excessive pregnancy weight gain in the first pregnancy had a HR of obesity of 1.79 (95% CI 1.40, 2.29); no significant difference was seen between primiparous without excessive pregnancy weight gain in the first pregnancy and nulliparous women. Among women with the same pregnancy weight gain in the first pregnancy and the same number of inter-pregnancy intervals (12 and 18 months or ≥18 months), the HR of obesity increased 2.43-fold (95% CI 1.21, 4.89; p = 0.01) for every additional inter-pregnancy interval of <12 months; no significant association was seen for longer inter-pregnancy intervals. Among women with the same parity and inter-pregnancy interval pattern, women with excessive pregnancy weight gain in the first pregnancy had an HR of obesity 2.41 times higher (95% CI 1.81, 3.21; p < 0.001) than women without. Primiparous and nulliparous women had similar obesity risk unless the primiparous women had excessive pregnancy weight gain in the first pregnancy, then their risk of obesity was greater. Multiparous women with the same excessive pregnancy weight gain in the first pregnancy and at least one additional short inter-pregnancy interval had a significant risk of obesity after childbirth. Perinatal interventions that prevent excessive pregnancy weight gain in the first pregnancy or lengthen the inter-pregnancy interval are necessary for reducing maternal obesity.

Objective: Pre-pregnancy obesity has been associated with adverse birth outcomes. Poor essential fatty acid (EFA) and micronutrient status during pregnancy may contribute to these associations. We assessed the associations between pre-pregnancy BMI and nutritional patterns of maternal micronutrient and EFA status during mid-pregnancy., Design: A cross-sectional analysis from a prospective cohort study. Women provided non-fasting blood samples at ≥ 20 weeks’ gestation that were assayed for red cell EFA; plasma folate, homocysteine and ascorbic acid; and serum retinol, 25-hydroxyvitamin D, a-tocopherol, soluble transferrin receptors and carotenoids. These nutritional biomarkers were employed in a factor analysis and three patterns were derived: EFA, Micronutrients and Carotenoids., Setting: The Antidepressant Use During Pregnancy Study, Pittsburgh, PA, USA., Subjects: Pregnant women (n 129)., Results: After adjustment for parity, race/ethnicity and age, obese pregnant women were 3.0 (95% CI 1.1, 7.7) times more likely to be in the lowest tertile of the EFA pattern and 4.5 (95% CI 1.7, 12.3) times more likely to be in the lowest tertile of the Carotenoid pattern compared with their lean counterparts. We found no association between pre-pregnancy obesity and the Micronutrient pattern after confounder adjustment., Conclusions: Our results suggest that obese pregnant women have diminished EFA and carotenoid concentrations.

There is growing interest in the relationship between gestational weight gain (GWG) and long-term maternal and child outcomes, yet little is known about the accuracy of long-term maternal recall of GWG. Our objective was to assess the accuracy of maternal recall of GWG at 4-12 years postpartum (mean, 8 years) compared with medical-record documented GWG, and compare recalled GWG to documented GWG with respect to their associations with adverse pregnancy outcomes including small for gestational age (SGA) birth, preterm birth, cesarean delivery, and postpartum weight retention (PPWR) (n = 503). Adequacy of recalled and documented GWG was assessed according to the 2009 Institute of Medicine (IOM) guidelines. We observed moderate agreement between documented and maternal self-reported GWG as continuous variables (r = 0.63, P < 0.01). When recalled GWG was used to categorize women, 45, 53, and 20% of women with inadequate, adequate, and excessive documented GWG were misclassified, respectively. When comparing models fitted with documented or recalled GWG, there were no meaningful differences in associations between inadequate GWG and SGA birth (odds ratio 2.2 (95% confidence interval: 1.3, 3.7) vs. 2.1 (1.2, 3.8), respectively) or excessive GWG and PPWR (2.5 (1.6, 3.9) vs. 2.5 (1.5, 4.0), respectively). However, the use of recalled GWG attenuated associations between inadequate GWG and PPWR (documented: 0.5 (0.3, 0.9) vs. recalled GWG: 1.3 (0.7, 2.3)) and excessive GWG and preterm birth (documented: 2.5 (1.4, 4.5) vs. recalled GWG: 1.5 (0.9, 2.7)). Our data suggest a varying degree of bias when using recalled GWG to study selected adverse outcomes.

