Evaluation of an association between loratadine and hypospadias--United States, 1997-2001.

Hypospadias is a birth defect that affects approximately seven in 1,000 male infants in the United States. In affected infants, the urethral opening is located along the underside of the penis, scrotum, or perineum; the condition usually is corrected by surgery. Hypospadias is classified in order of increasing severity as first, second, or third degree. In 2002, a study in Sweden noted that among male infants born to women who while pregnant had taken loratadine (Claritin), a nonsedating antihistamine commonly used for seasonal allergies, hypospadias prevalence was twice that of the general population. However, insufficient data were available to determine the severity of the hypospadias cases, and the study did not control for confounding variables (e.g., family history of hypospadias or maternal age). In 2003, a prospective study using data from four countries indicated that five of 142 pregnancies in women exposed to loratadine resulted in infants with major malformations, a prevalence consistent with that of the general population; none had hypospadias. To further assess any potential association between loratadine and hypospadias, CDC analyzed data from the National Birth Defects Prevention Study (NBDPS). This report summarizes the results of that analysis, which determined that no increased risk for second- or third-degree hypospadias existed among women who used loratadine in early pregnancy. These results might be useful for women and health-care providers to address concerns about loratadine use and hypospadias.