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The purpose of this study was to examine the association between prenatal alcohol consumption and the occurrence of placental abruption and placenta previa in a population-based sample. We used linked birth data files to conduct a retrospective cohort study of singleton deliveries in the state of Missouri during the period 1989 through 2005 (n = 1,221,310). The main outcomes of interest were placenta previa, placental abruption and a composite outcome defined as the occurrence of either or both lesions. Multivariate logistic regression was used to generate adjusted odd ratios, with non-drinking mothers as the referent category. Women who consumed alcohol during pregnancy had a 33% greater likelihood for placental abruption during pregnancy (adjusted odds ratio (OR), 95% confidence interval (CI) = 1.33 [1.16-1.54]). No association was observed between prenatal alcohol use and the risk of placenta previa. Alcohol consumption in pregnancy was positively related to the occurrence of either or both placental conditions (adjusted OR [95% CI] = 1.29 [1.14-1.45]). Mothers who consumed alcohol during pregnancy were at elevated risk of experiencing placental abruption, but not placenta previa. Our findings underscore the need for screening and behavioral counseling interventions to combat alcohol use by pregnant women and women of childbearing age.

Objective: To determine if cesarean delivery is associated with improved survival and morbidity in the breech fetus at the threshold of viability., Study Design: The Missouri maternally linked cohort data files covering the period 1989 through 2005 were utilized for analysis. All pregnancies with singleton fetuses in the breech presentation delivered between 23(0) and 24(6) weeks gestation and birth weights between 400 and 750 g were included. Logistic regression was used to compare cesarean to vaginal delivery after controlling for maternal demographics and pregnancy complications., Results: A total of 325 breech singletons were analyzed; cesarean deliveries accounted for 46.1% (150) and vaginal deliveries accounted for 53.9% (175). Cesarean delivery was associated with a survival benefit across all birth weights. Morbidity was higher in cesarean compared to vaginal delivery., Conclusion: Although cesarean delivery appears to be associated with an increase in survival at the threshold of viability for the breech fetus, there is a concomitant increase in morbidity. Any benefit that cesarean delivery conveys on survival at the threshold of viability should be weighed against the increased maternal morbidity and high overall neonatal morbidity.

Introduction: Cigarette smoking is an established risk factor for adverse perinatal outcomes. The purpose of this study is to examine the association between maternal smoking in pregnancy and the occurrence of placental-associated syndromes (PAS)., Methods: We analyzed data from a population-based retrospective cohort of singleton deliveries that occurred in the state of Missouri from 1989 through 2005 (N = 1,224,133). The main outcome was PAS, a composite outcome defined as the occurrence of placental abruption, placenta previa, preeclampsia, small for gestational age, preterm or stillbirth. We used logistic regression models to generate adjusted odd ratios and their 95 percent confidence intervals. Non-smoking gravidas served as the referent category., Results: The overall prevalence of prenatal smoking was 19.6%. Cigarette smoking in pregnancy was associated with the composite outcome of placental syndromes (odds ratio, 95% confidence interval = 1.59, 1.57-1.60). This association showed a dose-response relationship, with the risk of PAS increasing with increased quantity of cigarettes smoked. Similar results were observed between smoking in pregnancy and independent risks for abruption, previa, SGA, stillbirth, and preterm delivery., Conclusion: Maternal smoking in pregnancy is a risk factor for the development of placenta-associated syndrome. Smoking cessation interventions in pregnancy should continue to be encouraged in all maternity care settings.

Background: The aetiology of preterm birth remains poorly understood. The purpose of this study is to investigate if an association exists between prenatal alcohol consumption and preterm birth and to determine if such an association differs by subcategories of preterm birth., Methods: We employed vital statistics data from the state of Missouri covering the period 1989-2005 (n = 1 221 677 singleton records). The outcome of interest was preterm birth, subclassified into medically indicated and spontaneous phenotypes. Multivariate logistic regression was used to generate adjusted odds ratios, with non-drinking mothers as the referent category., Results: Prenatal alcohol use was associated with elevated risk for preterm birth. The strength of association was more prominent for spontaneous preterm delivery {adjusted odds ratio (AOR) [95% confidence interval (CI)] = 1.34 (1.28-1.41)} than for medically indicated preterm birth [AOR (95% CI) = 1.16 (1.05-1.28)]. The overall risk for drinking-related spontaneous preterm birth increased with incremental rise in the number of drinks consumed per week (P for trend < 0.01)., Conclusions: Prenatal alcohol use is a risk factor for preterm delivery, and especially for spontaneous preterm birth. These findings enhance our understanding of the aetiology of preterm birth and could be utilized in the development of appropriate prevention strategies that will assist in decreasing perinatal mortality and morbidity associated with preterm delivery.

