Common strategies to decide whether a variable is a confounder that should be adjusted for in the analysis rely mostly on statistical criteria. The authors present findings from the Slone Epidemiology Unit Birth Defects Study, 1992-1997, a case-control study on folic acid supplementation and risk of neural tube defects. When statistical strategies for confounding evaluation are used, the adjusted odds ratio is 0.80 (95% confidence interval: 0.62, 1.21). However, the consideration of a priori causal knowledge suggests that the crude odds ratio of 0.65 (95% confidence interval: 0.46, 0.94) should be used because the adjusted odds ratio is invalid. Causal diagrams are used to encode qualitative a priori subject matter knowledge.

Objective To provide information on overall medication use throughout pregnancy, with particular focus on the first trimester and specific prescription medications. Study Design The Slone Epidemiology Center Birth Defects Study (BDS), 1976 to 2008, and the National Birth Defects Prevention Study (NBDPS), 1997 to 2003, which together interviewed over 30,000 women about their antenatal medication use. Results Over the last three decades, first trimester use of prescription medication increased by over 60%, and use of four or more medications more than tripled. By 2008, approximately 50% of women reported taking at least 1 medication. Use of some specific medications markedly decreased or increased. Prescription medication use increased with maternal age and education, was highest for non-Hispanic whites, and varied by state. Conclusion These data reflect the widespread and growing use of medications by pregnant women and reinforce the need to study their respective fetal risks and safety.

These data support an association between the maternal use of SSRIs in late pregnancy and PPHN in the offspring; further study of this association is warranted. These findings should be taken into account in decisions as to whether to continue the use of SSRIs during pregnancy.

Folic acid antagonists, which include such common drugs as trimethoprim, triamterene, carbamazepine, phenytoin, phenobarbital, and primidone, may increase the risk not only of neural-tube defects, but also of cardiovascular defects, oral clefts, and urinary tract defects. The folic acid component of multivitamins may reduce the risks of these defects.

Our findings do not show that there are significantly increased risks of craniosynostosis, omphalocele, or heart defects associated with SSRI use overall. They suggest that individual SSRIs may confer increased risks for some specific defects, but it should be recognized that the specific defects implicated are rare and the absolute risks are small.

No abstract

Gastroschisis and small intestinal atresia (SIA) are birth defects that are thought to arise from vascular disruption of fetal mesenteric vessels. Previous studies of gastroschisis have suggested that risk is increased for maternal use of vasoactive over-the-counter medications, including specific analgesics and decongestants. This retrospective study evaluated the relation between maternal use of cough/cold/analgesic medications and risks of gastroschisis and SIA. From 1995 to 1999, the mothers of 206 gastroschisis cases, 126 SIA cases, and 798 controls in the United States and Canada were interviewed about medication use and illnesses. Risks of gastroschisis were elevated for use of aspirin (odds ratio = 2.7, 95% confidence interval: 1.2, 5.9), pseudoephedrine (odds ratio = 1.8, 95% confidence interval: 1.0, 3.2), acetaminophen (odds ratio = 1.5, 95% confidence interval: 1.1, 2.2), and pseudoephedrine combined with acetaminophen (odds ratio = 4.2, 95% confidence interval: 1.9, 9.2). Risks of SIA were increased for any use of pseudoephedrine (odds ratio = 2.0, 95% confidence interval: 1.0, 4.0) and for use of pseudoephedrine in combination with acetaminophen (odds ratio = 3.0, 95% confidence interval: 1.1, 8.0). Reported fever, upper respiratory infection, and allergy were not associated with risks of either defect. These findings add more evidence that aspirin use in early pregnancy increases risk of gastroschisis. Although pseudoephedrine has previously been shown to increase gastroschisis risk, findings of this study raise questions about interactions between medications and possible confounding by underlying illness. Am J Epidemiol 2002;155:26-31.

It is widely accepted that supplementation with folic acid, a B vitamin, reduces the risk of neural tube defects (NTDs). This case-control study tested the hypothesis that multivitamins reduce risks of selected birth defects other than NTDs. Infants with and without birth defects and aborted fetuses with birth defects were ascertained in the greater metropolitan areas of Boston, Philadelphia, and Toronto during 1993-1996. Mothers were interviewed within 6 months after delivery about a variety of factors, including details on vitamin use. Eight case groups were included: cleft lip with or without cleft palate, cleft palate only, conotruncal defects, ventricular septal defects, urinary tract defects, limb reduction defects, congenital hydrocephaly, and pyloric stenosis (n's ranged from 31 to 186). Controls were 521 infants without birth defects (nonmalformed controls) and 442 infants with defects other than those of the cases (malformed controls). Daily multivitamin supplementation was evaluated according to gestational timing categories, including periconceptional use (28 days before through 28 days after the last menstrual period). Odds ratios (ORs) below 1.0 were observed for all case groups except cardiac defects, regardless of control type. For periconceptional use, ORs with 95% confidence intervals that excluded 1.0 were estimated for limb reduction defects using both nonmalformed controls (OR = 0.3) and malformed controls (OR = 0.2) and for urinary tract defects using both nonmalformed controls (OR = 0.6) and malformed controls (OR = 0.5). Statistically significant ORs for use that began after the periconceptional period were observed for cleft palate only and urinary tract defects. These data support the hypothesis that periconceptional vitamin supplementation may extend benefits beyond a reduction in NTD risk. However, other than folic acid's protecting against NTDs, it is not clear what nutrient or combination of nutrients might affect risk of other specific defects.