The Magical Hormones of Lactation
- Molly Veltz
- Jul 17, 2024
- 4 min read
Updated: Jan 7
Hormones play a major role in getting you pregnant, and keeping you pregnant, so it should be no surprise that they drive lactation!
Have you noticed that feeling of sleepiness and relaxation that washes over you when your baby gets into a rhythm of sucking at the breast? Do you ever experience a wave of emotion, an overwhelming love for your baby while he breastfeeds? If so, it's not just a coincidence, it's Oxytocin and Prolactin at work! During the postpartum period, these two hormones work in conjunction with each other to make lactation happen. Prolactin tells the breasts to make milk, and oxytocin turns on the faucet so the milk will flow. They are also called the "mothering hormone" and the "love hormone," because they promote bonding. Both are released by your brain when nipple fibers are stretched inside your baby's mouth, or by a pump. That stretch sends a signal that elicits a flood of prolactin and oxytocin, which then open your "Breastaurant"for business. Oxytocin release comes in pulses, and prolactin rises more slowly and steadily. Let's take a closer look at what exactly is happening.
Oxytocin causes muscle contractions. If you delivered in a hospital, then you might have have Pitocin during your labor to increase the strength and frequency of uterine contractions. Pitocin is the synthetic form of oxytocin. You may have also had a bolus of "Pit" pushed into your IV after your baby was born, whether vaginally or by C-section. This causes your now empty uterus to clamp down and stay contracted, so that it will stop receiving a heavy blood supply. It doesn't need a high blood volume once it has ejected its passenger. And if it stays relaxed and continues to command a generous blood flow, you can develop excessive bleeding or a postpartum hemorrhage. A great way to naturally help your uterus make this transition after delivery, is to put your baby to breast. Once baby starts sucking, the oxytocin that is released is soaked up by the uterus, and helps it shrink and stay firm, like a clenched fist. Within your breast, the oxytocin causes the grape-like clusters of milk sacs to contract, causing a "milk ejection." During the colostrum phase, this milk ejection is more like a soft, slow, drip-drip from a leaky sink. Once your milk comes in however, the milk ejection reflex can be like a fire hose!
As your supply gets established, the oxytocin release can cause a “let-down sensation” that many moms describe as a tingly or prickly feeling in one or both of their nipples. However, it is important to note that many first time moms can’t feel their let-down sensation for many weeks, or even months. Some new moms become anxious when they don't immediately feel the let-down sensation, and worry unnecessarily that there may be a problem with milk flow or supply. Moms should be reassured that their hormones are in fact circulating if they notice their eyelids getting heavy during the feeding, or if they notice their uterus cramping. These effects can be stimulated by a breast pump as well. In fact, studies have demonstrated a rise in oxytocin levels just by relaxing with your baby skin to skin, as well as with gentle breast massage. Even hearing your baby cry, can often trigger an oxytocin release.
Prolactin is the milk-making hormone. Together with a good blood flow to your breasts, prolactin synthesizes milk. Fun Fact: your breasts are not just milk storage facilities. When your baby nurses and drains your breasts, he gets some milk that was sitting there waiting for him, and toward the end of the feeding, milk that is being made to order! Thus, it is said that the lactating breast is never fully empty. It can always produce more milk in response to a demand. Prolactin levels begin rising during a feeding and become significant at about 10" in, and can stay elevated even after the feeding has ended, for an hour. Double nipple stimulation from a pump or tandem-nursing twins, results in higher levels of prolactin and greater milk yield. Some parents who find their milk supply low, make efforts to increase their prolactin levels by taking galactgogues, which are drugs/supplements that have the side effect of increasing serum prolactin. Reglan, Metformin, Domperidone, and Fenugreek are just a few examples. Contraindications do exist, so only try galactogogues under the supervision of your OB, or lactation consultant. The best way to make more milk, is to empty your breasts more frequently.
So besides helping you make and deliver milk, what can the hormones of lactation do for you? There are many benefits that we derive from having these hormones circulating 24/7. Oxytocin lowers blood pressure and the stress hormone cortisol; it also enhance digestion. In studies, breastfeeding moms demonstrate less anxiety, a decreased sensitivity to stress, and lower rates of postpartum depression, when compared with formula-feeding moms. Breastfeeding moms also demonstrated increased social interaction, and more attentiveness to their babies, than formula-feeding moms. Of course, formula feeding moms can also be happy, have coping mechanisms, and feel extremely attached to their babies. But breastfeeding moms have a hormonal inclination toward these traits, which is a huge benefit, given the stress of parenting.
Another advantage that breastfeeding moms enjoy is the sleepiness that oxytocin induces, making it a breeze to fall back asleep after that 3 a.m. feeding, and easier to take a nap while baby sleeps in the middle of the day. Although it seems counterintuitive, given the demands of breastfeeding, lactating moms may experience a higher quality of sleep, and enjoy more total sleep, than formula-feeding moms. One study indicated that exclusively breastfeeding moms enjoy the strongest benefit of all when it comes to quantity and quality of sleep. This is great news for the exhausted postpartum mom - she is hormonally primed to be sleepy after baby has fed and is himself, quite sleepy. Synchronizing sleep is a critical survival skill for new parents to master!
So put all that on your radar! And enjoy what your hormones are doing for you while you lactate. Understanding the processes at work can help you make sense of this new superpower that you're beginning to command.
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