Abstract:Sibelium is a Ca++ channel blocker used as a prophylactic treatment of migraine. No published data exist on the effect of Sibelium on the human fetus during pregnancy or newborn infant following delivery. We report two female siblings who were exposed to Sibelium during fetal life. Both were born with severe neurological depression requiring mechanical ventilation for 5 and 7 days. The findings consisted of hypotonia, hypoventilation/apnea, absent spontaneous movements, absent neonatal reflexes, contractures and skin edema. All the neurological abnormalities reversed by 5 to 7 days. The use of Sibelium during pregnancy can be associated with significant and severe, but reversible, neurological manifestations. The long term effect on neurological development remains concerning but unknown.