Mature Breast Milk

Definition and Information

Mature Breast Milk: Definition and Information
Mature breast milk is the final stage of breast milk.. Image Source/Getty Images

What Is Mature Milk?

Breast milk goes through changes from the end of pregnancy through the first few weeks after your baby is born. These changes are often called stages or phases. Colostrum is the first stage, transitional milk is the second stage, and mature milk is the final stage of breast milk.

When Will You Start Making Mature Breast Milk?

In the beginning, your breast milk starts out as colostrum.

Then, in the first few days after your baby is born, it will begin to change, or transition over to mature milk. As your mature milk starts to come in, it mixes with the colostrum. During this mixing or transitional milk phase, you may feel your breasts getting larger and heavier as they fill up with breast milk. Many women experience breast engorgement during this time. It may be uncomfortable or even painful, but it should not last longer than a few days. Then, by the time you have been breastfeeding for approximately 2 or 3 weeks, your breast milk will have fully changed over to mature milk.

What Does Mature Breast Milk Look Like?

Mature breast milk is usually white, light yellow, or blue-tinged. Although, it can occasionally appear other colors depending on your diet and the colors of the foods that you eat. Blood from inside the milk ducts or from sore, cracked nipples can also make its way into your breast milk.

If that happens, your breast milk may look pink, brown, or have red streaks in it.

Mature milk may look thin and similar to skim milk, or it may appear creamier. Frozen breast milk often appears yellow and since it separates during freezing it may look layered, as well.

How Much Mature Milk Will You Make?

Once your breast milk has transitioned into mature milk and fully comes in, the amount that you make will adjust according to your breastfeeding habits and your baby's needs.

The more you breastfeed and pump your breast milk, the more mature milk you will make. You will also produce more mature milk if you're breastfeeding twins or tandem nursing. However, if you are combining breastfeeding and formula feeding (and you aren't pumping to keep up your milk supply), you will make less mature milk.

The amount of mature breast milk that you make also changes as your baby grows. When your baby is one-month-old, she may be taking 2 to 3 ounces of breast milk at each feeding. So, you will be making approximately 24 ounces of breast milk each day. This amount will go up as your baby gets bigger and takes more breast milk at each feeding. If you're breastfeeding exclusively, by the time your baby is 6 months old, will making between 36 and 48 ounces per day to meet his nutritional needs. Of course, this is just an estimate. Some women make less breast milk, and some women make much more.

What Is In Mature Breast Milk?

We actually do not know everything that's in breast milk.

However, scientists have so far identified over 200 different components that make up breast milk. Mature milk is full of nutrients such as carbohydrates, protein, fats, vitamins, and minerals. It contains everything your baby needs for healthy growth and development. It also contains health properties that support your baby's immune system and help protect him from illness and disease.

Does Mature Milk Continue To Change?

Once your breast milk reaches the stage of mature milk, it doesn't mean that it will stay constant from that point on. Mature breast milk continues to change for your baby.

Mature milk changes within the each feeding. At the beginning of a feeding, it starts out as a thin, watery, low-fat milk known as foremilk. Then, as the feeding goes on, it becomes creamier and higher in fat. This creamier milk is called hindmilk.

Mature breast milk changes throughout the day. The concentration of nutrients such as protein, fat, and lactose are different in the morning compared to the afternoon.

Mature breast milk changes as your baby grows. Not only does the amount of breast milk change as your baby grows, but the amounts of the nutrients and immune factors change, too. The makeup of your breast milk will be a little different when your baby is 1-month-old compared to when your baby is 6 months old or a year old. These changes don't mean that mature breast milk is no longer valuable to your baby after 6 months or one year. Yes, it changes. But, it is still nutritious and continues to provide many health benefits to older children.

How Long Does The Mature Milk Stage Last?

You will continue to make mature breast milk until you decide to stop breastfeeding, or you become pregnant.

After Weaning: Once your baby is fully weaned, or once you stop pumping for your child, the mature milk in your breasts will dry up and go away. However, it can take several weeks or even months until there is no longer any trace of breast milk left.

During A New Pregnancy: If you get pregnant while you're still breastfeeding another child, your mature milk will change as you get further into your new pregnancy. It will eventually turn back into colostrum for the new baby.

See Also: Answers To 7 Common Questions About Transitional Breast Milk 


American Academy of Pediatrics. New Mother’s Guide To Breastfeeding. Bantam Books. New York. 2011.

Lawrence, Ruth A., MD, Lawrence, Robert M., MD. Breastfeeding A Guide For The Medical Profession Seventh Edition.  Mosby. 2011.

Newman, Jack, MD, Pitman, Theresa. The Ultimate Breastfeeding Book of Answers. Three Rivers Press. New York. 2006.

Riordan, J., and Wambach, K. Breastfeeding and Human Lactation Fourth Edition. Jones and Bartlett Learning. 2014.

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