Many mood stabilizers increase the risk of birth defects when taken during pregnancy and are often either discontinued or switched to a safer mood stabilizer when a woman is pregnant or trying to become pregnant. However, many pregnancies are unplanned and safer mood stabilizers may not be as effective in some patients.

Because bipolar disorder and other conditions treated with mood stabilizers create their own risks to newborns, it may not be practical to discontinue treatment or change to a new, possibly less effective medication. Ultimately, the physician will weigh the risks to the fetus against the risks posed by the condition. Women who are pregnant or may become pregnant and women who intend to breastfeed should consult a physician before taking mood stabilizers.

Lithium poses a risk of heart defects in the fetus, but these risks may be lower than other medications that may have other birth defect risks or may not be as effective. However, lithium’s effective dosage is close to its toxicity level. Pregnant women who are taking lithium should keep themselves well hydrated, which will help prevent lithium toxicity in the fetus, according to the National Alliance on Mental Illness (NAMI).

Careful monitoring of lithium levels in the blood is important for all patients taking lithium (and other mood stabilizers), but it is especially critical for pregnant women.

Lithium secretes into breast milk and may cause significant damage to the developing kidneys of an infant. It is not recommended for women who are breastfeeding. Women who require lithium following childbirth are recommended to use an alternative to breastfeeding, such as bottle feeding with infant formulas.

Valproate and carbamazepine have been associated with a variety of problems, including nerve conditions and developmental delay. Children exposed to these anticonvulsant mood stabilizers in the womb may display low sugar levels in the blood (hypoglycemia) and liver dysfunction, among other problems. These two medications are considered safe during breastfeeding, though some adverse effects may occur. The bloodwork of an infant nursing from a mother treated with valproate or carbamazepine must be monitored closely. The use of oxcarbazepine, a derivative of carbamazepine, requires further study.

Lamotrigine and topiramate appear to be safe during pregnancy and breastfeeding. No problems in infants exposed to these medications in the womb or through breast milk have been discovered. However, both of these medications are excreted in breast milk and lamotrigine levels in infants can be high.