Short-acting sulfonamides near term and neonatal jaundice.

OBJECTIVE To investigate the association between maternal use of sulfamethizole near term and the risk of neonatal jaundice. METHODS We conducted a nationwide population-based retrospective cohort study using Danish registers. All Danish women giving birth between 1995 and 2007 were included from the Danish Fertility Database. Women redeeming a prescription for sulfamethizole up to 4 weeks before giving birth were identified from the National Prescription Register. The primary outcome was the number of neonates diagnosed with jaundice between birth and age 28 days identified in the National Hospital Register. Risk of neonatal jaundice was calculated as odds ratios (ORs) with linear logistic regression with and without adjustment for confounders. RESULTS We identified 841,900 births. Of 1,823 (0.2%) neonates exposed to sulfamethizole up to 4 weeks before birth, 197 (10.8%) developed neonatal jaundice. The OR of developing neonatal jaundice after exposure to sulfamethizole was 2.35 (95% confidence interval [CI] 2.02-2.72). Adjustment for maternal age, education, household income, parity, and period of conception left OR unchanged at 2.29 (95% CI 1.97-2.67). After further adjustment for gestational age, the risk associated with sulfamethizole was rendered insignificant (OR 1.03, 95% CI 0.86-1.22). Narrowing exposure time to the last week before birth did not change the estimates. Broken into gestational age groups, the rate of neonates with jaundice after exposure was similar to the rate of unexposed neonates with jaundice. CONCLUSIONS We found no association between redeeming a prescription of sulfamethizole near term and increased risk of neonatal jaundice. We showed that the presumed association is the result of preterm birth, which can be caused by maternal urinary tract infection. LEVEL OF EVIDENCE II.