Colostrum is the first breast milk a mother produces for her newborn baby. Colostrum is generally available in the breasts already when the baby is born, and some mothers may leak colostrum or find dried crystals on the nipples in the weeks or days before birth. Colostrum, a rich yellow in color, is often called “liquid gold” in recognition of its essential function to newborn babies.

Colostrum is the Perfect First Food

Colostrum is easily digestible for newborns, and is rich in protein and immunities. The volume of available colostrum is low – about 5-7 ml (a little more than a teaspoon) in each breast. Since a baby’s stomach capacity at birth is only about the volume of a marble, this is perfect.

Colostrum is thick and contains incredibly concentrated nutrition. Nature makes it intentionally slow- flowing, not only to accommodate baby’s small stomach capacity, but also to ensure that it requires a great deal of suckling to remove it, providing the breast stimulation that new mothers need to send the brain signals to begin producing “mature” milk on about day 3-5.

Colostrum is Important for Newborns

Colostrum is incredibly important to newborns. Because the volume of colostrum is small, some assume that it is not enough food for a baby or that it’s not that important for a baby to nurse until mature milk is present – this is completely incorrect. Nursing very frequently in the first several days after birth both delivers the many essential benefits of colostrum, but also signals the body to begin that mature milk.

Colostrum has very specific functions in the newborn gastrointestinal system. According to the La Leche League, colostrum has a protective effect on the intestines, coating the GI tract with a “barrier” that prepares the intestines for the new substances that will come into the mother’s mature milk from her diet and environment. Colostrum also acts as a laxative, helping the newborn clear his or her system of meconium, the black, tarry stools in the first days of life. Clearing the meconium is critical in removing bilirubin and preventing exaggerated jaundice (see my related article, Colostrum and Jaundice).

Colostrum also contains immunities from the mother, to supplement those received in utero. For this reason, colostrum is often called babies’ first immunization. In many non-human mammals, newborns will actually die without the immunities from colostrum, because they do not receive any before birth. While this is thankfully not the case with humans, it illustrates just how important the immunities in colostrum can be. While colostrum may not be the exclusive source of immunities for human babies, these immunities are no less valuable.

Colostrum is the First Milk

Over the first days and weeks of life, colostrum will transition into “mature milk.” It is important to note that the term mature milk, which commonly describes the thinner, whiter, higher-volume milk that begins production a few days after birth should not imply that colostrum is in any way “immature” or less important. While many refer to the change in volume as the milk “coming in,” many lactation professionals take issue with this language, because colostrum is milk – merely the first stage that meets the needs of the newborn in its first days.

When mature milk begins to fill the breasts, the color will transition over several hours or days from yellow to white (actually, many see a bluish tint to mature breast milk and the color can subsequently be affected by what you eat!) Once the mature milk is produced, it too will change over time in composition to meet the needs of the growing baby, even if not as noticeable in appearance as the shift from colostrum.

Colostrum is a truly amazing miracle of nature and since it is only present for the first days of a baby’s life, it is especially important to get a baby latched on correctly and nursing as quickly as possible. Hospitals need to support frequent nursing by new mothers, to help mothers establish breastfeeding starting with the first feed and to keep administrative needs from interfering with breastfeeding. Many women don’t understand the importance of the colostrum or of early frequent nursing in establishing successful breastfeeding.

If babies are unable to breastfeed, or there are difficulties in early nursing colostrum can be expressed. Many women report better success with expressing colostrum by hand than by pump. If the baby is not medically restricted from food by mouth, the colostrum can be fed on a clean finger or by medicine dropper or syringe. The more available colostrum the baby receives, the better.