The Institute of Medicine and the National Research Council have issued new guidelines for gestational weight gain as well as recommendations for action and research that call for "a radical change in the care provided to women of childbearing age." For the first time, these guidelines consider the outcomes of both mother and child during and after delivery and the trade-offs between them. The recommendations call for women to begin pregnancy at a healthy weight and to gain within the guidelines, a goal not previously achieved. They also call for individualized preconceptional, prenatal, and postpartum care to help women attain a healthy weight, gain within the guidelines, and return to a healthy weight. Scientific evidence was inadequate to provide specific guidelines by obesity class or to support a public health recommendation to reduce the guidelines below 5-9 kg (11-20 lb) for obese women.

Prepregnancy BMI is a widely used marker of maternal nutritional status that relies on maternal self-report of prepregnancy weight and height. Pregravid BMI has been associated with adverse health outcomes for the mother and infant, but the impact of BMI misclassification on measures of effect has not been quantified. The authors applied published probabilistic bias analysis methods to quantify the impact of exposure misclassification bias on well-established associations between self-reported prepregnancy BMI category and five pregnancy outcomes (small for gestational age (SGA) and large for gestational age (LGA) birth, spontaneous preterm birth (sPTB), gestational diabetes mellitus (GDM), and preeclampsia) derived from a hospital-based delivery database in Pittsburgh, PA (2003-2005; n = 18,362). The bias analysis method recreates the data that would have been observed had BMI been correctly classified, assuming given classification parameters. The point estimates derived from the bias analysis account for random error as well as systematic error caused by exposure misclassification bias and additional uncertainty contributed by classification errors. In conventional multivariable logistic regression models, underweight women were at increased risk of SGA and sPTB, and reduced risk of LGA, whereas overweight, obese, and severely obese women had elevated risks of LGA, GDM, and preeclampsia compared with normal-weight women. After applying the probabilistic bias analysis method, adjusted point estimates were attenuated, indicating the conventional estimates were biased away from the null. However, the majority of relations remained readily apparent. This analysis suggests that in this population, associations between self-reported prepregnancy BMI and pregnancy outcomes are slightly overestimated.

Background: The 2009 Institute of Medicine (IOM) Committee to Reevaluate Gestational Weight Gain Guidelines concluded that there were too few data to inform weight-gain guidelines by obesity severity. Therefore, the committee recommended a single range, 5-9 kg at term, for all obese women., Objective: We explored associations between gestational weight gain and small-for-gestational-age (SGA) births, large-for-gestational-age (LGA) births, spontaneous preterm births (sPTBs), and medically indicated preterm births (iPTBs) among obese women who were stratified by severity of obesity., Design: We studied a cohort of singleton, live-born infants without congenital anomalies born to obesity class 1 (prepregnancy body mass index [BMI (in kg/m(2))]: 30-34.9; n = 3254), class 2 (BMI: 35-39.9; n = 1451), and class 3 (BMI: > or =40; n = 845) mothers. We defined the adequacy of gestational weight gain as the ratio of observed weight gain to IOM-recommended gestational weight gain., Results: The prevalence of excessive gestational weight gain declined, and weight loss increased, as obesity became more severe. Generally, weight loss was associated with an elevated risk of SGA, iPTB, and sPTB, and a high weight gain tended to increase the risk of LGA and iPTB. Weight gains associated with probabilities of SGA and LGA of < or =10% and a minimal risk of iPTB and sPTB were as follows: 9.1-13.5 kg (obesity class 1), 5.0-9 kg (obesity class 2), 2.2 to <5.0 kg (obesity class 3 white women), and <2.2 kg (obesity class 3 black women)., Conclusion: These data suggest that the range of gestational weight gain to balance risks of SGA, LGA, sPTB, and iPTB may vary by severity of obesity.

