Evidence against oral contraceptives as a cause of neural-tube defects.
Information on oral contraceptive (OC) use, collected at the first antenatal visit, was abstracted from the medical notes in respect of 107 index pregnancies resulting in the delivery of an infant with a neural-tube defect (NTD) and 214 unaffected controls. The relative risk of having an NTD infant for women who had at any time used OCs was 0.82 (95% confidence interval 0.52, 1.32) compared with that in women who had never used OCs. For women who stopped OC use less than 3 months before becoming pregnant or who continued in early pregnancy, the relative risk was 1.18 (95% confidence interval 0.70, 1.98) compared with women who had used OCs at any other time. An analysis restricted to those women who had at any time used OCs did not suggest an association between NTD risk and the interval between stopping OC use and becoming pregnant. None of our analyses therefore provided any evidence that OCs cause NTDs and if a risk exists it can only be small.
D000014:Abnormalities, Drug-Induced / Q000209:etiology*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003276:Contraceptives, Oral / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D009436:Neural Tube Defects / Q000139:chemically induced*; D010298:Parity; D012306:Risk; D012923:Social Class; D013997:Time Factors
D003276:Contraceptives, Oral