Why do some women's breasts not make enough milk to meet their baby's caloric needs?

"She looked from Leonie to Therese and she smiled. "Of course I fed you both, silly. I had plenty of milk didn’t I …." Rose in her chair by the fire, feet up, blouse undone, a lapful of babies, a shout of joy, the smell of milk, there, my dears, there." Michele Roberts, Daughters of the House p 169

"Flourish ….. To grow luxuriantly, or thrive in growth." The Macquarie Dictionary p 687

To make milk you need to take milk from your breasts

Increasing the amount of breast milk you remove increases the amount of breast milk you produce.

However, no-one knows exactly how why this happens. There are various models used (which are often presented as if they are fact!) In the Possums programs, I work from the NDC two-part model about milk production. The research findings from which I've developed this model are in the modules for health professionals. Here's what I think, drawing on the latest research.

1. When the baby removes milk more often, there is less backpressure building up in the milk glands. Backpressure is known to downregulate milk supply due to its mechanical effects on the lactocytes and milk glands. You can find out about this here.

2. Suckling causes spikes of prolactin, which stimulate the stem cells which are always present in the alveoli and ducts and connective tissues of your breast, promoting their growth and differentiation into new milk glands.

The worry that baby is not receiving enough milk is the main reason women give for starting formula

The most common reason women give around the world for ceasing breastfeeding is "not enough milk."

You have what we might call a 'full' milk supply if you're able to produce enough milk to meet your baby's growth needs in the first six months of life without supplementing with formula or donor milk. But the amount of milk produced daily by women with 'full' milk supply varies enormously. You can find out how much milk breasts make here.

It's very common to have concerns about your milk supply. At least a third or even up to about two-thirds of women report that they don't have enough milk in the first weeks after their baby's birth. Unfortunately, we often have milk production problems because of our health systems' blind spots about breastfeeding.

You - like many other breastfeeding women - might be worrying that you don't have enough milk because your baby doesn't seem satisfied. A dialled up baby is not necessarily a hungry baby, but if you have a baby who is dialled up as a pattern over time, one of the first things to explore is whether baby’s gaining weight well. There are other things that can make your baby appear hungry, too, when that's not the case.

• You can find out how to tell if your baby is getting enough milk here.

• You can find out what are not signs of low supply here.

• You can find out about your baby's sensory motor needs here.

• You can find out why you don't need to burp your baby here.

The three main causes of low milk supply

Usually many things interact together to effect your milk supply, and some women have much more buffer built into their supply settings than others, for genetic reasons. This is one reason why you might have had exactly the same breastfeeding experiences as your friend, but your friend is making plenty of milk for her baby down the track, and you aren't.

It's usually not because of innate pathologies in your baby's capacity to suck, though you'll often hear this.

1. Your milk production settings might be affected long-term if not enough milk is removed from your breasts during the sensitive first days after your baby's birth

The first cause of low supply is not enough milk removal in the first hours and days of your baby's life. The first day or first few days after your baby is born set the trajectory of your breasts capacity to produce milk.

For example, a woman’s supply by the end of the first fortnight predicts her supply at the end of six weeks. You can find out about this here.

Not enough milk removal at the very beginning means that your milk supply might peak at a lower setting than it otherwise would, and this is likely to persist for the rest of your breastfeeding relationship with your baby.

Lots of women manage to heroically repair their supply and go on to exclusively and happily breastfeed their baby despite a very difficult start with breastfeeding, and lots of formula supplementation. For others, no matter how hard they try, exclusive breastfeeding never becomes possible. All we can do is give it our best, accepting that much in life - and in breastfeeding - is outside our control.

2. The most common underlying cause of low milk supply is too much backpressure in your milk glands

Not making enough milk to meet your baby's needs without supplementation very commonly results from too much backpressure in your milk glands is caused by not enough milk removal, which results in decreased or downregulated milk production. You can find out about the mechanical effects of backpressure in your milk glands here.

Too much backpressure results from

• Baby's positional instability at the breast, which causes breast tissue drag and inadequate milk removal. You can find out about this here.

• Not being able to resolve nipple pain and damage, which makes it very difficult to breastfeed often enough. You can find out about this here.

• Having severe or repeated breast inflammation. You can find out about this here.

• Advise to space out breastfeeds. You can find out about this here.

Unfortunately, although formula use can be essential for your baby's safety (given the difficulty many families face accessing donor milk), using formula can also quickly decrease your breast milk supply. This is because your baby has less of an appetite drive to take milk from your breasts. You can find out about formula use here.

3. Some women are never able to breastfeed their baby exclusively due to an underlying medical condition

There is a difference between a temporary low supply which isn’t enough to meet your baby’s needs for growth but which can be addressed through various management strategies, and a low supply due to medical conditions which can’t be fixed, only managed as best we can.

It is mostly not possible to know just how much any medical condition is going to effect your supply, until we’ve put in place all the strategies which optimise your milk production. Unfortunately, women often don’t receive good advice about the basics of fit and hold and frequent flexible breastfeeds.

Yet good fit and hold and frequent flexible breastfeeds are essential for making the most milk you possibly can, even when you are managing a medical diagnosis which is known to affect milk supply.

You can find out about your supply and

• Type 1 or type 2 diabetes here

• Polycystic ovary syndrome here

• Iron supplementation here

• Insufficient glandular tissue here.

Please note: Possums Breastfeeding & Lactation does not yet address prematurely born babies and breastfeeding.