Prolactin: The Breastfeeding Hormone

The Hormone Responsible for Breast Milk Production

Mother breastfeeding newborn child.
When you breastfeed your baby, prolactin is released and it signals your breasts to make more breast milk. Camilla Sjodin/Johner Images/Getty Images

What Is Prolactin?

Prolactin is a hormone made in the pituitary gland of the brain. It is found in both men and women, and although it performs many functions in the human body, it is known as the breastfeeding hormone because of its role in lactation.

Prolactin and The Production of Breast Milk

Prolactin is the main hormone needed for the production of breast milk. During pregnancy, prolactin prepares your breasts to make breast milk.

However, the high levels of estrogen and progesterone produced by the placenta, prevent the prolactin from making a large amount of mature breast milk.

When you deliver your baby, and the placenta leaves your body, the estrogen and progesterone levels go down. The decrease in these two hormones lets the prolactin go up and signal the milk-making glands in your breasts to make breast milk. In the first few days after the birth of your baby, prolactin is responsible for the tremendous surge in breast milk that often causes breast engorgement as your colostrum changes over to transitional breast milk.

Prolactin and Breastfeeding

After your baby is born, the first rise in prolactin is what gets milk production started, but it's not enough to maintain the production of breast milk. To keep making breast milk, you need to breastfeed your baby or pump your breast milk.

When your baby breastfeeds, or you pump your breast milk, the nerves in your breasts send a signal to your brain to release the hormones oxytocin and prolactin.

The prolactin tells the milk glands in your breasts to make more breast milk, and the oxytocin is responsible for getting the breast milk from your breasts to your baby. As long as you continue to breastfeed (or pump) very often, your body will continue to release prolactin, and you will continue to make breast milk.

How to Raise Prolactin Levels to Make More Breast Milk

The best way to increase your prolactin levels is to breastfeed or pump very frequently. When your baby is born, you should be breastfeeding or pumping at least every 2 to 3 hours. The more often you stimulate your breasts, the more your brain will release prolactin. There are also certain herbs, foods, and medications that are used to increase prolactin levels.

However, it's important to point out that raising prolactin levels alone is not enough to create a healthy supply of breast milk. The stimulation of the breasts and the removal of the breast milk from the breasts is just as important.

Prolactin and The Decision NOT to Breastfeed

The levels of prolactin in your body are high during pregnancy and right after the birth of your baby. But since prolactin is released in response to stimulation at your breasts, if you do not breastfeed or pump your breast milk, the levels of prolactin will begin to go down. In the first few weeks postpartum, you will still produce breast milk and even experience breast engorgement. But, in the absence of breastfeeding or pumping, the production of breast milk will slow down and eventually stop.

Prolactin and The Return of Your Period

When you're breastfeeding, prolactin levels are high, and estrogen levels are low.

The relationship between these hormones keeps your breast milk supply up and your period away. If you breastfeed exclusively, it can delay the return of your period for many months. If you do not breastfeed, or choose to combine breastfeeding and formula feeding, the hormone levels change and you could see the return of your period as early as 6 weeks after the birth of your baby.

When your period does return, more estrogen and less prolactin can affect the production of breast milk. Sometimes, it's a just a dip in your supply during your period. But, it's possible that once your period returns, your breast milk supply will remain low.

Prolactin and The Lactational Amenorrhea Method of Birth Control

Exclusive breastfeeding is associated with high levels of prolactin. These high levels of prolactin prevent your ovaries from ovulating or releasing eggs. So, if you breastfeed exclusively for the first six months after the birth of your baby, it is unlikely that you will ovulate or become pregnant.

The lactational amenorrhea method of birth control (LAM) is based on high prolactin. If you breastfeed exclusively around the clock without giving your baby any supplements, your child is under 6 months old, and your period has not returned, then the chances of becoming pregnant again are very low. LAM is about 99% effective when followed correctly. However, once you are no longer breastfeeding exclusively, and your prolactin levels start to go down, your fertility may begin to return, along with the chances of becoming pregnant again.

Prolactin and Your Fertility

Prolactin can also interfere with your ability to become pregnant again when you're ready to try for another child. If you're still breastfeeding, or you've weaned your baby but you're still producing breast milk, your levels of prolactin may be high, especially if you have not yet seen the return of your period. So, if you're ready to get pregnant again, but you're having trouble conceiving, talk to your doctor.

Things That Can Interfere with Your Prolactin Levels

Supplementing: If you supplement your baby with formula or give your baby water between feedings, you aren't signaling your body to release prolactin.

Early Pacifier Use: The use of a pacifier in the early days and weeks of breastfeeding takes the place of the some of the breast stimulation that you would be getting if you put your baby to the breast instead. The more you put the baby to the breast, the more prolactin is produced. When your child uses a pacifier, it's a lost opportunity to increase prolactin and support a healthy supply of breast milk.

Birth Control That Contains Estrogen: When there's a change in the balance of estrogen and prolactin, it can affect the breast milk supply. Birth control that contains estrogen is known to cause a decrease in milk production.

Breast Surgery: Breast surgery performed near the areola or the nipple can cause damage to the nerves that signal the brain to release prolactin.

Numbing Creams: A numbing cream should never be used to treat sore nipples. Not only can it numb the baby's mouth, but it can numb the nerves in the breast, as well. If the nerves cannot send a signal to the brain, prolactin will not be released.

Smoking: Smoking causes a decrease in the levels of prolactin.

Depression: Prolactin levels are lower in mothers who suffer from depression.  

 

Sources:

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

Cadwell, Karin, Turner-Maffei, Cynthia, O'Connor, Barbara, Cadwell Blair, Anna, Arnold, Lois D.W., and Blair Elyse M. Maternal and Infant Assessment for Breastfeeding and Human Lactation A Guide for the Practitioner Second Edition. Jones and Bartlett Publishers. 2006.

Lawrence, Ruth A., MD, Lawrence, Robert M., MD. Breastfeeding A Guide For The Medical Profession Eighth Edition. Elsevier Health Sciences. 2015.

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

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