Not being able to produce a full milk supply for your baby can be a stressful and upsetting experience for many mothers.

While most mothers can make plenty of milk for their baby (or babies), the evidence for the commonly stated 1-5% of women not being able to produce a full supply is very weak. The reality is that it’s difficult to determine an accurate percentage of mothers who truly cannot produce a full supply.

A significant number of mothers report that they ceased breastfeeding due to a low supply. In many cases, the problem isn’t a primary (inherent) low supply problem, but rather a breastfeeding management issue or a perceived low milk supply.

More Research Is Needed

To obtain an accurate statistic of mothers who truly cannot produce a full supply, mothers who obtained optimal breastfeeding support and management from birth onwards would need to be studied. The percentage of such mothers who were unable to produce a full supply would provide a more accurate statistic of those who were truly unable to.

A recent study found that mutations in a protein called ZnT2 could stop breasts from developing properly, inhibiting the ability of the breast to produce enough milk. Since this study was done on mice, the results may not be relevant for humans, but may form the basis for future research.

It is sometimes said, “I couldn’t (or won’t be able to) breastfeed because my mother couldn’t”. For mothers who cannot make a full supply for their babies, are there any reasons that could be inherited?

Here are 4 possible conditions that likely have a genetic link and could be possible causes of a low milk supply. It is important to note that many mothers with the following conditions can make plenty of milk for their baby (or babies), even though others may struggle.

#1: Diabetes

Diabetes is a disease in which the body doesn’t make enough insulin or doesn’t use it properly.

Research has identified a link between insulin and breastmilk production. If a mother’s body doesn’t make or use insulin as it should, she may have problems making enough milk.

#2: Polycystic Ovary Syndrome (PCOS)

PCOS is a complex hormonal condition with features such as fertility problems, acne, obesity, excess body hair growth and an increased risk of type 2 diabetes.

If PCOS begins around puberty, it may affect a girl’s breast development.

PCOS could potentially affect a woman’s breast growth during pregnancy (an important time when breasts get ready to make milk).

Even if enough glandular (milk-making) tissue is present in a woman’s breasts, hormonal problems associated with PCOS may interfere with her ability to make enough milk. Find out more information including treatment options for PCOS here.

#3: Thyroid Disease

Thyroid hormones play a role in normal breast development and helping the breasts to make milk. When a mother’s body doesn’t make enough of the thyroid hormones, her milk supply may be affected. Some breastfeeding mothers with hypothyroidism (underactive thyroid) struggle to make a full milk supply.

Women who have been appropriately treated for hypothyroidism report they having no problems with their milk supply.

#4: Insufficient Glandular Tissue (IGT)

Breast size has nothing to do with a woman’s ability to make milk. It is the glandular tissue in a woman’s breasts that determines her milk-making ability and breast size does not reflect how much glandular tissue a mother has.

However, some women don’t have enough glandular tissue to make a full milk supply.

Women with IGT tend to have particular breast characteristics such as long tubular-shaped, widely spaced and asymmetrical breasts.

However, women with various breast characteristics can breastfeed successfully. Even if a mother has breasts that look hypoplastic (underdeveloped), she still may be able to make a full milk supply.

What Can You Do?

If you have any of the above conditions, there are things you can do to help prepare for breastfeeding. Even if you struggled breastfeeding your first child, you may be able to successfully breastfeed subsequent children. Speak with an Australian Breastfeeding Association counsellor or see a lactation consultant.

It’s important to know that breastfeeding is so much more than just about the food. It’s also a relationship with your baby. If breastfeeding is important to you, there are ways you can still have a breastfeeding relationship with your baby even if you cannot make a full supply.

Speaking with an Australian Breastfeeding Association counsellor or seeing a lactation consultant can help you:

To work out if your supply is truly low
To try to increase your supply
To be able to maintain a breastfeeding relationship with your baby and make the most of the supply you do have (e.g. by using a breastfeeding supplementer)
Wean from breastfeeding if that would be the best decision for you and your family.