Can I take lamotrigine while pregnant or breastfeeding?

Breastfeeding during lamotrigine monotherapy does not appear to adversely affect infant growth or development in most infants. Breastfed infants had higher IQs and enhanced verbal abilities than nonbreastfed infants at 6 years of age in one study.[1] Occasional adverse reactions have been reported in infants who receive lamotrigine in milk. Breastfed infants should be carefully monitored for side effects such as apnea, rash, drowsiness or poor sucking, including measurement of serum levels to rule out toxicity if there is a concern. Monitoring of the platelet count and liver function and infant serum concentrations before and after increases in maternal lamotrigine dosage might also be advisable. If an infant rash occurs, breastfeeding should be discontinued until the cause can be established. Infants of mothers taking 150 mg daily or less can undergo less extensive monitoring because they are unlikely to have measurable serum lamotrigine concentrations. If the mother requires lamotrigine, it is not a reason to discontinue breastfeeding. It is important to monitor maternal serum lamotrigine concentration after delivery and adjust the dosage accordingly, because maternal serum levels often increase after delivery. A computer simulation indicated that reducing the dose by 25% weekly for 3 weeks postpartum enabled a stable return to pre-pregnancy exposure. When the postpartum lamotrigine dose exceeded 300 mg daily, closer attention was needed for neonates aged 0 to 4 weeks of age.[2]

“Summary of Use during Lactation”, LactMed record “Lamotrigine” (LM399), quoted verbatim. Everything LactMed reports about Lamotrigine while breastfeeding.

Nursing Mothers Lamotrigine is present in milk from lactating women taking lamotrigine tablets. Data from multiple small studies indicate that lamotrigine plasma levels in human milk-fed infants have been reported to be as high as 50% of the maternal serum levels. Neonates and young infants are at risk for high serum levels because maternal serum and milk levels can rise to high levels postpartum if lamotrigine dosage has been increased during pregnancy but not later reduced to the pre-pregnancy dosage. Lamotrigine exposure is further increased due to the immaturity of the infant glucuronidation capacity needed for drug clearance. Events including apnea, drowsiness, and poor sucking have been reported in infants who have been human milk-fed by mothers using lamotrigine; whether or not these events were caused by lamotrigine is unknown. Human milk-fed infants should be closely monitored for adverse events resulting from lamotrigine. Measurement of infant serum levels should be performed to rule out toxicity if concerns arise. Human milk-feeding should be discontinued in infants with lamotrigine toxicity.

Prescribing label, section “Nursing Mothers” (opening excerpt): Lamotrigine (oral), Alembic Pharmaceuticals Limited. Read the full section on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.