However, in August of 2013, Andersen et al from Denmark presented a second study using the same Danish registries covering more years (1997-2010) and more pregnant women . In contrast to Pasternak et al, Andersen’s study detected a 2-fold increased risk of cardiac malformations with ondansetron , leading to an overall 30% increased risk of major congenital malformations. To rule out confounding by indication, Andersen et al9 also examined metoclopramide taken for morning sickness, detecting no increase in teratogenic risk.
The fact that the same large registry can be investigated to yield such opposing results is concerning. There is an exponential rise in use of prescription database linkage to birth registries. None of these were designed specifically to address fetal drug safety, and there may be flaws in the quality and completeness of the available data.
Of potential importance, a recent large case control study by the Sloan epidemiology unit and the Centers of Disease Control and Prevention, has reported a 2-fold increased risk for cleft palate associated with ondansetron taken for NVP in the first trimester of pregnancy