Colostrum: What Is It?

baby looking at bottle of colostrum

Although breast may be best in the eyes of medicine, not all breast milk is created equal. Your breast milk goes through stages, changing frequently to meet the needs of your growing baby. Research has shown that colostrum, the milk produced during pregnancy and shortly after childbirth, is extremely beneficial to your baby, with lasting effects into adulthood. Colostrum consists of high concentrations of immunoglobulins, maternal antibodies that protect your baby’s immune system, as well as white blood cells, water, protein, fat, minerals, vitamins and carbs.

Commonly referred to as the “first milk,” colostrum is thick, sticky yellow fluid that you produce in significantly smaller amounts before full-on lactation begins. Some breastfeeding moms may worry that their baby isn’t receiving enough food, but don’t be concerned. Although you only produce a few tablespoons of colostrum per feeding, your baby’s stomach capacity is about the size of a small marble (5-7 ml) at one day old. By day three, your newborn baby’s stomach can hold nearly one ounce of fluid, and by day seven your baby’s stomach has doubled in size, holding almost two ounces. Your breast milk production follows a similar cycle, ramping up production to meet your growing baby’s needs.

You begin producing the “first milk” towards the end of your pregnancy and continue producing it until about one week after childbirth. Breastfeeding your baby almost immediately after birth is an amazing bonding experience and ensures that your baby will consume an adequate amount of colostrum during the first few hours of life.

During this time, the intestinal epithelium (the boundary between intestinal tissues and the external environment) is still permeable to large molecules like immunoglobulins, which helps aid in absorption of these powerful maternal antibodies. Colostrum also reduces inflammation, protects against toxins and promotes cell growth, helping your baby generate a non-permeable intestinal membrane to maintain a healthy gastrointestinal tract. Maybe we’re getting a little too technical here -- colostrum helps your baby poo and pass gas.

Sufficient colostrum intake also helps safeguard your baby from infection and build up the immune system. Colostrum contains high concentrations of secretory IgA, the predominant immunoglobulin passed through your breast milk, lactoferrin, which acts as an antibacterial to prevent infection in human infants, and leukocytes, protective white cells. These nutrients help protect your baby from bacteria, viruses and fungi.

Just 36 hours after childbirth, your breast milk starts to transform; you begin producing “mature” milk, which contains more lactose and less sodium, chloride and immunoglobulins, and your milk production increases significantly to accommodate your growing baby. Although mature milk contains less immunoglobulins, your baby is still protected against viruses and bacteria as long as you continue breastfeeding.

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