One in 600 babies born will be born with a cleft lip or palate. During normal fetal development between the 6th and 11th week of pregnancy, the clefts in the lip and palate fuse together. In babies born with cleft lip or cleft palate, one or both of these splits failed to fuse.
Contrary to popular belief, this craniofacial malady has more than cosmetic consequences. A cleft palate can range from a small ridge in the upper lip which results in minimal problems to a large separation of the palate that interferes with eating, speaking, and even breathing.
The larger the separation, the greater the possible effects of the condition. Common ongoing effects of cleft lip and palate include: nasal obstruction, sleep apnea, sinusitis, laryngitis, rhinitis, and progressive hearing loss.
According to the North American Antiepileptic Drug Pregnancy Registry, Birth defects, such as, cleft palate/cleft lip occurred in 1.4% of newborns that had been exposed to Topamax. Newborns of mothers who didn't exhibit epilepsy or take anti-epilepsy drugs demonstrate a rate of 0.07%. This data indicates that infants whose mothers took Topamax are 21 times more likely to have Topamax birth defects, then normal.
Topamax has also been linked to congenital defects of the heart, brain, lung, and limbs. In March of 2011 the FDA issued a warning on Topamax and changed its pregnancy category from C to D indicating a Topamax birth defect complication. The new label states “there may be an association between the use of Topamax during pregnancy and congenital malformations.”