Causes of low supply from birth

Why have I never had enough milk?

There are many reasons why a mother may have a low milk supply from birth. They fall into  groups: (1) problems related to labour or delivery; (2) hormonal problems; (3) breast problems such as surgery or lack of development; (4) illness in the mother around the time of delivery; and (5) genetic conditions. Some mothers with a low supply don’t have any of these conditions. Some mothers will always have a low milk supply, but others, particularly those whose problems are related to delivery, may have a full supply with the next baby. Some mothers worry that they have a low milk supply because they are not eating or drinking enough or are getting too little sleep. Those are rarely the cause of a low supply.

A) Describing causes for never having had enough milk

While most mothers have a full milk supply, a small number of mothers simply do not have enough milk to meet the baby’s needs and have never had enough. This is different from having a reduced milk supply (a milk supply that is full right after birth but decreases within weeks or months). Milk can also come in late.

Some mothers worry that they have a low milk supply because they are not eating or drinking enough or are getting too little sleep. Unless a mother is severely underfed or malnourished, the quality and supply of her milk should be normal.

Please work with your health-care providers if you feel that you do not have enough milk.

Possible reasons for a low milk supply fall into six groups.

B) Causes related to labour or delivery

Causes related to labour or delivery include: 

  • Lack of milk removal and breast stimulation related to:
  • Having a premature delivery. 
  • Losing a lot of blood (hemorrhage) or having a big drop in blood pressure
  • Medication used to prevent early labour (Bjelakovic 2016)
  • Not passing all of the afterbirth with the delivery (a retained placental fragment)
  • Severe illness in the mother  

D) Causes related to breast problems

Causes of low milk supply related to breast problems include: 

E) Causes related to illness in the mother around the time of delivery

Causes related to illness in the mother around the time of delivery include: 

F) Causes related to genetic conditions

Causes of low milk supply related to genetic conditions include: 

G) Unknown causes

We have found that some mothers who have never had enough milk do not have any of the above conditions. There is a small amount of evidence that the mother’s genetics, diet, and environmental toxins may prevent the normal development of the breast. Research continues (Lee 2016).

H) Milk supply with the next baby

Some mothers, particularly those with insufficient glandular tissue or who have had extensive breast surgery, will have a low milk supply with each baby. Other mothers, such as those who have had problems related to delivery, may have a full milk supply with the next baby.


Bjelakovic L, Trajkovic T, Kocic G, et al. The Association of Prenatal Tocolysis and Breastfeeding Duration. Breastfeed Med. 2016 Dec;11:561-563

Golan Y, Assaraf YG. Genetic and Physiological Factors Affecting Human Milk Production and Composition. Nutrients. 2020 May 21;12(5):E1500

Kelleher SL, Gagnon A, Rivera OC, et al. Milk-derived miRNA profiles elucidate molecular pathways that underlie breast dysfunction in women with common genetic variants in SLC30A2. Sci Rep. 2019 Sep 3;9(1):12686
Lee S, Kelleher SL. Biological underpinnings of breastfeeding challenges: the role of genetics, diet, and environment on lactation physiology. Am J Physiol Endocrinol Metab. 2016 Aug 1;311(2):E405-22
Lee S, Zhou Y, Gill DL, et al. A genetic variant in SLC30A2 causes breast dysfunction during lactation by inducing ER stress, oxidative stress and epithelial barrier defects. Sci Rep. 2018 Feb 23;8(1):3542

Rivera OC, Geddes DT, Barber-Zucker S, et al. A common genetic variant in ZnT2 (Thr288Ser) is present in women with low milk volume and alters lysosome function and cell energetics [published online ahead of print, 2020 Apr 22]. Am J Physiol Cell Physiol. 2020;10.1152/ajpcell.00383.2019