Obesity is a risk factor for vitamin D deficiency, but this relation has not been studied among pregnant women, who must sustain their own vitamin D stores as well as those of their fetuses. Our objective was to assess the effect of prepregnancy BMI on maternal and newborn 25-hydroxyvitamin D [25(OH)D] concentrations. Serum 25(OH)D was measured at 4-21 wk gestation and predelivery in 200 white and 200 black pregnant women and in their neonates' cord blood. We used multivariable logistic regression models to assess the independent association between BMI and the odds of vitamin D deficiency [25(OH)D <50 nmol/L] after adjustment for race/ethnicity, season, gestational age, multivitamin use, physical activity, and maternal age. Compared with lean women (BMI <25), pregravid obese women (BMI >or=30) had lower adjusted mean serum 25(OH)D concentrations at 4-22 wk (56.5 vs. 62.7 nmol/L; P < 0.05) and a higher prevalence vitamin D deficiency (61 vs. 36%; P < 0.01). Vitamin D status of neonates born to obese mothers was poorer than neonates of lean mothers (adjusted mean, 50.1 vs. 56.3 nmol/L; P < 0.05). There was a dose-response trend between prepregnancy BMI and vitamin D deficiency. An increase in BMI from 22 to 34 was associated with 2-fold (95% CI: 1.2, 3.6) and 2.1-fold (1.2, 3.8) increases in the odds of mid-pregnancy and neonatal vitamin D deficiency, respectively. The rise in maternal obesity highlights that maternal and newborn vitamin D deficiency will continue to be a serious public health problem until steps are taken to identify and treat low 25(OH)D.

The objective of this study was to quantify the mediating role of inflammation and triglycerides in the association between prepregnancy body mass index (weight (kg)/height (m)2) and preeclampsia. The authors conducted a nested case-control study of 55 preeclamptic women and 165 pregnant controls from the Pregnancy Exposures and Preeclampsia Prevention Study (Pittsburgh, Pennsylvania, 1997-2001). Serum samples collected at < or = 20 weeks' gestation were analyzed for levels of C-reactive protein and triglycerides. The adjusted odds ratio (AOR) from a multivariable conditional logistic regression model assessing the total effect of body mass index on preeclampsia risk was compared with the AOR from the same model after results were controlled for C-reactive protein, triglycerides, and confounding factors (direct-effects model). The percentage of the total effect that was mediated through inflammation and triglycerides was calculated as 100 - [ln(direct-effects AOR)/ln(total-effects AOR)]. In the total-effects model, 4- and 8-unit increases in body mass index were associated with 1.7-fold (95% confidence interval (CI): 1.3, 2.3) and 2.9-fold (95% CI: 1.6, 5.2) increases in preeclampsia risk, whereas in the direct-effects model, these AORs were 1.4 (95% CI: 1.0, 1.9) and 2.0 (95% CI: 1.0, 3.8), respectively. Inflammation was a more important mediator than triglycerides. These findings suggest that approximately one third of the total effect of body mass index on preeclampsia risk is mediated through inflammation and triglyceride levels.

Purpose: To explore the dose-dependent relation between prepregnancy body mass index (BMI) and the risk of preeclampsia after adjusting for measured confounders., Methods: We studied 1179 primiparous women who enrolled at < 16 weeks' gestation into a prospective cohort study of the pathogenesis of preeclampsia. Multivariable logistic regression was used to quantify the independent effect of prepregnancy BMI on the risk of preeclampsia after adjusting for race and smoking status. BMI was specified as a restricted quadratic spline., Results: Preeclampsia risk rose strikingly from a BMI of 15 to 30 kg/m(2). Compared with women with a BMI of 21, the adjusted risk of preeclampsia doubled at a BMI of 26 (odds ratio 2.1 [95% confidence interval, 1.4, 3.4]), and nearly tripled at a BMI of 30 (2.9 [1.6, 5.3]). Women with a BMI of 17 had a 57% reduction in preeclampsia risk compared with women with a BMI of 21 (0.43 [0.25, 0.76]), and a BMI of 19 was associated with a 33% reduction in risk (0.66 [0.50, 0.87])., Conclusions: These results indicate that preeclampsia risk rises through most of the BMI distribution. The dramatic elevation in overweight prevalence in the United States may increase preeclampsia incidence in the future.

