Breastfeeding social reactions in the English-speaking world. It is possible for a mother to continue breastfeeding an older sibling while also breastfeeding a new baby; this is called "tandem nursing". During the late stages of pregnancy, the milk changes to colostrum. While some children continue to breastfeed even with this change, others may wean. Most mothers can produce enough milk for tandem nursing, but the new baby should be nursed first for at least the first few days after delivery to ensure that it receives enough colostrum. Breastfeeding triplets or larger broods is a challenge given babies' varying appetites. Breasts can
Colostrum lysozyme, lactoperoxidase, complement, and proline-rich polypeptides (PRP). A number of cytokines (small messenger peptides that control the functioning of the immune system) are found in colostrum as well, including interleukins, tumor necrosis factor, chemokines, and others. Colostrum also contains a number of growth factors, such as insulin-like growth factors I (IGF-1), and II, transforming growth factors alpha, beta 1 and beta 2, fibroblast growth factors, epidermal growth factor, granulocyte-macrophage-stimulating growth factor, platelet-derived growth factor, vascular endothelial growth factor, and colony-stimulating factor-1. Notably in humans a lack of colostrum production is linked to a mutation in the ABCC11 gene that occurs