20 May 2019 Milk is produced in the mammary gland. During pregnancy , the parts of the mammary gland responsible for milk production undergo major development and acquire the ability to produce milk. However, until the baby's birth, this production is prevented by hormones that are at high levels in the mother's bloodstream during pregnancy. After childbirth , the blood levels of these hormones go down and the mammary gland begins to produce milk continuously. The gland stores it until it is removed by the baby when breast feeding or otherwise. The ideal food for the baby Breast milk is a complete food for the baby. In addition to its nutritional value, it has important immunological properties. Nutritional value Breast milk is rich in nutrients that promote the baby's normal growth and development; The composition of breast milk changes during lactation so that it can meet the baby’s needs; It has a balanced components of proteins, carbohydrates, minerals and other nutrients; Milk contains the water necessary to keep the baby well hydrated; Breast milk is the most easily digestible food the baby can receive. The high bioavailability of breast milk nutrients results in better digestion, absorption and use; Breast milk also helps the development in the child's intestine of Lactobacillus, microorganisms that ferment milk carbohydrate (lactose) making stools more frequent and softer, especially in the first two weeks of life. These micro-organisms also prevent the establishment of other bacteria that can cause diarrhoea. Immunological properties The immunological properties of breast milk are due to its composition. Breastfed babies have significantly fewer gastrointestinal, respiratory and urinary infections. Breast milk antibodies directly protect against the infection that produced them. There are also other anti-infectious factors in the milk that create an environment friendly to normal flora and hostile to harmful flora. Breast milk also helps the development of the baby's immune system. This article was written with the support of physicians and other clinical professionals from the Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.