Prenatal closure of the ductus arteriosus (DA) is associated with maternal ingestion of cyclooxygenase inhibitors during pregnancy. We report a case of prenatal DA closure after maternal ingestion of MonaVie, a juice blend containing the cyclooxygenase and nitric oxide synthase inhibitors anthocyanins and proanthocyanidins. A G(2)P(0)Ab(1) woman had an uncomplicated first and second trimester and normal 20-week fetal ultrasound. At 37 weeks, she developed polyhydramnios; a fetal echocardiogram showed right atrial and ventricular (RV) enlargement with RV dysfunction. Immediately after birth, there was pulmonary hypertension by echocardiogram with DA closure, severe RV hypertrophy and dysfunction, and marked right-to-left atrial shunting. Improvement occurred over 3 weeks with the neonate tolerating room air and a follow-up echocardiogram showing minimal atrial shunting and improved RV function. This report shows an association between MonaVie ingestion throughout pregnancy and prenatal DA closure resulting in cardiac dysfunction and pulmonary hypertension at birth.