The let-down reflex

The anatomy of your breasts 

There are several ducts on the inside of your nipples which branch out into your breasts; at the end of the ducts are a multitude of alveoli containing milk producing cells. These cells take nutrients from your blood and turn them into milk. The milk ducts then transport milk to the tip of your nipples, where milk is released from several openings called milk duct orifices. This network of ducts looks similar to a tree, with the trunk being the nipple, the branches the milk ducts and the leaves the alveoli.

Oxytocin and Prolactin

The two main hormones involved in milk production are oxytocin and prolactin. Oxytocin, often called the hormone of love, causes the contractions of orgasm, birth and lactation. It promotes feelings of love, bonding, calm and well-being in both you and your baby. Prolactin is the hormone that creates milk; it induces calmness and mothering behaviours. Prolactin levels are highest in your body between 2am and 4am, which is why mothers often notice they produce more milk at night, and why breastfeeding (or pumping) at night in the early months is so crucial to establishing and maintaining your milk supply.

The let-down reflex

When your baby suckles at your breasts, your brain releases oxytocin, which travels in your blood down to your breasts, where it makes the muscles surrounding the milk producing cells contract and push the milk out. This process is called the milk ejection reflex, or the let-down reflex, as milk is ‘let-down’ from the breasts. The removal of milk from your breasts – by your baby or by pumping - then tells your body to make more prolactin. Milk production is reliant on supply and demand: the more often your baby feeds (or the more often you pump), and the more milk is removed, the more milk you will make.

The Feedback Inhibitor of Lactation (FIL) and the importance of frequent milk removal

 Whenever your breasts get hard and full, a protein known as the Feedback Inhibitor of Lactation, builds up in your breasts, telling them to stop making milk. This means milk production slows down when your breasts are fuller and speeds up when your breasts are softer. This is why regular milk removal is so important for maintaining a good milk supply. A baby will typically breastfeed at least 8-12 times in 24 hours; in fact, many babies will breastfeed more than 12 times in 24 hours. A mother who is exclusively pumping should aim to pump at least 8 times in 24 hours because regular milk removal helps promote good milk production and protect her milk supply. If milk is not removed very regularly either by breastfeeding or pumping, a mother's breasts will get the message to gradually produce less and less milk.

What does the let-down reflex feel like?

Some women don’t feel the let-down reflex at all, others feel a tingling or tightening sensation in their breasts, or a sudden feeling of fullness, and a few women actually find the let-down reflex quite uncomfortable or even painful. Women usually experience two let-downs during a feed, but many are only aware of the first one. This tends to occur after the baby has been suckling for a minute or two. If you are one of those mothers who don’t feel their let-down, the way you’ll know it’s happening is that you will see, and possibly hear, your baby swallowing faster, and you may notice milk dripping from your other breast.

Uterine contractions

In the first week or so of your baby’s life, you will often feel uterine contractions at the same time as the let-down reflex. This is because the oxytocin causing the muscles around your milk producing cells to contract also causes your uterus to contract back down to its pre-pregnancy size. This is one of the beneficial effects of breastfeeding: your uterus shrinks back down faster. These contractions can feel quite painful, especially with second and subsequent babies, and some women choose to take paracetamol to help with the pain. Paracetamol is compatible with breastfeeding. Breathing in through your nose and blowing long breaths out through your mouth, as during birth contractions, can also work well.

Oxytocin – the ‘shy’ hormone

When you’re breastfeeding your baby, having a let-down reflex is rarely something you need to think about, as your baby’s presence is all your brain needs to release oxytocin, but when mothers are pumping, and especially if they’re doing so when away from their baby, or when they are anxious about their milk production, or indeed feeling worried about anything else, it can be harder to get the milk flowing.

