Pregnancy outcome after gestational exposure to terfenadine: A multicenter, prospective controlled study

Background: Terfenadine is a selective, nonsedative, H-1-blocker antihistam ine used for a variety of allergic conditions, The widespread popularity of terfenadine and its use by many women in their reproductive age raises con cerns regarding its safety during pregnancy. Presently, no prospective cont rolled study has addressed its safety during gestation, Objective: We sought to determine whether terfenadine use during pregnancy is associated with an increased risk of major malformations, decreased birt h weight, perinatal complications, or developmental delays, Methods: A multicenter, prospective controlled study was per formed. Pregna nt women exposed to terfenadine during gestation were matched with control subjects exposed to drugs not known to adversely affect pregnancy outcome, The primary end point was the incidence of major malformations. Secondary o utcomes of interest were pregnancy outcome, rates of preterm delivery, birt h weight, and developmental milestones. Results: One hundred eighteen women were exposed to terfenadine during preg nancy, Among those exposed during the first trimester (n = 65), rates of ma jor malformations in the terfenadine group did not differ from rates in the ir matched control subjects (0% vs 2%; relative risk, 0.57; 95% confidence interval, 0.06-5.39; P = .53), The birth weight in the terfenadine-exposed newborns was significantly lower compared with that in their matched contro l subjects (3335 +/- 582 vs 3499 +/- 617 g; P = .04), However, the rates of birth weight below 2500 g and birth weight below the 10th percentile for g estational age were not different between the groups. Univariate and multip le regression analysis revealed that none of the terfenadine therapy-relate d factors (daily dose, duration of therapy, and trimester of exposure) had a significant predictive effect on birth weight, Gestational age at deliver y, rates of preterm deliveries, and developmental milestones sere comparabl e between the groups. Conclusions: On the basis of the limited sample size of this study, it appe ars that terfenadine is not associated with a 6-fold or greater increased i ncidence of major malformations. Terfenadine use during gestation was not a ssociated with increased rates of prematurity or developmental delays. Furt her studies n ill be needed to confirm the finding of lower birth weight in newborns exposed to terfenadine.