Your "Letdown" And Why It Matters

Milk production is more than ‘emptying’ the breast

Making breast milk is a simple process that happens automatically: the more milk is removed from the breast, either by the baby sucking or by expressing, the more milk your body is signalled to make. However, this is only only half of the equation. Your baby can’t get his milk all by himself and even the best breast pump can’t empty your breasts effectively by suction alone. Releasing your breast milk is the other half of the milk production process and your milk ejection reflex is the key to this.

As your baby starts sucking, or you begin to pump milk, the milk that has collected in the large ducts or milk sinuses directly behind the nipple will be removed. Milk in the smaller ducts and alveoli, higher in the breast can’t be withdrawn by suction alone but needs to be delivered by actions within the breast. This milk is released to your baby by the ‘letdown’ or ‘milk ejection reflex.’

How does the letdown reflex work?

Imagine the inside of your breast looking like a bunch of broccoli – with your nipple on the end of the stalk and the florets being the cells inside your breast. Higher up in your breasts, there are milk secreting lobes (the clumps of broccoli florets). As your baby starts to suck, the stimulation of the nerves in your nipple trigger the release of the hormone oxytocin. This causes cells around the milk secreting alveoli (the tiny buds of broccoli) to contract and duct passages (stems of each broccoli floret) to widen, pushing milk down into the sinuses behind the nipple. This is your ‘letdown’ or ‘milk ejection reflex’ at work.

Your baby’s latch and sucking draws your nipple into his mouth, stretching it up to the junction of the hard and soft palate, keeping it in place as he feeds. Then, by compressing the areola with his tongue and jaw, the baby presses the milk into his mouth, coordinating sucking, swallowing and breathing to receive a good flow of milk.

Fore milk and hind milk

Not only will your baby receive a good flow of milk as your milk lets down but this reflex will be squeezing the higher fat milk that adheres to the sides of the alveoli down to your baby too. This higher fat milk is often called ‘hind milk,’ while the first milk your baby drinks is referred to as foremilk. It doesn’t mean there are two types of milk: consider how, when you have a cold tap running and you turn on the hot tap, the water gradually mixes from cool to warm. This is a similar process as the higher fat milk is made available to your baby. However, to get the ‘best’ milk it’s important to let your baby feed until he signals he is ready to come off the breast. By timing feeds or restricting feeds to an arbitrary number of minutes each side, you can deprive your baby of important nutrition and the fattier milk. You can trust your baby to take exactly the amount of milk he needs in the consistency that he needs for growth and development. For instance, on a hot day, your baby may have frequent shorter feeds to quench his thirst (he doesn’t need water), at other times he may have a longer feed to satisfy hunger.

Signs of a healthy let-down reflex

You may feel your letdown reflex as a strong sensation of pins and needles or you may not feel it at all. However, a few simple signs can show you it’s working just fine: in the first week after birth, you may feel uterine cramps as you feed your baby; you will see your baby’s suck change from short uneven sucks at the beginning of a feed to longer, more rhythmic sucking a minute or so into the feed or your baby may start swallowing quickly to manage the initial faster flow; you may feel relaxed or drowsy (this is the effect of oxytocin release); and/or you may feel super thirsty due to a reflexive flow of fluid from your bloodstream as the milk ejection occurs.

Conditioning your letdown reflex

Your letdown reflex can be inhibited by stress and exhaustion or emotions such as embarrassment if you are in an uncomfortable environment and it can become slower as your baby grows and feeds less too. Some older babies get impatient as they wait for the faster milk flow and will pat you on the breast or ‘tweak’ the other side to try and elicit a letdown.

The good news is, you can condition (or train) your body to release milk and once breastfeeding is established, even a serious emotional shock won’t affect your milk flow. To condition your letdown, it can be helpful to choose a ‘stimulus’ or a routine around beginning to breastfeed to signal your body to release milk. For instance, you may have a drink of water, take some deep slow breaths and imagine milk flowing over a waterfall or, if you are pumping and separated from your baby, you could smell your baby’s clothing. If you follow your routine consistently, your letdown will naturally become stronger and more reliable whatever the environment or circumstances.

You can also stimulate milk flow by using breast compressions – with your thumb on one side of your breast and four fingers on the opposite side, the action is press, compress (hold for a few seconds) then release. Do this higher up on the breast, not close to the nipple. You will see your baby start to suck faster or, if you are pumping and flow has slowed, you will see milk start dripping again.

When letdown hurts

Your letdown can be painful at first but this usually settles as your breasts adapt to breastfeeding. However, there can be conditions that contribute to a painful letdown such as a baby with a poor latch or an oversupply of milk which can be accompanied by a forceful letdown, making your baby splutter and cough. You can gently break the suction and remove your baby from the breast, letting the milk flow into a towel or catch it in a cup, until the flow slows.   Other reasons could be nipple thrush, or engorgement . If you have concerns it’s always best to check with an IBCLC lactation consultant who can take a history, observe a feed and offer personalized help.