Objective: To assess the independent effect of prepregnancy BMI on the risk of postpartum anemia., Research Methods and Procedures: Pregnant women from North Carolina who enrolled in the Iron Supplementation Study at their first prenatal visit at <20 weeks gestation and who delivered a live infant were followed to the postpartum visit (n = 439). BMI had a curvilinear relation in the logit of postpartum anemia; therefore, a restricted quadratic spline with three knots at the inflection points was used to specify BMI. Multiple log binomial regression was used to quantify the relation between prepregnancy BMI and postpartum anemia after adjusting for maternal ethnicity/race, education, smoking, initial hemoglobin concentration, and prenatal iron supplementation., Results: Prevalence of postpartum anemia was 19.1%. After adjusting for confounders, we found that risk of postpartum anemia was similar for women with BMI values from 17 to 24 compared with women with a BMI of 20. Adjusted relative risk increased as BMI increased from 24 to 38. Women with a BMI of 28 had approximately 1.8 times the postpartum anemia risk of a woman with a BMI of 20 (95% confidence interval 1.3, 2.5), and obese women with a BMI of 36 had approximately 2.8 times the risk (95% confidence interval 1.7, 4.7)., Discussion: These data suggest that high prepregnancy BMI substantially increases the risk of postpartum anemia. Postpartum anemia screening and iron supplementation of overweight and obese women may be warranted.

BackgroundExpert groups recommend that women set a pregnancy weight gain goal with their care provider to optimise weight gain.ObjectiveOur aim was to describe the concordance between first-trimester personal and provider pregnancy weight gain goals with the Institute of Medicine (IOM) recommendations and to determine the association between these goals and total weight gain.MethodsWe used data from 9353 women in the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be. In the first trimester, women reported their personal pregnancy weight gain goal and their provider weight gain goal, and we categorised personal and provider weight gain goals and total weight gain according to IOM recommendations. We used log-binomial or linear regression models to relate goals to total weight gain, adjusting for confounders including race/ethnicity, maternal age, education, smoking, marital status and planned pregnancy.ResultsApproximately 37% of women reported no weight gain goals, while 24% had personal and provider goals, 31% had only a personal goal, and 8% had only a provider goal. Personal and provider goals were outside the recommended ranges in 12%-23% of normal-weight women, 31%-41% of overweight women and 47%-63% of women with obesity. Women with both personal and provider pregnancy weight gain goals were 6%-14% more likely than their counterparts to have a goal within IOM-recommended ranges. Having any goal or a goal within the IOM-recommended ranges was unrelated to pregnancy weight gain. Excessive weight gain occurred in approximately half of normal-weight or obese women and three-quarters of overweight women, regardless of goal setting group.ConclusionsThese findings do not support the effectiveness of early-pregnancy personal or provider gestational weight gain goal setting alone in optimising weight gain. Multifaceted interventions that address a number of mediators of goal setting success may assist women in achieving weight gain consistent with their goals.

