Lamivudine has been well studied in HIV-positive nursing mothers and appears to be well tolerated by their breastfed infants. It has not been studied in HIV-negative nursing mothers being treated for hepatitis B infection, but the low doses used would not be expected to cause any serious adverse effects in breastfed infants. The manufacturer estimates that a breastfed infant's dose would be about 6% of the infant dose for children over 2 years of age. Achieving and maintaining viral suppression with antiretroviral therapy decreases breastfeeding transmission risk to less than 1%, but not zero. Individuals with HIV who are on antiretroviral therapy with a sustained undetectable viral load and who choose to breastfeed should be supported in this decision. If a viral load is not suppressed, banked pasteurized donor milk or formula is recommended.[1,2] Extended postnatal prophylaxis of breastfed infants with lamivudine should continue until breastfeeding is stopped.[3]
An expert review of available data concluded that there is currently no justification for contraindicating the use of lamivudine for hepatitis B therapy during breastfeeding.[4] Some professional organization guidelines allow breastfeeding during lamivudine therapy, although one guideline cautions against it because of a lack of long-term safety data.[5-7] The lack of long-term safety data with long-term, low-level infant exposure should be discussed with the mother.[5] No differences exist in infection rates between breastfed and formula-fed infants born to hepatitis B-infected women, as long as the infant receives hepatitis B immune globulin and hepatitis B vaccine at birth. Mothers with hepatitis B are encouraged to breastfeed their infants after their infants receive these preventative measures.[8,9]