Risk of congenital anomalies in pregnant users of non-steroidal anti-inflammatory drugs: A nested case-control study.

BACKGROUND: Many women take non-steroidal anti-inflammatory drugs (NSAIDs) during pregnancy but the risks for the infant remain controversial. We carried out a study to quantify the association between those women prescribed NSAIDs in early pregnancy and congenital anomalies.

METHODS: A population-based pregnancy registry was built by linking data from three administrative databases in Quebec between 1997-2003. The inclusion criteria were mothers of live singleton infants, between 15-45 years of age, covered by the RAMQ drug plan > or =12 months before and during pregnancy, and prescribed an NSAID or other medications during pregnancy. We selected as cases infants with any congenital anomaly (ICD-9; 740-759) diagnosed in the first year of life. Up to 10 controls, defined as infants with no congenital anomalies detected were selected for each case. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated.

RESULTS: Within the registry, 36,387 pregnant women met the inclusion criteria. We identified 93 births with congenital anomalies in 1056 women (8.8%) who filled prescriptions for NSAIDs in the first trimester of pregnancy, compared to 2478 in 35,331 (7%) women who did not. The adjusted OR for any congenital anomalies for women who filled a prescription for NSAIDs in the first trimester was 2.21 (95% CI = 1.72-2.85). The adjusted OR for the anomalies related to cardiac septal closure was 3.34 (95% CI = 1.87-5.98). There were no significant associations with anomalies of other major organ systems.

CONCLUSIONS: Our study suggests that women prescribed NSAIDs during early pregnancy may be at a greater risk of having children with congenital anomalies, specifically cardiac septal defects.