Exposure to trimethoprim/sulfamethoxazole but not other FDA category C and D anti-infectives is associated with increased risks of preterm birth and low birth weight

SummaryObjectiveTo examine the association between trimethoprim/sulfamethoxazole, other US Food and Drug Administration (FDA) C and D anti-infectives, and non anti-infective FDA C, D, and X drugs used during pregnancy with preterm birth and low birth weight.MethodsWe carried out a retrospective cohort study based on a 50% random sample of women who gave birth in the Canadian province of Saskatchewan from 1997 to 2000. The association between trimethoprim/sulfamethoxazole, other FDA C and D anti-infectives (fluconazole, clarithromycin, doxycycline, and tetracycline), and non anti-infective FDA C, D, and X drugs used during pregnancy with preterm birth and low birth weight was evaluated using multiple logistic regression, with adjusted odds ratios (aORs) and 95% confidence intervals (CIs) as association measures.ResultsA total of 17 939 women were included in the final analysis. Trimethoprim/sulfamethoxazole was associated with significantly increased risks for preterm birth (aOR 1.51, 95% CI 1.10, 2.08) and low birth weight (aOR 1.67, 95% CI 1.14, 2.46). Exposure to non anti-infective FDA category C, D and X drugs was also associated with increased risks for preterm birth (aOR 1.17, 95% CI 1.09, 1.31) and low birth weight (aOR 1.14, 95% CI 0.92, 1.42), but to a lesser degree. Other FDA C and D anti-infectives were not (statistically) significantly associated with increased risks for preterm birth (aOR 0.93, 95% CI 0.49, 1.77) or low birth weight (aOR 0.65, 95% CI 0.27, 1.60).ConclusionsAmong FDA C, D and X drugs, trimethoprim/sulfamethoxazole, a folic acid antagonist, has the strongest association with preterm birth and low birth weight.