Oxytocin is linked to loving feelings, and although a mother might like her pump and be pleased to have it, few women actually love their pump. In addition, oxytocin is often called the ‘shy’ hormone, as it’s harder to get a release of oxytocin if you aren’t feeling safe, calm and unobserved. Imagine being told you needed to have an orgasm within a set amount of time, especially if you weren’t in the mood. It would be even harder if someone you didn’t feel comfortable with were sitting there watching you!

Once mothers are used to pumping, and especially when mums are pumping at the same time, or times, every day, their breasts become accustomed to the process and having a let-down isn’t usually a problem, but if you are new to pumping, there are some steps you can take to help with the process.

How to encourage the let-down reflex

• Warmth and massage

 Firstly, apply warmth to your breasts - pouring comfortably hot water into a clean nappy makes a great warm compress – and then gently massage or stroke your breasts. It’s even better if someone you feel comfortable with can rub your shoulders and/or feet. If your baby isn’t in front of you, have a photo of him or her to look at, and a piece of clothing or muslin that smells of them to sniff.

• Try to relax

 Try to relax as much as possible, for example by listening to music you enjoy, or some hypnobirthing tapes. Some mothers find practising mindfulness or imagining their favourite place really helpful. Watching a TV programme that puts you in a good mood can work wonders. One mother who had to do a lot of double pumping at the beginning of her breastfeeding journey, used to watch an episode of Friends during each of her pumping sessions.

• Pain prevents oxytocin release

Please remember that pain impedes the release of oxytocin, so it’s essential that your breast shields fit comfortably, and that the vacuum on your pump isn’t set too high. Start with the vacuum low and the cycles high, then once the milk starts to flow, turn the cycles half way down, and the vacuum up so that the suction is firm but totally comfortable. If you put the vacuum up too high, you’ll produce less milk and you might also cause nipple damage.

• Try not to stare at the pump sets

Rather than sitting and staring at the pump sets, some mothers choose to cover the pump sets with baby socks, so that they can’t see how much milk is coming, and therefore don’t obsess about whether or not they’re producing enough milk.

• Pumping bra

When double pumping, it’s recommended to either buy or make yourself a pumping bra that will hold the pump sets in place. You can customise an old exercise bra you don’t mind sacrificing, by cutting holes in it where the pump sets need to go. Make sure the bra is comfortable and doesn’t dig in anywhere or push the pump sets too tightly into your breasts as this can cause blocked ducts. A pumping bra will also allow you to massage and compress your breasts while you pump. This is known as hands-on pumping and it helps both with the let-down reflex and also in removing more milk from your breasts.

Oxytocin is triggered in many ways

• By having your baby in skin to skin

• By seeing, hearing and smelling your baby

• Sometimes by hearing someone else’s baby

• By thinking of your baby

• By breastfeeding

• By pumping

Some women even experience a let-down when witnessing a kind act, such as seeing someone help an elderly person cross the road, or when seeing something they find adorable, such as a video of puppies playing.

Things that help oxytocin to flow

• Feeling warm

• Feeling calm, safe and relaxed

• Not feeling observed

• Not feeling pressured or anxious

• Not being in pain

• Gently stroking or massaging your breasts and nipples

• Having your shoulders and/or feet massaged

• Seeing a photo of your baby

• Practising mindfulness

• Listening to a hypnobirthing tape

• Listening to music you enjoy

• Watching a TV programme or film that is fun and light-hearted

Imprinting on your pump 

One last thing to point out, is that when a mother has become used to a particular brand of pump, it can sometimes be hard for her to get a let-down reflex for a different brand. It’s as if her brain has imprinted on that brand and she’s bonded with it. In fact, if a mother has been exclusively pumping for a while, and has been separated from her baby while pumping, sometimes she might need to think about her pump to get a let-down when she starts breastfeeding her baby. This is another reason why it’s a good idea to look at a photo of your baby while pumping, rather than staring at your pump. If you would like, or need, to change the brand of pump you’re using, it can help to spend a week alternating between the two types of pumps so that your brain learns to accept the new brand.