We investigated the association between prenatal smoking and the occurrence of medically indicated and spontaneous preterm delivery (<37 weeks). We performed a retrospective cohort study of singleton live births in the state of Missouri (n = 1,219,159) using maternally linked cohort data files covering the period 1989 to 2005. The main outcomes of interest were spontaneous and medically indicated preterm and very preterm birth. Logistic regression models were used to generate adjusted odds ratios and their 95% confidence intervals. There were 132,246 (10.8%) infants born preterm in the study population, of which 106,410 (80.5%) were classifiable as spontaneous preterm births and 25,836 (19.5%) were medically indicated preterm deliveries. We found elevated risks for both medically indicated and spontaneous preterm birth associated with maternal cigarette smoking during pregnancy. This heightened risk was particularly evident for medically indicated preterm birth (adjusted odds ratio [95% confidence interval] = 1.48 [1.41 to 1.55]). Women who smoke during pregnancy are at increased risk for preterm birth, and especially for medically indicated preterm delivery., (Copyright Thieme Medical Publishers.)

We sought to determine if there is a relationship between prepregnancy underweight status and placental abruption. We utilized the Missouri maternally linked cohort data files covering the period 1989 through 1997. We estimated the association between prepregnancy underweight subtypes and placental abruption using adjusted odds ratios. Subanalyses were performed to determine whether the amount of weight gained during pregnancy could modify the association. A total of 439,235 singleton pregnancies with 3696 abruptions were analyzed. Underweight mothers had a 40% greater likelihood for placental abruption (odds ratio 1.4; 95% confidence interval 1.3 to 1.5). The risk increased with ascending severity of underweight status ( P for trend <0.01). There was a trend toward decreased risk for placental abruption among underweight women with adequate weight gain in pregnancy. Prepregnancy maternal underweight status is associated with placental abruption. This risk may be reduced with adequate weight gain during pregnancy., (Thieme Medical Publishers.)

Objectives: Placental abruption is a major cause of fetal and neonatal death and has been reported more frequently in twin pregnancies than among singleton gestations. The purpose of this article is to investigate the role of maternal pre-gravid body mass index (BMI) on the risk for placental abruption among twin pregnancies., Methods: We used the Missouri maternally linked cohort files (years 1989-1997) consisting of twin live births (gestational age 20-44 weeks). Maternal pre-gravid weight was classified based on the following BMI-based categories: normal (18.5-24.9), underweight (<18.5), overweight (25-29.9), and obese (>30). We used logistic regression for generated adjusted odds ratios with correction for the presence of intra-cluster correlation using generalized estimating equations., Results: Overall, 261 cases of placental abruption were registered over the entire study period, yielding a placental abruption rate of 14.9/1000. The frequency of placental abruption correlated negatively with maternal BMI in a dose-effect pattern: underweight (19.3/1000); normal weight (16.1/1000); overweight (13.9/1000); and obese (9.5/1000) mothers (p for trend < 0.01). After adjusting for confounders, the likelihood of placental abruption was still lower in obese women (OR = 0.58; 95% CI = 0.38-0.87). By contrast, women who were underweight had a 20-30% greater likelihood for placental abruption when compared with normal weight mothers, although these findings were statistically not significant., Conclusions: There is an inverse relationship between pre-gravid maternal BMI and placental abruption. The mechanism by which obesity impacts the likelihood of placental abruption in twin pregnancies requires further study.

