<P> Benefits for the mother include less blood loss following delivery, better uterus shrinkage, and less postpartum depression . Breastfeeding delays the return of menstruation and fertility, a phenomenon known as lactational amenorrhea . Long term benefits for the mother include decreased risk of breast cancer, cardiovascular disease, and rheumatoid arthritis . Breastfeeding is less expensive than infant formula . </P> <P> Health organizations, including the World Health Organization (WHO), recommend breastfeeding exclusively for six months . This means that no other foods or drinks other than possibly vitamin D are typically given . After the introduction of foods at six months of age, recommendations include continued breastfeeding until at least one to two years of age . Globally about 38% of infants are only breastfed during their first six months of life . In the United States, about 75% of women begin breastfeeding and about 13% only breastfeed until the age of six months . Medical conditions that do not allow breastfeeding are rare . Mothers who take certain recreational drugs and medications should not breastfeed . Smoking, limited amounts of alcohol, or coffee are not reasons to avoid breastfeeding . </P> <P> Changes early in pregnancy prepare the breast for lactation . Pre-birth hormone levels become altered after the birth and stimulate the production of milk . From around halfway through pregnancy, the breasts begin to produce colostrum . Colostrum, a thick yellowish fluid rich in protein, continues to be produced for the first few days after delivery . Around 30 to 40 hours after delivery, the composition of milk changes to mature milk and milk volume becomes copious, an event known as the milk "coming in". Sucking causes the pituitary to release oxytocin that causes to the contraction of the uterus . Progesterone is the hormone that influences the growth of breast tissue before the birth . The postpartum changes that occur in the endocrine system after the birth shift from hormones that prevent lactation to hormones that trigger milk production . This can be felt by the mother in the breasts . The crying of the infant can induce the release of oxytocin from the pituitary gland . </P> <P> Not all of breast milk's properties are understood, but its nutrient content is relatively consistent . Breast milk is made from nutrients in the mother's bloodstream and bodily stores . Breast milk has an optimal balance of fat, sugar, water, and protein that is needed for a baby's growth and development . Breastfeeding triggers biochemical reactions which allows for the enzymes, hormones, growth factors and immunologic substances to effectively defend against infectious diseases for the infant . The breastmilk also has long - chain polyunsaturated fatty acids which help with normal retinal and neural development . </P>

When does a woman's body produce milk