There are concerns that current gestational weight gain recommendations for women with obesity are too high and that guidelines should differ on the basis of severity of obesity. In this study we investigated the safety of gestational weight gain below current recommendations or weight loss in pregnancies with obesity, and evaluated whether separate guidelines are needed for different obesity classes. In this population-based cohort study, we used electronic medical records from the Stockholm–Gotland Perinatal Cohort study to identify pregnancies with obesity (early pregnancy BMI before 14 weeks' gestation ≥30 kg/m2) among singleton pregnancies that delivered between Jan 1, 2008, and Dec 31, 2015. The pregnancy records were linked with Swedish national health-care register data up to Dec 31, 2019. Gestational weight gain was calculated as the last measured weight before or at delivery minus early pregnancy weight (at <14 weeks' gestation), and standardised for gestational age into z-scores. We used Poisson regression to assess the association of gestational weight gain z-score with a composite outcome of: stillbirth, infant death, large for gestational age and small for gestational age at birth, preterm birth, unplanned caesarean delivery, gestational diabetes, pre-eclampsia, excess postpartum weight retention, and new-onset longer-term maternal cardiometabolic disease after pregnancy, weighted to account for event severity. We calculated rate ratios (RRs) for our composite adverse outcome along the weight gain z-score continuum, compared with a reference of the current lower limit for gestational weight gain recommended by the US Institute of Medicine (IOM; 5 kg at term). RRs were adjusted for confounding factors (maternal age, height, parity, early pregnancy BMI, early pregnancy smoking status, prepregnancy cardiovascular disease or diabetes, education, cohabitation status, and Nordic country of birth). Our cohort comprised 15 760 pregnancies with obesity, followed up for a median of 7·9 years (IQR 5·8–9·4). 11 667 (74·0%) pregnancies had class 1 obesity, 3160 (20·1%) had class 2 obesity, and 933 (5·9%) had class 3 obesity. Among these pregnancies, 1623 (13·9%), 786 (24·9%), and 310 (33·2%), respectively, had weight gain during pregnancy below the lower limit of the IOM recommendation (5 kg). In pregnancies with class 1 or 2 obesity, gestational weight gain values below the lower limit of the IOM recommendation or weight loss did not increase risk of the adverse composite outcome (eg, at weight gain z-score –2·4, corresponding to 0 kg at 40 weeks: adjusted RR 0·97 [95% CI 0·89–1·06] in obesity class 1 and 0·96 [0·86–1·08] in obesity class 2). In pregnancies with class 3 obesity, weight gain values below the IOM limit or weight loss were associated with reduced risk of the adverse composite outcome (eg, adjusted RR 0·81 [0·71–0·89] at weight gain z-score –2·4, or 0 kg). Our findings support calls to lower or remove the lower limit of current IOM recommendations for pregnant women with obesity, and suggest that separate guidelines for class 3 obesity might be warranted. Karolinska Institutet and the Eunice Kennedy Shriver National Institute of Child Health and Human Development. [ABSTRACT FROM AUTHOR]

Objective: This case‐cohort study estimated associations between gestational weight gain (GWG) and small‐for‐gestational‐age (SGA) and large‐for‐gestational‐age (LGA) births stratified by obesity class (I: 30–34.9 kg/m2; II: 35–39.9 kg/m2; III: ≥40 kg/m2) (Magee‐Womens Hospital, Pittsburgh, Pennsylvania, 1998–2011). Methods: First‐trimester GWG was categorized as being below (<0.2 kg), within (0.2–2.0 kg), or above (>2.0 kg) the Institute of Medicine recommendations. For second‐ and third‐trimester GWG, four linear trajectories were derived: approximating maintenance (slope −0.05 ± 0.03 kg/wk), approximating the recommendations (0.27 ± 0.01 kg/wk; reference), higher than the recommendations (0.54 ± 0.01 kg/wk), and highest among those above the recommendations (0.91 ± 0.02 kg/wk). Results: For classes I, II, and III, respectively, there were 1290, 1247, and 1198 pregnancies in the subcohort; 262, 171, and 123 SGA cases; and 353, 286, and 257 LGA cases. First‐trimester GWG was not associated with SGA/LGA births. Second‐ and third‐trimester weight maintenance was associated with potentially lower LGA risk (risk ratio [RR]: 0.80; 95% confidence interval [CI]: 0.55–1.1) but not higher SGA risk (RR: 0.98; 95% CI: 0.64–1.5) for class III. In addition, some sensitivity analyses supported no increased SGA risk with second‐ and third‐trimester weight maintenance for classes I and II. Conclusions: Second‐ and third‐trimester weight maintenance may be associated with more optimal birth weight for gestational age. However, how this could be achieved (e.g., through diet and exercise interventions) is unclear, given the observational design of our study. [ABSTRACT FROM AUTHOR]

