Why Breast Milk
From the moment your baby is born, your body starts producing the perfect mix of nutrients in your breast milk for him. While formula contains essential vitamins and proteins that a baby needs, it doesn't have all the benefits of breast milk, such as antibodies that strengthen your baby's immune system.
It's good for your baby. Research shows that breastfed babies are significantly less likely to suffer from ear infections, vomiting, diarrhea, pneumonia, asthma, diabetes, and urinary-tract infections, as well as from food allergies and eczema if your family has a history of either. Nursing may also boost babies' brainpower. Mother's milk also helps protect babies from becoming obese later in life, and girls who are breastfed are also less likely to develop breast cancer as adults.
It's good for you. Oxytocin, a hormone released during nursing, helps to return your uterus to its regular size more quickly and reduces postpartum bleeding. Breastfeeding also burns about 500 calories a day, which can help you lose your baby weight faster. And women who nurse are at lower risk of developing breast cancer, rheumatoid arthritis, and possibly osteoporosis. Not to mention that breastfeeding is convenient (no bottles to wash or formula to mix) and cheaper than formula (you need only a few nursing bras and a breast pump).
How milk adjusts for your baby's needs
At birth: Your first milk is colostrum, a thick, yellowish pre-milk that's high in the fats and proteins your newborn needs and easy for her to digest. It's also extremely rich in the substances that protect her against infections.
Two to five days after birth: Your milk will begin to "come in" now. This transitional milk is thinner than colostrum but far more plentiful, and higher in lactose and fat, which help your baby's brain develop. Your breasts will feel their largest and firmest now. You'll begin to feel your milk "let down," or move through your breasts - often described as a pins-and-needles sensation.
Two weeks after birth: Your milk will become even thinner and more watery, but it's still rich in nutrients. Your breasts will probably feel smaller and softer now. Mature milk becomes fattier over the course of a feeding (the first part is mainly water), so allow your baby to drink for about ten minutes before you switch to the other breast.