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Abstract: Objective: To determine the effect of smoking on maternal and fetal thyroid function. Study design: This prospective cohort study involved healthy women undergoing elective cesarean section for term singleton infants. Maternal and fetal thyroid indices were compared between smokers (n =21) and non-smokers (n =83). Results: Maternal thyrotropin (TSH) concentrations were significantly lower in smokers than non-smokers (1.75mIU/L versus 2.15mIU/L, respectively, p =0.007), with similar free thyroxine (FT4) concentrations (9.59pmol/L versus 9.56pmol/L, p =0.755). For women who smoked, the correlation between the average number of cigarettes smoked per day and maternal TSH concentrations was −0.427, p =0.054. Infants of smokers and non-smokers had similar umbilical TSH (5.43mIU/L versus 5.82mIU/L, p =0.124) and FT4 concentrations (13.06pmol/L versus 13.57pmol/L, p =0.049). Conclusion: We demonstrated for the first time that women who smoke during pregnancy have significantly lower TSH concentrations than non-smokers. [Copyright &y& Elsevier]

Abstract: Objective: Labetalol and methyldopa are the two antihypertensive drugs most frequently used to control blood pressure for hypertensive disorders of pregnancy. The objective of this study was to assess if labetalol is associated with poor infant outcomes. Study design: Retrospective population-based cohort study using the linked maternal/infant databases in the Province of Saskatchewan. Women with a diagnosis of a hypertensive disorder of pregnancy who delivered a singleton in Saskatchewan from January 1, 1990 to December 31, 2005 and who were dispensed only labetalol or only methyldopa were included in the study. Occurrences of small for gestational age (SGA)<10th percentile, SGA<3rd percentile, preterm birth, stillbirth, hospitalization for respiratory distress syndrome (RDS), sepsis, and seizure during infancy, and infant death were compared. Multiple logistic regression analysis was performed to adjust for potential confounding. Results: A total of 1223 eligible women were included in the final analysis. Among them, 300 received labetalol only and 923 received methyldopa only during pregnancy. For women with chronic hypertension, the rate of hospitalization for RDS, sepsis, and seizure during infancy was significantly higher for infants born to mothers who were dispensed labetalol only as compared with infants born to mothers who were dispensed methyldopa only (adjusted odds ratio (OR) 1.51, 95% confidence interval (CI) 1.02–2.22). Conclusion: Compared with methyldopa, the use of labetalol for chronic hypertension of pregnancy may be associated with increased rate of hospitalization during infancy. [Copyright &y& Elsevier]

Abstract: Objective: To describe trends in and patterns of antihypertensive drug use in a general obstetric population. Study design: Historical cohort study. A total of 18,117 women who gave birth in a Saskatchewan hospital between January 1, 1980 and December 31, 2005 with a diagnosis of hypertensive disorders in pregnancy were identified and included in the analysis. Results: The rate of treatment with antihypertensive drugs for pregnant women with chronic hypertension rose from 19.94% in 1980–1984 to 37.63% in 2000–2005. There were similar increases in antihypertensive drug use from 1.51% to 14.47% for gestational hypertension/non-severe preeclampsia, and from 1.56% to 20.86% for severe preeclampsia/eclampsia. Methyldopa was the most frequently used drug, followed by beta-blockers, with other antihypertensive drugs accounting for about 18.43% of total uses. The use of both methyldopa and labetalol has increased in recent years while the use of other antihypertensive drugs has decreased. Other antihypertensive drugs were more commonly prescribed in earlier gestation, while methyldopa and labetalol were generally prescribed in later gestation. Conclusion: The use of antihypertensive drugs in pregnancy is relatively common and is increasing, with the liberal use of methyldopa and (especially) labetalol contributing appreciably to this increase. [Copyright &y& Elsevier]

Abstract: Objective: To examine impact of cesarean delivery in first pregnancy on neonatal mortality and morbidity in second pregnancy. Study design: Retrospective cohort study using 1995–2002 US birth registration data. Neonatal mortality and morbidity in second pregnancy of cesarean deliveries in the first pregnancy were compared with vaginal deliveries in the first pregnancy. Results: A total of 9,643,175 singleton second births were eligible in the analysis after excluding those with unknown delivery method (1,801,339 with a previous cesarean delivery and 7,841,836 with a previous vaginal delivery). Compared with vaginal delivery group, infants born to mothers with a previous cesarean delivery had increased risks of assisted ventilation (OR=1.47, 95% CI 1.46, 1.49), low Apgar''s score (OR=1.14, 95% CI 1.12, 1.17), seizure (OR=1.36, 95% CI 1.27, 1.45), fetal distress (OR=1.46, 95% CI 1.44, 1.47), and asphyxia-related neonatal death (OR=1.40, 95% CI 1.29, 1.52). The association between mode of delivery in first pregnancy and neonatal outcomes in second pregnancy remained the same after excluding women with chronic health problems or adverse birth history and adjusting for potential confounding factors. Conclusion(s): Cesarean delivery in first pregnancy is associated with increased risks of neonatal morbidity and mortality in second pregnancy. [Copyright &y& Elsevier]