The Dietary Guidelines for Americans rely on summaries of the effect of dietary pattern on disease risk, independent of other population characteristics. We explored the modifying effect of prepregnancy body mass index (BMI; weight (kg)/height (m)2) on the relationship between fruit and vegetable density (cup-equivalents/1,000 kcal) and preeclampsia using data from a pregnancy cohort study conducted at 8 US medical centers (n  = 9,412; 2010–2013). Usual daily periconceptional intake of total fruits and total vegetables was estimated from a food frequency questionnaire. We quantified the effects of diets with a high density of fruits (≥1.2 cups/1,000 kcal/day vs. <1.2 cups/1,000 kcal/day) and vegetables (≥1.3 cups/1,000 kcal/day vs. <1.3 cups/1,000 kcal/day) on preeclampsia risk, conditional on BMI, using a doubly robust estimator implemented in 2 stages. We found that the protective association of higher fruit density declined approximately linearly from a BMI of 20 to a BMI of 32, by 0.25 cases per 100 women per each BMI unit, and then flattened. The protective association of higher vegetable density strengthened in a linear fashion, by 0.3 cases per 100 women for every unit increase in BMI, up to a BMI of 30, where it plateaued. Dietary patterns with a high periconceptional density of fruits and vegetables appear more protective against preeclampsia for women with higher BMI than for leaner women. [ABSTRACT FROM AUTHOR]

Background: Gestational diabetes might be more common in twin versus singleton pregnancies, yet the reasons for this are unclear. We evaluated the extent to which this relationship is explained by higher mid-pregnancy weight gain within normal weight and overweight pre-pregnancy body mass index (BMI) strata.Methods: We analyzed serial weights and glucose screening and diagnostic data abstracted from medical charts for twin (n = 1397) and singleton (n = 3117) pregnancies with normal or overweight pre-pregnancy BMI delivered from 1998 to 2013 at Magee-Womens Hospital in Pennsylvania. We used causal mediation analyses to estimate the total effect of twin versus singleton pregnancy on gestational diabetes, as well as those mediated (natural indirect effect) and not mediated (natural and controlled direct effects) by pathways involving mid-pregnancy weight gain.Results: Odds of gestational diabetes were higher among twin pregnancies [odds ratios (ORs) for total effect = 2.83 (95% CI = 1.54, 5.19) for normal weight and 2.09 (95% CI = 1.16, 3.75) for overweight pre pregnancy BMI], yet there was limited evidence that this relationship was mediated by mid-pregnancy weight gain [ORs for natural indirect effect = 1.21 (95% CI = 0.90, 1.24) for normal weight and 1.06 (95% CI = 0.92, 1.21) for overweight pre-pregnancy BMI] and more evidence of mediation via other pathways [ORs for natural direct effect = 2.34 (95% CI = 1.24, 4.40) for normal weight and 1.97 (95% CI = 1.08, 3.60) for overweight pre-pregnancy BMI].Conclusions: While twin pregnancies with normal weight or overweight pre-pregnancy BMI experienced higher odds of gestational diabetes versus singletons, most of this effect was explained by pathways not involving mid-pregnancy weight gain. [ABSTRACT FROM AUTHOR]

