When does milk come in? Our expert guide to starting breastfeeding (2025)

There’s plenty to get your head around when it comes to breastfeeding. Whether you’re pregnant or in that newborn bubble, the way you feed your baby is likely to be something you think about a lot (as well as, ‘Will I ever get a decent night’s sleep again?’ Trust us, you will).

Breastfeeding is a journey, and everyone’s experience will be different. But knowledge is power, mamas, so we’ve spoken to three experts to help answer your questions about what to expect when your milk comes in – and what to do if it’s delayed.

When does breast milk start to be produced?

Earlier than you may think. Your body doesn't wait until the baby is here to start producing breast milk, as Louise Oliver explains:

‘Breast milk production typically begins during the second trimester of pregnancy — this is often referred to as the “first milk” and is called colostrum. Some mothers and parents may notice small drops of colostrum leaking from their breasts anytime from the 16th week of pregnancy onwards.’

The stages of breast milk production

Breast milk is amazing stuff and delivers exactly what your baby needs at any specific time. There are three different stages of breast milk production, each serving an important role:

Colostrum: The first milk

‘Colostrum is thick, often yellow in colour, and produced in small amounts,’ shares Oliver. ‘Although small in volume, colostrum is enough to sustain a newborn in the first few days until your milk supply increases. It’s packed with antibodies and vitamins and is designed to help protect your baby by supporting their immature immune system.’

Transitional milk

After three or four days, the colostrum will change into a thinner, white milk as your body transitions from producing colostrum to mature milk. This ‘in-between’ stage produces transitional milk, which has higher fat levels and lasts for around two weeks.

Mature milk

Typically, around ten to 15 days after birth, your body should start producing mature milk, which contains all the nutrients your baby needs and adapts over time as your baby grows.

‘Breast milk is produced on a “supply and demand” basis. When milk is removed from the breast through baby feeding, hormonal signals stimulate the production of more milk,’ explains Kate Brintworth. ‘This enables your body to regulate the amount of milk according to baby’s needs.’

If you’re ever worried your milk supply has dropped, speak to your health visitor or GP.

Signs that milk is coming in

One of the most obvious signs your milk is coming in is the size and feel of your breasts, as Brintworth explains: ‘When your milk is coming in, your breasts are likely to feel fuller and heavy, and may even feel a bit uncomfortable or leak.’

Another way to know your milk is coming in is to watch your baby for cues. ‘You might notice that your baby is gulping more during a feed and has milk around their mouth afterwards.’ says Brintworth. Also your baby’s poo will begin to change colour from the tarry black meconium to a brighter yellow colour, and nappies will feel heavier as they start to wee more often.

Brintworth adds: ‘When your milk first comes in, you may feel a bit like you are getting a cold. This should pass quickly, so if you [feel] more unwell or have headaches or a fever, contact your midwife or GP.’

When should I begin breastfeeding?

As soon as you can! Ideally, aim to breastfeed within the first hour after your baby’s birth. This is when babies are most alert, and it’s a hugely beneficial time for skin-to-skin bonding.

Managing early lactation

In the early days, the best thing you can do is relax and be kind to yourself.

‘Babies are born with the natural instinct to seek the breast, find it and latch on, so mums don’t really need to do anything,’ says Rachel Watson. ‘The best advice I can give is to relax and know that it may take a couple of weeks for you to feel like you know what you are doing, but it will get better.’

Watson adds, ‘Try and make sure the baby is deeply latched onto the breast, not just onto the nipple, as that will really hurt. All your baby needs to breastfeed for the first time is access to your body and time. Babies are not born starving hungry — they have been fed and nourished in the womb, so they don’t come out needing to eat, they come out needing to suck.’

How to prepare for breastfeeding

If you want to prepare for breastfeeding, the best thing you can do is be informed. You can sign up for various antenatal courses, from free NHS sessions to longer NCT courses.

Knowing the basics, like how to hold your baby and position them on the breast, as well as how to check if their latch is effective, will make all the difference. As Oliver explains, ‘Effective positioning and attachment can reduce the likelihood of experiencing pain when breastfeeding and supports your baby to easily access milk.’

You may also want to stock up on the essentials, like reusable breast pads and nipple balm.

What affects the timing of milk coming in?

‘After a baby is born, the birth of the placenta triggers the release of a hormone called prolactin, which supports milk production,’ says Oliver.

‘Prolactin is stimulated by skin-to-skin contact between the baby and mother or birthing person and effective breastfeeding or expressing. Where possible, at least an hour of uninterrupted skin-to-skin shortly after birth can encourage a baby to have their first feed and help to boost prolactin levels.’

Brintworth adds, ‘Sometimes, factors such as the amount of blood that you lost during the birth can have an impact on your milk coming in, especially if you lost a significant amount of blood. This can mean that it takes longer for your body to produce breast milk.’

Brintworth continues, ‘Your milk supply will build up gradually, to align with your baby’s needs. In the first few days, a baby’s stomach is very small — only about the size of a toy marble — and gradually gets bigger. If baby isn’t feeding effectively, this can mean that your body may get fewer hormone signals to stimulate milk production. Midwives will help you to help your baby [get] well latched on.’

What to do if your milk is delayed

Brintworth says, ‘The first thing that you should do is seek advice and support from an appropriately trained professional — they will need to assess you and your baby to make sure your baby is well and getting enough fluids.

‘Spending time in skin-to-skin contact with your baby in a calm, relaxed environment can also help encourage them to feed effectively and can help to stimulate your hormones for milk production.’

‘Milk may be delayed for a number of reasons, but except [in] a small number of cases, the milk will come, ’ says Watson. ‘You can help encourage your milk to come in with a bit of hand expression.’ If you’re unsure how to hand express, speak to your midwife or health visitor, who can talk you through it.

It’s important to look after yourself — eat well, drink plenty of water (breastfeeding brings on a thirst like no other!), get a comfy maternity bra and reach out for lactation support if you’re worried about low milk supply. Specific supplements for breastfeeding women, like these Breastfeeding Support Vitamins from Wild Nutrition, will help give your body a boost, too.

Conclusion

While starting breastfeeding may seem a little overwhelming, there’s plenty you can do to prepare yourself and a huge amount of support available if you need it. Follow our experts’ advice, try to relax and let your body do its job. And always reach out if you need professional reassurance or a helping hand.

If you’re after a day-by-day breakdown of what to expect over those first ten days, as well as how long to breastfeed, make sure you read our expert guide on what to expect when you start breastfeeding.

FAQs

When does milk come in after a C-section?

Breast milk may be delayed by a day or so because of a caesarean birth. Don’t worry — your colostrum will meet all your baby’s needs until your milk comes in. Lots of skin-to-skin time with your baby and frequent hand expressions will help bring in milk sooner.

Can I produce too much breast milk?

Yes, it’s possible. This is called an oversupply or hyperlactation and is when your body produces more milk than your baby needs. This differs from engorgement, which can happen when you’ve gone too long between feeds. If you have an oversupply, your breasts will feel engorged most of the time and will leak regularly, and your baby will struggle to maintain their latch, often ‘slipping off’ the nipple. If this lasts beyond six to eight weeks, consult a breastfeeding counsellor.

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