What causes low milk supply – and is there anything I can do about it?

low milk supply
What causes low milk supply?Maki Nakamura - Getty Images

Establishing a good milk supply – and feeling confident that you've done so – is often one of the biggest challenges experienced by people who are new to breastfeeding. Part of the problem is that it is virtually impossible to measure how much milk you are producing and how much your baby is consuming.

That could be an issue anytime. But in a culture of tracking everything from sleep quality to menstrual cycles, trusting your body to know how to feed your baby with no data to affirm you're doing it 'right' can feel like a huge leap of faith – especially for first-time parents.

Besides, as you might have experienced, expectant parents are told in antenatal classes that breast milk production works on a basis of supply and demand; what the baby asks for, the body produces. Sounds simple, right? But for some people, establishing a supply that delivers what their baby needs to be satisfied (more information on how to identify this, coming up) is a struggle that they hadn’t anticipated.

If you are worried about your milk supply, please reach out for help from a feeding specialist, midwife, health visitor, infant feeding team or GP.

So, where to begin with this confusing topic? To get started, WH asked two experts, Imogen Unger an IBCLC lactation consultant and specialist neonatal intensive care (NICU) nurse, and Stacey Zimmels, an IBCLC lactation consultant, speech and eating therapist, and founder of FeedEatSpeak, for their advice on what to do should this issue affect you.

How common is low milk supply?

Estimates of how many people are likely to be affected by low milk supply are hard to come by, as it is a fairly understudied area of women’s health. That being said, one study puts the prevalence at as high as 10-15% of people who breastfeed.

Both Zimmels and Unger agree that the data should be taken with a pinch of salt, though. They note that there are lots of reasons for low milk supply – some to do with the parent, some to do with the baby – that can’t really be grouped together.

What causes low milk supply?

According to Zimmels, establishing the cause of low milk supply is the most important first step to being able to address the issue. You can do this alongside a professional lactation consultant, if that's something you can afford (some NHS trusts offer infant feeding advice for free, though, so it’s always good to check).

In some cases, low milk supply can be caused by various conditions affecting the parent, such as diabetes, polycystic ovary syndrome (PCOS), insufficient glandular tissue (IGT), thyroid issues, breast surgery or injury.

Use of certain medications, either before, during or after birth can also have an impact, so it’s a good idea to check with your doctor if anything you are taking could mess with your milk production. ‘It [low milk supply] can also occur due to factors that arise in labour and delivery such as retained placenta or extreme blood loss,’ Zimmels explains – though she cautions that this is rare.

According to both Unger and Zimmels, low milk supply is more commonly caused by a lack of or interruption to the stimulation that breasts need from soon after birth for a plentiful supply to be established and maintained.

There may be multiple reasons for a lack of or interruption to breast stimulation, such as:

  • Separation from your baby after birth — either because they are ill or premature and may need support in a NICU

  • Scheduling or limiting the times of a feeds rather than feeding responsively

  • A delay in your milk supply ‘coming in,’ interrupting the beginning of your feeding relationship and potentially causing early supplementation

  • Dummy use (which might mask your baby's early feeding cues)

  • Medications used during birth making a baby sleepy and therefore too tired to feed frequently or effectively

  • Having had an instrumental birth that can cause your baby to be in pain and therefore not latch effectively

  • Offering only one breast per feed

  • Poor positioning and attachment or a shallow latch (nipple pain could indicate this)

  • Poor tongue function or tongue tie

  • Topping your baby up with formula

  • Leaving a sleepy baby to sleep for long periods, thereby reducing the frequency of their feeds

How do I know if my supply is low?

If your baby is producing the appropriate number of wet and dirty nappies for their age and is growing steadily after their first 2 weeks, then they are almost certainly getting enough milk. If this is not true for your baby, then you can ask your midwife, health visitor or breastfeeding specialist for their advice.

Zimmels says that the following are not signs of low milk supply, but often women doubt their supply when they occur:

  • Breasts soften or leak less/stop leaking (after six weeks this is normal)

  • Baby will drink milk from a bottle after a breast feed

  • Baby is cluster feeding (takes from both breasts and then doesn’t seem settled and starts to root again for more milk). This is a normal phenomenon in infant feeding and can happen daily, sometimes for a period of hours

  • Baby won’t settle or be put down after a feed

  • Baby is taking a long time to feed

  • Frequent night waking even after the early weeks and months

  • Not being able to pump much milk — pumping is not an accurate indicator of milk supply

How do I fix low milk supply?

‘Some women may need to return to feeding their baby responsively and offer the breast more often,’ she explains. If the baby is not feeding effectively, this will need skilled assessment and support.

If a tongue tie is present, it may require a division,’ she says. ‘Women may need to introduce pumping in addition to breastfeeding to increase supply in the short term, and there may be women for whom galactagogues [substances that aid with the production of milk, such as domperidone] are suggested — though this should always be under medical supervision.’

Tips to boost low milk supply

Suspect that your supply is low? From Unger, here are some at-home tips to boost your milk supply:

  • Skin-to-skin contact with your baby – great for boosting prolactin, slowing down and supporting feeding behaviours

  • Guided relaxations, listening to music and looking at videos or photos of your baby as you express to help to boost your oxytocin levels, which helps with milk let-down

  • Pumping frequently (aiming for around 8 times in 24 hours) with the best pump you can afford and especially at night when your levels of prolactin (the milk-making hormone) are higher. You can also try ‘power pumping’ and pumping with both breasts at the same time

  • Use hands to massage while pumping, combine hand expressing and pump expressing

  • Make sure you have the right size flange on your pump and that all the parts are working well

Do I need to supplement with bottles?

‘In some cases of low milk supply, your baby may need supplementing,’ says Zimmels. ‘For most this is a short term measure whilst working to build or rebuild milk supply, and in other cases this can be alongside breastfeeding for a longer period of time.’

Supplementation, she says, does not need to be with formula and can be with breastmilk, which would come from the pumping a mother is doing to increase supply. ‘If there is not enough breastmilk then donor breast milk or formula are alternatives.’ Supplementation also does not need to be via a bottle, she says. ‘In the early days it can be via syringe or finger feeding and long term via a supplemental nursing system.’

How long does milk supply take to settle?

Typically your supply will settle around six weeks post birth, says Unger. ‘Around this time you may find that your breasts do not feel “full” anymore,’ she says.

‘If your baby is gaining weight appropriately, continuing to have the expected number of wet and dirty nappies, and feeding the expected number of times per day then don’t be concerned.’ If at any time you are unsure, says Unger, then please reach out for help from a feeding specialist, midwife, health visitor, infant feeding team or GP.

Can I avoid low milk supply?

Beyond all of the above, getting ahead of breastfeeding before the birth can help to avoid any issues afterwards. Hand expressing colostrum (first milk) from around week 36 of pregnancy has been shown to help to stimulate milk production, and provide food for your baby to avoid supplementation if there are any issues in the days after birth.

In addition to this, if breastfeeding is important to you, working with a trained professional before the birth to come up with a feeding plan can help to reduce the likelihood of early interruptions stated above that have been shown to cause low milk supply.

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