Minimal information is available on the clinical use of avalglucosidase during breastfeeding. Because avalglucosidase is a large protein molecule with a molecular weight of about 124,000 Da, the amount in milk is likely to be very low.[1] It is also likely to be partially destroyed in the infant's gastrointestinal tract and absorption by the infant is probably minimal.[2] One infant breastfed during maternal avalglucosidase therapy beginning at 2 months postpartum with no apparent adverse effects.