Making Milk
Ever wonder how we make milk for our babies?
Lactation is part of mammal reproduction. All species of mammals make milk for their babies which completes the infant’s development postpartum. Mammals are born immature--not yet fully formed--and it is our milk that puts the finishing touches on the growth of their systems. After birth, our milk takes over from the umbilical cord, providing life support for baby mammals: nourishment, hydration, growth, immunities, hormones, and complex communication between their body and our own.
So how do mammals actually create the milk?
The Mechanics of Making Milk
We synthesize milk in glands that are like specialized sweat glands. We make milk as needed, based on how much is extracted. The more the milk ducts are emptied, the more milk they make.
We actually manufacture milk while baby is nursing, rather than in between feeds. If you were picturing that our breasts were empty vessels that would passively refill between nursing sessions, it is almost the exact opposite. We do have some very limited storage capacity in our breasts, or rather in the ducts in our breasts (since the breasts themselves are not vessels--they are made of glandular tissue), but we don’t store large quantities therein. Instead, when babies latch on, they prime the ducts to trigger a ‘letdown’, which is when the milk starts flowing. They suckle with intention, and their jaw movements cause our milk to flow. We actively manufacture the milk during this process--while baby is actually feeding.
When that particular letdown, or feed, is over, usually baby will fall into a contented, milk-drunk sleep, satisfied and full. The vast majority of nursing sessions are single sided--one breast only. Next time, we can offer the other breast, with the vague intention of alternating each side per feed. One feed = one breast. Next feed = the other breast.
If baby is ravenous and keeps suckling after the letdown is all done and the breast has been ‘emptied’, they will simply trigger another letdown. Another full meal is now available. If you switched to a new baby after each feed, your amazing milk-ducts would just keep producing more and more milk in response to each one’s suckling. We never run out. We never need to wait. Making milk is like making sweat--we do it as needed, and there is no upper limit.
Every time the breast is ‘emptied’, our body is prompted to increase milk production. So if we suddenly need to make more milk than before, whether it’s because our baby went through a major growth spurt, or because we adopted a new set of twins to raise alongside our singleton, the way to ramp up our milk supply is to breastfeed more. More nursing leads to more milk. Aim to “empty” the breasts as much as possible, as often as possible. Note that they’re never truly “empty”--they can make unlimited quantities of milk--but the more you allow baby/babies nurse, the more milk your body will know to make. More = more.
It’s like a small business’s inventory. If you make sandwiches in a food truck, you will be in the habit of making as many as you usually sell. But if business increases, you will start making more in response to the new demand. Your food truck (like our milk ducts) will even start anticipating selling more, and will prep more sandwiches in advance, so that they are pre-made and on display at lunch time. The crowds will never go without sandwiches: when the demand first increases, we will be making them as they are ordered, because we didn’t anticipate the new popularity. But on the second or third day, we will be prepared, and we will have extra sandwiches ready to go.
Same for our milk glands. We will always make milk as needed, while it is being extracted, like sandwiches made-to-order, but if the demand rises, so will our body’s anticipation. So a single letdown might have more volume after a couple days of baby prompting multiple letdowns at every sitting. Every letdown is like a single sandwich. When our regular customer starts habitually ordering a second sandwich at every visit, it might take 2 or 3 visits before we assume that’s what they’ll want every time. Same with if that customer starts showing up with a friend, or a crowd. Our food truck has no limits.
If you think you’re not making enough milk for your baby, the solution is usually simply to feed baby more. Barring an underlying medical condition, this basic adherence to the lactation law of supply & demand will increase the amount of milk you produce.
The Hormones of Making Milk
Another factor of milk production is the hormones. There are many hormones involved in lactation, including estrogen, but two of the main ones are prolactin (for milk production) and oxytocin (for milk generation).
