What Is Colostrum?

Kelly Anne Spratt, D.O., Director of Women's Cardiovascular Health at the University of Pennsylvania Presbyterian Medical Center, answers your questions.

Q. What is colostrum?

A. Colostrum is the thin, yellowish discharge that some pregnant women may notice leaking from their breasts. It is not milk but pre-milk. It is richer in protein and lower in fat and milk sugar than breast milk. Most women don't secrete colostrum until after delivery. This is often the first bit of liquid that is released after a baby is born and is very important to the baby since it contains antibodies that may be important in protecting the baby against diseases. In addition, colostrum contains certain fatty acids and protein vital to brain growth. Human breast milk has a higher ratio of calcium than cow's milk. Colostrum also helps infants to empty the digestive system of excess mucus and meconium (the baby's first stool). Even women who choose not to breastfeed for long should give this vital colostrum to her infant for the first few days.

Do not be concerned if your breasts don't fill with actual milk right after delivery, since this may not happen for three or four days after delivery and after colostrum has stopped flowing.