Abstract: Objective: To assess the association between in vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI) and adverse birth outcomes. Study design: Retrospective cohort study involved IVF/ICSI patients who were treated in the Ottawa Fertility Centre from 1996 to 2005 with a viable pregnancy (>20 weeks of gestation) and mothers who conceived naturally. Results: Eleven of the 1044 infants conceived with IVF/ICSI (1.1%) and 7 of the 1910 naturally conceived infants (0.4%) had congenital heart defects (P <0.01). Five of the 138 infants (3.6%) born to mothers with a body mass index>30 and conceived by IVF/ICSI had congenital heart defects, compared with none in the 240 infants born to mothers with a body mass index>30 and conceived naturally (P <0.01). Conclusion: Infants conceived with use of IVF/ICSI have three times as high a risk of a congenital heart defect as naturally conceived infants. [Copyright &y& Elsevier]

Objective: To examine the possible association between oral contraceptive use and adverse birth outcomes.Study Design: We conducted a population-based cohort study of pregnant women who used oral contraceptives within 3 months before their last menstrual period. Subjects were divided into three groups, according to the interval (0-30, 31-60, and 61-90 days) between the dispensing date and their last menstrual period. For each exposed subject, 4 subjects without exposure to oral contraceptives were individually matched by infant's year of birth and plurality and by mother's age and parity.Results: Oral contraceptive use within 30 days prior to the last menstrual period was associated with increased risks of very low birth weight (OR: 3.24, 95% CI: 1.18, 8.92), low birth weight (OR: 1.93, 95% CI: 1.17, 3.20), and preterm birth (OR: 1.61, 95% CI: 1.01, 2.55); however, oral contraceptive use 31-90 days prior to the last menstrual period did not increase the risk of low birth weight or preterm birth.Conclusion: Our results indicate the use of oral contraceptives near the time of conception may be associated with an increased risk of low birth weight and preterm birth. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To create prediction models of early preterm birth for singletons, twin, and triplet pregnancies. Study design: We used a historical cohort study with the 1996 birth registration data for singletons and the 1995–1997 linked birth/infant death dataset for multiple births of the United States. Preterm birth was defined as gestational age <32 completed weeks. Eligible study subjects were randomly allocated to two groups: one group (80% subjects) for the creation of the prediction models, and the other group (20% subjects) for the validation of the established prediction models. Multivariate logistic regressions were used to establish the prediction models. We further assessed the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the established prediction models with different cut-off values in the validation group. Results: The sensitivity, specificity, PPV, and NPV of the established model were 24.58, 93.54, 5.91, and 98.69%, respectively for singletons, 64.66, 57.04, 16.29, and 92.59%, respectively for twins, and 63.57, 53.58, 42.96, and 72.78%, respectively for triplets. Conclusion: The prediction models of early preterm birth for singleton, twin, and triplet pregnancies created by this study could be useful for obstetricians to identify women being at high risk of preterm birth at early gestation. [Copyright &y& Elsevier]

Abstract: Objective:: To determine an appropriate cutoff value to differentiate physiologic and pathologic birth weight discordance, to determine the prevalence of birth weight discordance ≥25% among twin pregnancies in different sub-populations, and to examine its clinical significance. Study design:: Historical cohort study of 147,262 twin sets registered in the United States between 1995 and 1997. Results:: The prevalence of birth weight discordance ≥25% among twin pregnancies was 8.6%. The prevalence of birth weight discordance ≥25% was significantly decreased with increasing total twin birth weight deciles, was more frequently found in twins with discordant gender (9.1%) than in those twins with concordant gender (8.3%) and in mothers whose age was 30 years or older (9.1%) than those of younger mothers (8.1%). Birth weight discordance ≥25% was associated with earlier gestational age at delivery (35.0 weeks versus 36.0 weeks) and higher neonatal mortality (5.4% versus 2.3%) as compared to twins with lower birth weight discordance. Conclusions:: The prevalence of birth weight discordance ≥25% among twin pregnancies was 8.6%, which is associated with lower gestational age at delivery and higher neonatal mortality rates, and may represent a pathologic process. [Copyright &y& Elsevier]