Background: Despite a call to study the effect of weight gain pattern on development of gestational diabetes mellitus, few studies have correctly adjusted for independent effects of gain after the first trimester. We used a conditional percentile approach to model the independent association between first and second trimester weight gain trajectories and development of gestational diabetes.Methods: We sampled women delivering singleton infants from 1998 to 2010 at Magee-Womens Hospital in Pittsburgh, PA, (n = 124,590) using a case-cohort design. We modeled weight gain trajectories in the first and second trimesters of pregnancy using conditional weight gain percentiles, and used multivariable logistic regression to assess independent associations of the trajectory with gestational diabetes. We studied associations separately by prepregnancy body mass index category.Results: The final cohort included 806 women with gestational diabetes and 4,819 randomly sampled women who delivered without gestational diabetes. In normal-weight women, every SD increase in weight gain in the first trimester above her predicted gain was associated with a 23% increased odds of gestational diabetes (95% confidence interval: 0.2%, 51%). Second trimester gain trajectory was not associated with gestational diabetes (odds ratio: 1.1, [95% confidence interval: 0.9, 1.3]) although the direction of effect was positive. This pattern was similar in obese class I and II but not in overweight and obese class III women.Conclusions: An upward weight gain trajectory in the first trimester was positively associated with gestational diabetes for women of most prepregnancy BMI categories. Second trimester weight gain trajectory was not associated with gestational diabetes for any group. [ABSTRACT FROM AUTHOR]

Background: Gestational weight gain is often characterized by the total amount of weight gained during pregnancy, however, the pattern of gain may be an important determinant of health outcomes. The SITAR (Super Imposition by Translation And Rotation) model has been used to describe childhood growth trajectories and has appeal because of the biological interpretability of its parameters. The objective of this study was to determine the feasibility of applying this model to gestational weight gain trajectories.Methods: The study cohort included 3470 normal-weight, overweight, and obese women delivering at Magee-Womens Hospital in Pittsburgh, Pennsylvania, 1998 to 2010. We applied the SITAR model, a non-linear mixed effects model, to serial prenatal weight gain measurements in each pre-pregnancy body mass index (BMI) category. We fit models of varying complexity, and chose the best-fitting model to describe the pattern of weight gain (by its absolute amount, timing, and acceleration) for each BMI group.Results: The most complex SITAR models failed to converge, but reduced models could successfully be fit by specifying fewer random effects and simplifying the modelling of gestational age. Best-fitting models for each BMI group explained between 95% and 97% of the variation in weight gain trajectories. Peak rates of weight gain were reached between the 20th and 22nd weeks, and were higher for normal and overweight women (0.59 kg/week and 0.57 kg/week, respectively) than obese women (0.46 kg/week).Conclusions: Following some modifications, the SITAR model can be used to characterize pregnancy weight gain patterns. [ABSTRACT FROM AUTHOR]

Birth certificates are an important source of pre‐pregnancy body mass index (BMI) and gestational weight gain (GWG) data for surveillance and aetiologic studies, but little is known about their validity in twin pregnancies. Twins experience high rates of adverse perinatal outcomes that have been associated with BMI and GWG in singletons. Our objective was to evaluate the accuracy of birth certificate‐derived pre‐pregnancy BMI and GWG compared with medical record‐derived data in a sample of 186 twin pregnancies at a teaching hospital in Pennsylvania (2003–2010). Twelve strata were created by simultaneous stratification on pre‐pregnancy BMI (underweight, normal weight/overweight, obese class 1, obese classes 2 and 3) and GWG (<20th, 20–80th, >80th percentile). The agreement of birth certificate‐derived pre‐pregnancy BMI category with medical record BMI category was lowest among underweight mothers [75% (95% confidence interval 51–91%) ] and highest among normal/overweight [97% (90–99%) ] and obese classes 2 and 3 mothers [97% (85–99%) ]. Agreement for GWG category from the birth certificate varied from 57% (41–70%) for GWG >80th percentile to 80% (65–91%) and 82% (72–89%) for GWG <20th and 20th–80th percentiles, respectively. The misclassification of BMI and GWG was primarily due to error in pre‐pregnancy weight rather than weight at delivery or height. Agreement proportions for twins were not meaningfully different from the proportions in a comparable sample of singleton pregnancies. These data suggest that birth certificate‐based BMI and GWG data are prone to error in twin pregnancies. Those who use these data should conduct internal validation studies and adjust their results using bias analyses. [ABSTRACT FROM AUTHOR]

