Your breast milk starts becoming mature after around two weeks, but it won’t be fully mature milk until your baby’s about four weeks old. It’s probably no coincidence that this stage of breast milk production coincides with the time she starts grabbing objects and putting them.
Breast milk goes through changes from the end of pregnancy through the first few weeks after your baby is born. Colostrum is the first stage, transitional milk is the second stage, and mature milk is the final stage of breast milk. In the beginning, your breast milk starts out as.
breastfeeding~American Academy of Pediatrics (AAP) describes the difference between transitional and mature milk.