Animal studies have revealed evidence of developmental toxicity (increased fetal skeletal and visceral abnormalities, and increased embryofetal mortality) when administered at doses similar to, or lower than expected clinical doses. In rats, an increased incidence of hydroureter and/or hydronephrosis have been observed in offspring at all doses, the lowest dose being similar to the maximum recommended human dose on a mg/m2 basis. This drug crosses the human placenta. From the limited amount of data in human pregnancy, it is not possible to inform an associated increased risk of congenital malformations because epilepsy itself and the presence of concomitant antiepileptic medicinal products have their own risks. There are no controlled data in human pregnancy.

To provide information regarding the effects of in utero exposure to this drug, pregnant patients should be encouraged to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll-free number 1-888-233-2334 and must be done by patients themselves. Information on the registry can also be found at the 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 Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D and X are being phased out.

Benefits should clearly outweigh risks

AU TGA pregnancy category: B3
US FDA pregnancy category: Not assigned

Risk Summary: There are no data on the developmental risks associated with use of this drug in pregnant women; in animal studies, developmental toxicity was observed at doses estimated to be similar or lower than those used clinically.

Comments:
-The risk of having a child with a congenital defect as a result of antiepileptic medication is far outweighed by the dangers to the mother and fetus of uncontrolled epilepsy; folic acid supplementation (5 mg) should be started 4 weeks prior to and continued for 12 weeks after conception.
-Women of childbearing potential should receive counseling on the risk of fetal abnormalities with use of antiepileptic drugs (AEDs) during pregnancy; AEDs should generally be continued during pregnancy utilizing monotherapy at the lowest effective dose as this has been shown to minimize risks of fetal abnormalities compared to combination AED therapy.
-A pregnancy exposure registry is available.

See references

With maternal doses up to 2.1 g/day, estimated doses for fully breastfed infants are 0.2 to 1.3 mg/kg/day (equivalent to 1.3 to 3.8% of the maternal weight-adjusted dose). An expert panel has deemed this drug is an acceptable choice for refractory restless leg syndrome during lactation. Until more data becomes available, the developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for this drug and any potential adverse effects on the breastfed infant from this drug or from the underlying maternal condition.

Benefits should clearly outweigh risks

Excreted into human milk: Yes

Comments:
-Breastfed infants should be monitored for drowsiness, adequate weight gain, and developmental milestones, especially when used in combination with other anticonvulsant or psychotropic drugs and in younger, exclusively breastfed infants.
-Some authorities suggest discontinuing nursing or discontinuing use of this drug while breastfeeding due to the potential for serious adverse reactions in the breastfed infant.

See references