Background: Current approaches for establishing public health guidelines on the recommended range of weight gain in pregnancy are subjective and nonsystematic. Objective: In this article, we outline how decision-making on gestational weight-gain guidelines could be aided by quantitative approaches used in noninferiority trials. Design: We reviewed the theoretical application of noninferiority margins to pregnancy weight-gain guidelines. A worked example illustrated the selection of the recommended range of pregnancy weight gain in women who delivered at the Magee-Womens Hospital, Pittsburgh, PA, in 2003-2010 by identifying weight-gain z scores in which risk of unplanned cesarean delivery, preterm birth, small-for-gestational-age infant, and large-for-gestational-age infant were not meaningfully increased (based on noninferiority margins of 10% and 20%). Results: In normal-weight women, lowest risk of adverse perinatal outcome was observed at a weight-gain z score of -0.2 SDs. With a noninferiority margin of 20%, risks of adverse outcome were not meaningfully increased from the -0.2-SD reference value between z scores of -0.97 and +0.33 SDs (which corresponded to 11.3-18.4 kg). In overweight women, the recommended range was much broader: -2.11 to +0.29 SDs (4.4-18.1 kg). Conclusion: The new approach illustrated in this article has a number of advantages over current methods for establishing pregnancy weight-gain guidelines because it is systematic, it is reproducible, and it provides a tool for policy makers to derive guidelines that explicitly reflect values at which risk of adverse outcome becomes meaningfully increased. [ABSTRACT FROM AUTHOR]

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Abstract: The incidence of obesity is increasing at an alarming rate. There is compelling evidence that obesity increases the risk of preeclampsia about three-fold, and in developed countries is the leading attributable risk for the disorder. In this presentation we explore this relationship and propose targets for future studies guided by the much more extensively studied relationship of obesity to cardiovascular disease. We further address the hypothesis that asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, may be one convergence point for the mechanism by which obesity increases the risk of preeclampsia. We conclude with consideration of the clinical implications of this information. [Copyright &y& Elsevier]

Objective: To assess seasonal variability in antenatal blood pressure (BP).Methods: We studied 1919 pregnant women who contributed 21,119 antenatal BP measurements.Results: BP peaked in winter and reached a nadir in summer. After confounder adjustment, systolic BP was 1.0 to 1.7 mm Hg higher January to May, 0.6 mm Hg higher in September and October, and 0.8 mm Hg higher in November and December compared with August. After stratifying by overweight status, BP showed strong seasonal variability among lean women, whereas there were no seasonal trends among overweight women.Conclusion: Environmental factors may regulate gestational BP and may be relevant to seasonality of hypertensive disorders of pregnancy. [ABSTRACT FROM AUTHOR]

The objective was to assess the independent effect of regular periconceptional multivitamin use on the risk of preeclampsia. Pregnant women (n = 1,835) enrolled in the Pregnancy Exposures and Preeclampsia Prevention Study (Pittsburgh, Pennsylvania, 1997–2001) at less than 16 weeks' gestation were asked whether they regularly used multivitamins or prenatal vitamins in the past 6 months. Women were classified as users or nonusers. The unadjusted prevalence of preeclampsia was 4.4% in nonusers and 3.8% in users. After adjustment for race/ethnicity, marital status, parity, prepregnancy physical activity, and income in a multiple logistic regression model, regular use of multivitamins was associated with a 45% reduction in preeclampsia risk compared with nonuse (odds ratio (OR) = 0.55, 95% confidence interval (CI): 0.32, 0.95). Prepregnancy overweight modified this effect. After confounder adjustment, lean multivitamin users had a 71% reduction in preeclampsia risk compared with lean nonusers (OR = 0.29, 95% CI: 0.12, 0.65). In contrast, there was no relation between multivitamin use and preeclampsia among overweight women (OR = 1.08, 95% CI: 0.52, 2.25). A sensitivity analysis for unmeasured confounding by fruit and vegetable intake supported these conclusions. If confirmed by others, these results suggest that regular use of a multivitamin supplement in the periconceptional period may help to prevent preeclampsia, particularly among lean women. [ABSTRACT FROM AUTHOR]