Prolactin in the mother’s or lactating parent’s blood increases when the baby suckles. This causes milk production, based on how much suckling occured. Prolactin levels peak after the feed is over. Therefore, each nursing session impacts milk production in anticipation of the next one. When baby nurses, it communicates how much was needed in order to plan ahead. Prolactin’s main effect is to make more milk for the subsequent feed. The more suckling and nursing that occurs, the more prolactin is produced. This is especially important during the first several weeks when lactation is being established, which is one of the reasons bottles and supplements are discouraged for the first six weeks.
More prolactin is produced at night than during the day. When baby night-nurses, this causes prolactin levels to peak and optimize milk production. This is one of the reasons it is important to nurse day and night, since the nighttime feedings have the most impact on our milk production. This is also why trying to eliminate or discourage night wakings too soon can result in milk supply problems.
Like many hormones, prolactin also affects our state of mind: when we produce it, it makes us feel calm and drowsy, serene and sleepy. Night nursing can actually help us get rest, especially if we’re bed-sharing or have our baby close by.
Oxytocin is the hormone that causes milk flow, also known as the milk ejection reflex, or letdown. Oxytocin is produced more quickly than prolactin, and allows the baby to summon the milk created by the prolactin. When baby begins to suckle, oxytocin surges, which causes the milk to flow towards the baby.
We also produce oxytocin whenever we cuddle or look at our baby, especially with skin-to-skin contact. Oxytocin causes us to feel calm and dreamy, loving, caring, and affectionate. It triggers our parenting instincts such as empathy and nurturing. It makes us feel like the world is a good place. It is often called the love hormone.
Another important feature of oxytocin is that it affects everyone nearby. When we are emanating oxytocin, our baby gets infused with loving, calm feelings, and so does our partner, or anyone else in close proximity. Oxytocin has the benefit of making everyone around the baby feel nurturing and patient, loving and caring. This activates parenting instincts in partners, and also in anyone else in the household. It’s the same hormone you can buy to calm your cat, since all mammals project some version of oxytocin during lactation, which has a calming effect on nearby mammals. This decreases the risk of aggressive behaviour from predators, or even members of the same species (male cats towards kittens, for example). When lactating, we create an oxytocin bubble of warm, fuzzy feelings that creates bonding between ourselves and our baby, and anyone else present.
Both of these breastfeeding hormones play another important role, in that they are protective against postpartum depression and anxiety. Breastfeeding hormones all have a mood-stabilizing function, reducing stress, and helping us feel calm and content, which is clearly beneficial during such a potentially stressful life transition. However, while breastfeeding itself is prophylactic against postpartum effects, trying but being unable to breastfeed can be an increased risk factor. Struggling with breastfeeding, especially in the early weeks, can aggravate feelings of postpartum anxiety, and can make matters worse. This is why support--easy, available, affordable, and most of all competent support--is so important for new parents to be able to access.
Sometimes milk production seems low because our oxytocin and/or prolactin levels are low. The solution in each case is the same: nurse baby more. Every time you breastfeed, the prolactin receptors gear up for the next feed. Feeding more frequently, causes us to synthesize more milk. Likewise, we need high levels of oxytocin to generate milk flow, and the most straightforward way to produce oxytocin is to breastfeed. Cuddling baby, skin-to-skin contact, holding, and playing all encourage oxytocin as well, but breastfeeding is a bigger trigger. More nursing = more milk.
Troubleshooting about Making Milk
If you feel like your milk supply is inadequate for your baby, there are several likely causes.
Usually, the answer is simply that you’re not giving baby enough access. If you’re trying to limit baby to any kind of schedule, or you’re trying to impose any kind of time restrictions on baby’s feeding, you are probably sabotaging your milk supply. We have to nurse on demand (on cue, baby-led), or else baby cannot communicate effectively with our milk-glands. Baby has to be able to nurse as often as baby wants, in order to harmonize our milk production to their needs. Limiting baby’s access prevents this. So if you’ve been told to only feed every three hours, or to avoid feeding before a nap, or to time your feeds, or anything that relies on a clock instead of on baby’s cues, consider stopping. Listen to baby instead. It is baby, and no one else, who has to regulate the amount of milk we make. They need unrestricted access to do this.
