Sulfonamides and Nitrofurantoin Associated with Birth Defects

The New York Times is reporting on this study by Crider KS et al. in November’s Archives of Pediatrics and Adolescent Medicine which appears to demonstrate an association between certain antibiotics taken for urinary tract infections (used just prior to pregnancy or during the first trimester of gestation) and several common birth defects.

The antibiotics associated with the most pronounced increases in birth defects were nitrofurantoin and the sulfonamides. Caution is in order when interpreting these results. First, it appears that the exposures were extrapolated from memory rather than measured quantitatively. Questionnaire epidemiology is notoriously prone to error. Second, there’s the question of where does the arrow of causal suspicion point. Maybe it’s the infection that’s responsible for the birth defects. Finally, this particular cohort would not appear to be a cross section of pregnant American women but instead is drawn from a narrower slice and is significantly homogeneous. Social structures and interactions are increasingly recognized as important independent causes of certain morbidities.