Prenatal exposure to loratadine in children with hypospadias: a nested case-control study within the Danish National Birth Cohort.

The aim of this study was to examine the risk of hypospadias after reported exposure to loratadine and other antihistamines during pregnancy, based on data from the Danish National Birth Cohort. We examined the risk of hypospadias in a nested case-control design based on women enrolled in the Danish National Birth Cohort from 1998 to 2002 ( approximately 95,000 pregnant women). Data on maternal use of medicine in pregnancy were retrieved from questionnaires and telephone interviews, and data on birth outcomes were obtained from the Hospital Discharge Registry (HDR). Within the Danish National Birth Cohort, we identified cases with a diagnosis of hypospadias and randomly selected 10 controls per case without such a diagnosis (matched by date of birth). We identified 203 cases of hypospadias recorded in the HDR within 1 year postpartum and 2030 controls. One case (0.5%) and 25 (1.2%) controls reported exposure to loratadine in the first trimester or up to 30 days before the time of conception. The adjusted odds ratio (OR) for hypospadias among users of loratadine relative to nonusers was 0.9 (95% CI: 0.1-6.9) and the corresponding OR for other antihistamines was 0.5 (95% CI: 0.1-1.9). These data do not indicate an increased risk of hypospadias associated with maternal exposure to loratadine. In addition, this study does not suggest any risk differential between maternal exposure to loratadine and other antihistamines. However, the statistical precision of the risk estimates was low.