Erythromycin use during pregnancy in relation to pyloric stenosis.

Abstract

Newborn infants treated with erythromycin may be at risk for developing pyloric stenosis. Because erythromycin is known to cross the placenta and is a recommended treatment for chlamydia and other infections in pregnancy, we explored whether erythromycin taken during pregnancy might similarly lead to an increase in risk of pyloric stenosis. We used data collected between 1976 and 1998 as part of an ongoing case-control surveillance program. Cases were 1044 infants with a diagnosis of pyloric stenosis. Two control groups were used: 1704 nonmalformed infants and 15,356 infants with a wide range of other malformations. Odds ratios and 95% CIs were calculated by using data from each control group. All odds ratio estimates are close to 1.0, all CIs include 1, and all upper 95% confidence bounds are less than 2.0. We found no evidence of an increased risk of pyloric stenosis among infants born to mothers exposed to erythromycin during pregnancy.