Most medications, including lithium, the anticonvulsants, and the antipsychotics, will make their way into breast milk. The level to which each medication is found in the breast milk varies.
If a woman taking medication intends to breast feed, depending on her specific medications, additional monitoring of both mother and baby will be required. The type of monitoring will relate directly to the medications, i.e., if a woman on lithium is breast feeding it will be important to monitor lithium levels and other blood work in the infant, and to educate the parents about warning signs of toxicity in their child.
Because maintaining healthy sleep cycles is so important in bipolar disorder, getting up to breast feed every two to three hours may be too disruptive and will make a woman more susceptible to a mood episode. The use of a breast pump and a spouse, or someone else, to handle nighttime feedings will make sense.