Your body is able to produce some milk by the fourth or fifth month of pregnancy. You will notice how your breasts swell and become heavier the nearer you are to the delivery date. Your body goes through all the preparation needed before delivery that ensures that under normal conditions, you are able to give your baby his first feeding right after delivery.
The milk that is produced during the first few days of your baby's life is referred to as colostrum, or first milk. By the third or fourth day, your milk changes in consistency and becomes mature milk. The quantity produced increases dramatically.
Breastmilk contains everything your baby needs to be nourished. It also contains extra ingredients that help protect your baby from infections and illnesses in the ears, lungs and bowel. There is also evidence that breastfed babies have a lower risk of obesity and allergy development in later life.