One common form of limiting baby’s access is attempting to sleep train prior to six months old. The hormone chiefly responsible for milk production--prolactin--is more responsive at night. So night nursing is actually very important for maintaining milk production, but even more so for increasing milk production as baby grows. As mentioned earlier, one of prolactin’s functions is to estimate how much milk to make for the next feed, based on how much is being extracted now. Night nursing sessions are instrumental in boosting your milk production whenever baby goes through a growth spurt. Preventing or limiting night nursing can accidentally undermine your baby’s efforts to augment your milk supply.
Similarly, if you are using substitutes, such as pacifiers or bottles, this can also sabotage your milk supply, especially in the first three months. Every time a baby suckles, they are expecting the action to communicate with your milk glands and prolactin receptors. And every time baby suckles on something other than the real breast, your body is missing vital communications about how much milk to make, what kind, and when. If you have concerns about your milk supply, ditch the pacifier right away. It is a very common culprit for low milk production.
Sometimes the cause of low milk supply isn’t insufficient access, but insufficient milk transfer, even though baby is at the breast! This is usually caused by a poor latch, which is usually caused by a poor position. Baby can most easily get a good latch when their whole body is facing you (tummy to mummy) and they are slightly above your body, draped over you. Gravity should be pulling you together, rather than apart. This is called the laid-back position, and it is an excellent starting position that encourages comfort for you, while allowing baby to use all of their reflexes and instincts to achieve a perfect position and latch. Once the latch is perfect (a couple to several weeks), you can sit as upright as you like. How do you know it’s a good latch? It feels comfortable, baby swallows effectively, baby has bowel movements, and baby is contented and ‘milk drunk’ after each feed.
A lot of people think a pump is the clear solution to supply problems, but it can actually be the cause! Baby can extract much more milk--can drain the breast--in a way a pump never can. A pump is blunt and ineffective compared to baby’s superior breastfeeding proficiency. And, a pump will never stimulate your oxytocin release. This is only accomplished by holding your actual baby at the breast. A pump can be a useful--even vital--intervention if you are separated from your baby, or if your baby can’t latch, but is generally a poor substitute for baby at the breast. Your baby can summon infinite milk from your glands--fountains and gallons and cornucopias--whereas a pump can only skim the surface. Exclusive pumping is possible, but it takes a huge amount of time and effort to avoid the decline towards dwindling milk production.
Another milk-supply saboteur can be hormonal methods of birth control. The pill, for example, usually contains progesterone. This hormone suppresses ovulation, but also suppresses prolactin. You can’t make milk without prolactin. If you are on a hormonal method of birth control, and you notice your milk supply is affected, talk to your doctor or midwife. You might need to switch methods until your baby weans.
The cure for low milk supply is rarely special foods, teas, or medications. None of these things make much difference (nor do they do harm--so feel free). But the absolute best cure for milk supply issues (in the absence of a medical condition), is The 24-Hour Cure, sometimes called The 24-Hour Breast Buffet. This is where you spend 24 hours cuddling in bed with your baby, skin to skin. You don’t leave the room (except to use the washroom). Someone else brings you food. And you just breastfeed, cuddle, and sleep for 24 hours. You can watch TV and read, but don’t get out of bed. Breastfeed as much as you can, as much as your baby will tolerate. By the end, you will have more milk than you know what to do with. This approach uses the mechanics of milk production, and maximizes the hormones of milk ejection, and results in formidable success.
Teas, herbs, special foods, medications, cookies...these aids are all mostly harmless and might give your milk or your confidence a nominal boost, but there is no substitute for the lactation laws of supply and demand, and the hormonal feedback loop. If your baby does not have adequate opportunities to extract milk, or if you are limiting your baby’s ability to communicate their needs to your milk glands, there is no herb that will work instead.
How do we make more milk? It may seem like a paradox, but we make more milk by making more milk. When it comes to mammal lactation, more really is more.
Stephanie Ondrack lives with one partner, four kids, three chickens, and five cats in East Vancouver. Stephanie has been in the birth profession for almost 20 years, and still thinks lactation is pretty darn cool.