Seizure disorders may impair fertility. But certain anticonvulsants may make oral contraceptives less effective, resulting in unintentional pregnancy.
The dose of anticonvulsant drugs may have to be increased during pregnancy to maintain therapeutic levels. If women get enough sleep and anticonvulsant levels are kept in the therapeutic range, seizure frequency does not usually increase during pregnancy, and pregnancy outcome is good; however, risks of preeclampsia, fetal growth restriction, and stillbirth are slightly increased. Generally, uncontrolled seizures are more harmful during pregnancy than is use of anticonvulsants; thus, the top priority of treatment during pregnancy is to control seizures. Preconception consultation with a neurologist is recommended to stabilize maternal seizures before pregnancy; the lowest possible dose of anticonvulsant should be used.
Anticonvulsants slightly increase risk of congenital malformations and may tend to slightly decrease intelligence in offspring; risk of intellectual disability may be increased. Risk of hemorrhagic disease of the newborn (erythroblastosis neonatorum) may be increased by in utero exposure to certain anticonvulsants (eg, phenytoin, carbamazepine, phenobarbital); however, if prenatal vitamins with vitamin D are taken and vitamin K is given to the neonate, hemorrhagic disease is rare.
Taken during pregnancy, phenobarbital may reduce the physiologic jaundice neonates commonly have, perhaps because the drug induces neonatal hepatic conjugating enzymes. Phenytoin is generally preferred.
All anticonvulsants increase the need for supplemental folate; 1 mg po is given once/day. Ideally, it is started before conception.
Vaginal delivery is usually preferred, but if women have repeated seizures during labor, cesarean delivery is indicated. Anticonvulsant levels can rapidly change postpartum and should be closely monitored then.
Last full review/revision December 2008 by Sean C. Blackwell, MD
Content last modified October 2010