The Three Phases Of Breast Milk And What They're Used For

Every new mother is faced with an important decision: to breastfeed or not to breastfeed. Although it's a matter of personal preference, breastfeeding is highly encouraged, as it can decrease a baby's risk of obesity, type 1 diabetes, asthma, sudden infant death syndrome (SIDS), and other health issues, according to the Centers for Disease Control and Prevention (CDC).

While milk production is a very natural process, you could be interested to learn that there's a whole science behind nursing. The let-down reflex is what allows breastmilk to be produced, as described by Pregnancy, Birth & Baby. A baby suckling on the breast triggers the let-down reflex, which releases the hormones prolactin and oxytocin. The release of oxytocin, commonly referred to as the "love hormone," enhances the bond between a mother and her baby, as explained by the World Health Organization (WHO). Eventually, the sound of your baby's cry, or even the sound of another baby's cry, can naturally trigger the let-down reflex. 

There are three stages of breast milk: colostrum, transitional milk, and mature milk, according to the American Pregnancy Association. During pregnancy and immediately after giving birth, a mother's breasts produce colostrum. Transitional milk is produced afterward and gradually changes into mature milk. Each of these unique phases provides a baby with the vitamins and nutrients they need to develop and grow. 

Phase 1: Colostrum

Breastfed babies receive colostrum as their first milk. Lovingly referred to as "liquid gold," colostrum provides a baby with protein, vitamins, minerals, and antibodies that are beneficial for their developing immune system, according to the Cleveland Clinic. The milk contains vitamin A, magnesium, copper, and zinc, and is a yellowish, white, or clear color. Sometimes, colostrum can contain small amounts of blood. 

It's possible for colostrum to leak from your breasts before your baby is even born, since pregnancy hormones trigger its production between 12 and 18 weeks of pregnancy, as described by Grow by WebMD. Pregnant women may begin to experience colostrum leakage during their second trimester

Once your baby is born, colostrum lasts for about two to five days, until your breasts start to produce transitional milk. A newborn baby can benefit from colostrum in a number of ways, as it can improve their gut health, protect them against germs and infections, and help them with their first bowel movement. Additionally, colostrum promotes growth and development in premature babies. 

The slow release of colostrum from the breast allows a baby to learn how to breastfeed. As pointed out by the American Pregnancy Association, a newborn baby's stomach is very small and will continue to grow as breastfeeding progresses in the upcoming weeks. The 1-4 teaspoons of colostrum you produce each day will be sufficient for your newborn. 

Phase 2: Transitional milk

As you and your baby become more accustomed to breastfeeding, the colostrum you were producing changes into transitional milk. Transitional milk is produced in larger quantities than colostrum and usually begins around two to five days after birth, according to MomJunction. The milk contains more calories, fat, and sugar than colostrum, and is usually a bluish-white or creamy-yellow color. However, the color of your transitional milk can vary based on the medications you take, the food you eat, and other factors. As your transitional milk begins to change into mature milk, it can become more of a white color. 

Professor Peter Hartmann, an expert on breast milk composition from the University of Western Australia, told Medela that transitional milk contains fatty acids and lactose that provide energy to a baby. In addition, transitional milk contains protein and amino acids that promote the development of a baby's brain, eyes, and other essential organs. 

During this stage, it's normal for your breasts to become enlarged, swollen, and painful. This happens when your breasts accumulate more blood and fluid in order to produce breast milk. As explained by HealthyChildren, the hardening and swelling of your breasts could make it more difficult for your baby to latch on and breastfeed. If necessary, your pediatrician or a lactation specialist can help you and your baby become more comfortable breastfeeding during this stage. 

Phase 3: Mature milk

Your breasts will start producing mature milk by approximately four weeks after childbirth, according to Welcome Baby Care. Your previously firm and swollen breasts may become softer again during the mature milk stage, as pointed out by Healthline. Mature milk is less sticky and thinner than colostrum and is divided into two distinct stages: Foremilk is the stage that occurs when you begin a breastfeeding session, while hindmilk follows shortly after. Foremilk contains less fat and tastes sweeter than hindmilk. 

Most of the nutrients provided by mature milk come from hindmilk. Like colostrum and transitional milk, mature milk strengthens your baby's immune system and contains nutrients that benefit the brain. As noted by Medela, your baby's appetite is controlled by the hormones in mature milk, which may be a protective factor against excessive weight gain. Stem cells are also found in mature milk, which are a special type of cell that can transform into any other type of cell in the body. 

In some cases, women who give birth prematurely or by cesarean section (C-section) may experience milk production delays. Other factors, like being under extreme stress or having diabetes or polycystic ovary syndrome (PCOS), could also affect the production of mature milk. You can receive support and guidance from a lactation consultant if you're experiencing milk production delays.