Supplements Post module evaluation References Breast milk changes in appearance and composition during the months of breastfeeding as the photo below illustrates. Colostrum is a thick, yellowish milk that is secreted by a woman's breast in the first several days after delivery. It has increased concentration of calcium, potassium, proteins, fat-soluble vitamins, minerals and antibodies. Due to its high concentration of antibodies, this milk is particularly valuable for infants in preventing infection.
Transitional milk is secreted between about four days and ten days postpartum.
It is intermediate in composition in between colostrum and mature milk. The volume increases during this time.