Prolactin: The Milk Maker
Last week we talked about the love hormone, oxytocin. Although, oxytocin is so commonly talked about when discussing breastfeeding, we also learned that oxytocin does not actually “make milk”. Prolactin is the real milk making hormone! Although other hormones, like oxytocin, are necessary in order to produce milk, prolactin is responsible for some breast tissue development and the production of milk. (2)
Before jumping too far into prolactin discussion, it is important to discuss Lactogenesis and the varying stages that accompany it. Lactogenesis I occurs during pregnancy and ends once our placenta is removed/delivered. As the placenta is removed, our bodies quickly transition from progesterone heavy to prolactin heavy, which initiates the onset of Lactogenesis II. During Lactogenesis II, our bodies are producing milk on an endocrine system with the excretion of prolactin. (1)
Our bodies are signaled to excrete prolactin as baby is brought to breast or we stimulate our breast with a breast pump. Similar to oxytocin, prolactin is released as our breast are stimulated and a signal is pushed to our hypothalamus. The hypothalamus in response releases prolactin through the anterior pituitary gland. This increased level of prolactin, increases the production of milk. (2)
As our bodies transition from Lactogenesis II to Lactogenesis III, our bodies transition from an endocrine secretion to exocrine secretion. This is important to know, because as this transition occurs prolactin levels do not remain elevated. It is critical that mothers continue to bring baby to breast or pump in order to maintain high levels of prolactin and to continue to make milk. (2)
In fact, our prolactin levels will even vary throughout the day. It is found that prolactin levels actually follow a circadian rhythm. There are many theories on why our bodies were made this way, but regardless of why, it is true. With that said, prolactin levels in breastfeeding mothers tends to be highest between 2-6AM and then the levels drop to the lowest levels in the late afternoon/early evening. Because of this increase in prolactin in the early hours of the morning is why mothers are strongly encouraged to continue removing milk throughout the night until baby is at least 6+ weeks old. (3)
For if we do not remove milk in the middle of the night, our prolactin levels will continue to drop. Our levels will drop as an absolute too, which means our prolactin levels will not be as high in the middle of the night and they will be even lower in the afternoon. An overall drop in prolactin, also suggests an overall drop in milk production. This overall lower prolactin level is suggested in Figure 1.
Figure 1: Theoretical Prolactin Levels Versus 24 Hours Without Increases at Each feeding
The solid line suggests prolactin levels in a mother #A, who is removing milk via nursing or pumping throughout the entire 24 hours of the day. However, the dotted line suggests prolactin levels in a mother #B, who is only removing milk throughout the 12 hours of the day. If everything else is equal, we can assume that mother #B will experience lower levels of milk production than mother #A.
When we decide to miss feedings or pump sessions throughout the night, we also are missing opportunities in spiking our prolactin levels. As we discussed “how” prolactin is released, we understand that every time mother expresses milk that she will experience an increase in prolactin in her blood stream. So in reality, prolactin levels in a breastfeeding mom will look like Figure 2 throughout the day. However, whenever we miss an opportunity to remove milk, our
Figure 2: Theoretical Prolactin Levels Versus 24 Hours With Increases at Each feeding
prolactin levels do not experience that boost and continue to fall further. Mother A is removing milk throughout the entire 24 hours, which increases her overall prolactin levels, as well as, provides opportunities for prolactin to increase - this also helps maintain higher levels of prolactin.
I like to think of our breast as almost a drive thru. Baby drives up to menu board and places an order. The hypothalamus takes the order and says “baby wants some milk”. The chef does not just “have” milk, he has to put it together. So he grabs some oxytocin and prolactin and pushes it down the line. As the baby drives up to the window, they are able to give him some fresh milk. HOWEVER, if baby or our pump does not place that order, the chef does not do anything. The chef will only make milk for the orders that are placed.
Another important caveat, once we understand how our milk is made, it can be easily understood that in order to make milk, we have to move milk. There are a lot of products on the market, which may or may not increase your milk supply. However, do not invest in these without either increasing the amount of times you remove milk from your breast or utilize them as an “in addition” to removing milk. No matter how many cookies, sports drinks, or galactagogues we eat, our bodies cannot maintain or increase milk supply without the release of prolactin.
Struggling with your milk supply? Do not hesitate to schedule a consultation with me - I would love to help your get to a root cause!
Love,
Antoinette C., CLC
Lauwers, J., & Swisher, A. (2020). Counseling the nursing mother: A Lactation Consultant’s Guide. Jones & Bartlett Learning.
Professional, C. C. M. (2024, August 21). Prolactin. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22429-prolactin
Wendy. (n.d.). Prolactin and the importance of nighttime nursing or pumping. Motherlove Herbal Company. https://www.motherlove.com/blogs/all/prolactin-and-the-importance-of-nighttime-nursing-or-pumping?srsltid=AfmBOorBMP-9H3z7pdYsq3l5TaZdEsIJQW2Szwlzuzhf2CZDmGAmvGB6