Animal studies have shown evidence of developmental toxicity including teratogenic effects at doses similar to, or greater than expected human doses. Postmarketing data from several prospective pregnancy registries have not shown a substantial risk for major congenital malformations in over 1000 women exposed to this drug as monotherapy during the first trimester, although a teratogenic risk cannot be completely excluded. Studies have shown risks to mother and fetus with uncontrolled epilepsy during pregnancy. There are no adequate and well-controlled studies in pregnant women.

Gradually decreasing plasma levels of this drug may occur through pregnancy with the decrease being most pronounced during the third trimester; closely monitor plasma levels during pregnancy and postpartum, especially if the dose was changed during pregnancy.

A pregnancy registry is available to provide information on the effects of in utero exposure; physicians should encourage pregnant patients to enroll in the North American Antiepileptic Drug (NAAED) pregnancy registry: Website: http://www.aedpregnancyregistry.org/.

AU TGA pregnancy category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

Benefit should outweigh risk

AU TGA pregnancy category: B3
US FDA pregnancy category: C

Comments:
-Monotherapy is preferred whenever possible.
-Plasma drug levels should be monitored closely during pregnancy and through the postpartum period
-Women on antiepileptic drugs (AEDs) should receive pre-pregnancy counseling regarding the risk of fetal abnormalities; folic acid supplementation is recommended.
-Sudden discontinuation of AEDs should be avoided during pregnancy as this could have serious consequences for the women and her unborn child.

See references

Benefit should outweigh risk

Excreted into human milk: Yes

Comment:
-Monitor breastfed infant for drowsiness, adequate weight gain, and developmental milestones, especially those who are younger, exclusively breastfed, and exposed to more than 1 anticonvulsant.

Maternal doses of up to 3500 mg/day have been shown to produce low levels in breast milk. One author estimates that a fully breast fed infant would receive 7.9% of the maternal weight-adjusted dose based on 11 women providing milk samples. Some authorities suggest that if therapy with this drug is required by the mother, it is not a reason to discontinue breastfeeding. Close monitoring of the infant is warranted. Maternal serum level monitoring and dosage adjustment is advisable in the early postpartum period if the drug was taken throughout pregnancy and breastfeeding. There is some evidence to suggest that this drug might reduce the maternal breastmilk supply in some women. The manufacturer recommends women do not breastfeed during therapy because of the potential for serious adverse reactions in nursing infants.

See references