Objectives: To examine, in Western Australian women, pregnancy use of drugs that have been found to be associated with birth defect risks in other studies.
Design: Data were used from a retrospective study of birth defects in which mothers were sent questionnaires asking about a variety of pregnancy events and exposures, including specific questions on medication use.
Population: Case subjects were fetuses or infants with structural birth defects born in Western Australia from 1997 to 2000, identified from the Western Australian Birth Defects Registry. Control subjects were infants without birth defects, randomly selected from the Western Australian Midwives’ Notification System.
Measures: First trimester uses of corticosteroids, medications that antagonise folic acid metabolism, and vasoactive drugs were compared between case and control mothers.
Results: The mothers of 2.5, 2.4, and 1.9% of controls, cases, and oral cleft cases, respectively, reported corticosteroid use. The mothers of 0.6% of controls and 1.4% of cases used a folic acid antagonising medication, yielding an odds ratio of 2.3 (95% confidence interval, 0.58–9.4). The mothers of 4.5% of controls and 7.1% of cases used a vasoactive drug (pseudoephedrine, aspirin, ibuprofen, amphetamine, cocaine, or ecstasy). Cigarette smoking is also vasoactive. For exposure to both a vasoactive drug and cigarette smoking, the birth defect risk was 3.0 (0.92–9.6).
Conclusions: There was no difference in corticosteroid use between case and control mothers, although the number of exposed subjects was small. Odds ratio estimates for folic acid antagonists and vasoactive agents support previously reported associations, but they were not statistically significant.