The abnormalities reported are similar to those seen in humans. Features described include hypertelorism, an abnormal midface, epicanthic folds, microcephaly, transverse palmar creases and minor skeletal abnormalities. However, if seizure control is good, it is probably best to leave the treatment unchanged, provided a single anticonvulsant is used. A literature study supports the view that drug combinations, especially those including sodium valproate, should be avoided. There are various theories which try to explain why anticonvulsant drugs are teratogenic.
Some anticonvulsants have actions on folate metabolism.
Another theory proposes that epoxide formation may be teratogenic. Studies looking at this have found low epoxide hydroxylase activity both in infants with malformations and in their mothers. Pregnancies in women taking these drugs are few but it is likely in the future that these will be the drugs of choice for women of childbearing age. Topiramate, the most recent anticonvulsant to be licensed, is teratogenic in animal studies causing limb and digit reduction. When a woman with epilepsy is pregnant the increased risk of an adverse outcome of pregnancy is shared by the child too.