Objective: The association between underweight and stillbirth remains poorly defined, especially across racial/ethnic sub-populations. We investigate the association of pre-pregnancy underweight on the risk for early and late stillbirth among black and white mothers., Methods: We conducted analysis on the Missouri maternally linked data files covering the period 1989-1997 inclusive. Using body mass index (BMI), we categorized mothers as underweight (BMI <18.5) and normal weight (BMI = 18.5-24.9). By applying logistic regression modeling with adjustment for intracluster correlation, we estimated the risk for total, early (-28 weeks of gestation), and late stillbirth (>28 weeks of gestation) among black and white mothers., Results: A total of 1808 cases of stillbirth were registered. The rate of stillbirth among white mothers was 3.7 per 1000, while the rate among blacks was 7.1 per 1000. Underweight black mothers had comparable risk for total (OR, 0.9; 95% CI, 0.7-1.2), early (OR, 1.1; 95% CI, 0.8-1.5), and late stillbirth (OR, 0.8; 95% CI, 0.5-1.2) as compared to their normal-weight counterparts. By contrast, underweight white gravidas had a 30% reduced likelihood (OR, 0.7; 95% CI, 0.6-0.9) for late stillbirth as compared to normal-weight white mothers. However, the risks for total and early stillbirth among underweight white mothers were similar to those of normal-weight white mothers., Conclusion: Low prepregnancy BMI has similar effects on fetal survival in both blacks and whites except for late stillbirth. The underweight white survival advantage over blacks in late pregnancy could probably be due to greater access for identified white at-risk groups to effective obstetrical interventions as previously reported.

Objective(s): There were three primary objectives of this study: (1) to estimate the risk of preterm and very preterm birth by severity of low pre-pregnancy body mass index (BMI), (2) to determine if the risk in preterm and very preterm birth by severity of low pre-pregnancy BMI differs for spontaneous versus medically indicated preterm delivery, and finally (3) to determine if there is a difference in the risk for preterm and very preterm birth by severity of low pre-pregnancy BMI across gradations of gestational weight gain., Study Design: This study utilized the Missouri maternally linked cohort files from 1989 to 1997. After restricting analyses to singleton live births (gestational age 20-44 weeks) and women with either a low or normal BMI, the final study population consisted of 437,403 births. Pre-pregnancy BMI was categorized as normal (19.5-24.9), mild thinness (17.0-18.5), moderate thinness (16.0-16.9) and severe thinness (< or =15.9). Statistical analyses included chi-square tests and logistic regression with generalized estimating equations (GEE)., Results: Underweight mothers were more likely to experience a preterm delivery. For all preterm births, the risk among underweight mothers increased with ascending underweight severity (p<0.01). Higher risk estimates were observed for spontaneous than for medically indicated preterm birth. For each BMI category, extreme risk values for spontaneous preterm births were observed among women with very low gestational weight gain (<0.12 kg/week). Severely thin mothers with very low and very high pregnancy weight gain were at the greatest risk for spontaneous preterm birth. By contrast, underweight women with moderate gestational weight gain (0.23-0.68 kg/week) had the lowest risk for spontaneous preterm birth with the sole exception of moderately underweight gravidas., Conclusions: These findings suggest that women with low or normal pre-pregnancy BMI should be counseled to maintain a moderate level of gestational weight gain (0.23-0.68 kg/week) in order to reduce their risk for preterm birth. Further, our observation that severity of low pre-pregnancy BMI was associated directly (in a dose-response pattern) with preterm birth highlights the importance of preconceptional counseling for women-specifically the importance of women achieving or maintaining a normal weight status prior to pregnancy.

Using data from the Missouri maternally linked files (1989-1997), the authors examined the association among maternal obesity, obesity subtypes, and spontaneous and medically indicated preterm (<37 weeks) and very preterm (<33 weeks) births in singletons and twins. Adjusted odds ratios were obtained with correction for intracluster correlation. The prevalence of obesity increased by 77% over the study period (p(trend) < 0.001). Obese mothers had a lower risk for spontaneous preterm birth, and this was more pronounced among twins (odds ratio = 0.68, 95% confidence interval: 0.62, 0.75) than singletons (odds ratio = 0.84, 95% confidence interval: 0.82, 0.87). However, this association was present only among obese women who gained less than 0.69 kg/week for singletons and between 0.23 and 0.69 kg/week for twins. By contrast, obese mothers with singleton gestation had about 50% greater odds of medically indicated preterm (odds ratio = 1.46, 95% confidence interval: 1.39, 1.54) and very preterm (odds ratio = 1.49, 95% confidence interval: 1.34, 1.65) births, and the risk increases with ascending severity of obesity (p(trend) < 0.01). For extreme obesity, the risk of medically indicated preterm and very preterm births was almost double that for nonobese women. Similar findings were observed in twins. These data suggest that obesity increases the risk for medically indicated but not spontaneous preterm birth in both singletons and twins.