Reasons for Low Milk Supply

There are many possible reasons for a low milk supply, from infrequent breastfeeds or a poor latch (the way baby attaches to the breast) to a pre-existing condition in a mother’s medical history. For most women, a low milk supply can be easily prevented or corrected with the right information and timely support from an IBCLC lactation consultant and/or a health care professional. However for a small minority of women circumstances may mean that exclusive breastfeeding is not always possible.

This article

This article looks at some of the reasons for low milk supply and is a sister article to No Breast Milk After Delivery.  For general ideas to increase a breast milk supply see How to Make More Breast Milk and to gauge how much milk your baby is getting see Is My Baby Getting Enough Milk?

Twelve reasons for low milk supply

Understanding why there isn’t enough milk is the first step to finding a solution. There is often more than one reason for low milk supply. Reasons may be baby related, for example a baby who struggles to latch, or mother related for example if a mother has insufficient glandular (milk-making) tissue, or both. Possible reasons include:

#1 Breast milk coming in late (delayed onset of lactation)

Colostrum (the first breast milk) is present in the breasts at a low volume even before a baby is born. A couple of days after birth, the volume of breast milk increases and is often known as “milk coming in”. When this rise in volume doesn’t happen within two to three days it is said to be late or delayed. Delayed lactation is a risk factor for low milk supply particularly if the mother doesn’t have the correct support and information along with personal determination. Our sister article No Breast Milk After Delivery discusses how birth practices, early breastfeeding management and medical issues can be causes of a delayed milk supply.

#2 Poor breastfeeding management

One of the biggest risk factors for low milk supply is not removing enough milk from the breasts in the early days (and nights!) after birth. In fact good milk production relies on regular, efficient breast drainage for several weeks. Poor milk removal might be due to a baby not sucking well (#3) or poor breastfeeding management for example:

  • Separation from your baby after the birth, or a late start to breastfeeding without frequent hand expressing to empty the breasts
  • Not feeding often enough—babies often need to feed every hour or two at first see How Often Should a Newborn Feed?
  • Scheduling feeds or restricting the length of feeds instead of feeding on demand
  • Delaying feeds by using a pacifier
  • Keeping to one breast per feed instead of offering both breasts per feed
  • Leaving a sleepy baby to sleep for long periods
  • Leaving breasts very full and engorged when milk first comes in
  • Topping baby up with industrially made formula which can interfere with breastfeeding frequency and milk supply.

If frequent and thorough milk removal doesn’t happen, milk production will start to shut down.

How supplemental feeds interfere with milk production

  • Less time at the breast, less milk. Topping up with formula can interfere with breastfeeding because once a baby is full of formula, they will sleep more and feed less at the breast. If you’re not emptying your breasts by hand or pump to compensate and your baby is feeding at the breast less often, breasts will quickly make less milk. This can soon lead to a downward spiral of more and more supplements and less and less breast milk until there is a really low milk supply.
  • Nipple confusion. Introducing a bottle teat can also cause nipple preference or nipple confusion for some babies so that they prefer the bottle.

With good support, formula supplements are seldom needed. However there may be situations where your baby does need supplements of human donor milk or formula e.g. if he is very jaundiced or your milk supply is very late to come in after delivery. Or later on, if your milk supply has dwindled and your baby isn’t gaining any weight.

Until you can get good skilled help with breastfeeding; hand expressing or pumping every couple of hours or more can help protect and boost your milk supply and provide breast milk for top ups.

Mother breastfeeds skin to skin
Milk removal is most efficient when a baby has a good mouthful of breast tissue as well as the nipple in their mouth (a deep latch)

#3 Baby’s breastfeeding skills

A baby who can’t remove milk from the breasts properly can lead to a lower milk supply in the same way as poor breastfeeding management (#2). Just because a baby is in position and seems to be latched on to the breast every two hours or even “all the time”, doesn’t necessarily mean that he is draining the breasts efficiently or even swallowing much milk. Milk removal is most efficient when a baby has a good mouthful of breast tissue as well as the nipple in their mouth (a deep latch), and enough stamina to feed effectively. Poor milk transfer could be due to factors unique to baby or difficulties with a mother’s unique anatomy (#5). Causes for poor breastfeeding skills might include:

  • Medications used during the birth can make a baby sleepy and too tired to suck properly
  • If baby is in pain or discomfort following a medically managed/traumatic birth
  • Prematurity or being small for dates
  • A shallow latch or poor positioning (sore nipples usually indicate a problem with latch)
  • A poorly baby e.g. cardiac or respiratory problems or severe jaundice
  • A sleepy baby may be happy to sleep instead of feed
  • A baby with low or high muscle tone
  • Anatomical variations such as a small jaw (micrognathia), or cleft palate,
  • Poor tongue function or tongue-tie
Mother lying down to breastfeed
If frequent and thorough milk removal doesn’t happen, milk production will start to shut down

#4 Birth issues

Several of the reasons for low milk supply overlap each other. A difficult or medically managed birth can lead to a delay in milk coming in (#1), poor breastfeeding management (#2), poor breastfeeding skills (#3) and less competence to cope with nipple challenges (#5). Medications used during the birth or the early lactation period may also make a baby more sleepy or less competent at breastfeeding. Some medications are associated with reducing a milk supply (#10). For more information on this topic see No Breast Milk After Delivery.

Keep milk flowing. Good clues for milk transfer are discussed in Is My Baby Getting Enough Milk? These include looking and listening for swallows of colostrum, watching the jaw for active sucking and monitoring the amount of baby poop (when milk goes in, poop comes out!). If baby can’t breastfeed well; contact a breastfeeding specialist to help you. And meanwhile hand expressing or pumping every couple of hours or more can help protect your milk supply and provide breast milk for top ups until breastfeeding improves.

#5 Nipple challenges

Sometimes a baby may find it difficult to breastfeed and drain the breasts efficiently due to variations in his mother’s anatomy making feeding more challenging at first. However a mother and baby can often overcome any difficulties with anatomy with the right skilled help. Examples of situations that can be challenging include:

  • Flat or inverted nipples
  • Very large, very long or differently shaped nipples e.g. double nipples or nipples with a skin tag can make it more difficult for a baby to latch deeply.
  • Large breasts—causing a mismatch in breast to mouth fit
  • Very tight inelastic breast tissue can make it harder for baby to latch
  • Nipple piercing may have led to scarring or closure of nipple pores which can block milk flow—see Breastfeeding With Pierced Nipples.

#6 Insufficient glandular tissue

When milk truly doesn’t seem to come in after birth (rather than it started to come in but was suppressed by poor management, poor breast drainage or other medical issues) it may be due to insufficient glandular tissue (IGT). Other names for this include primary lactation failure, lactation insufficiency, mammary hypoplasia, or hypoplastic breasts. IGT is rare and normally there might be some clues in your medical history or pre-existing physical characteristics. Indicators might include having hormone or endocrine issues (#8), very small and widely spaced breasts or tubular shaped breasts, if one breast is markedly different to the other, if your breasts hadn’t enlarged and been tender during puberty or pregnancy or if there wasn’t a feeling of fullness after the birth.1

  • Breast tissue can continue to grow through each pregnancy and lactation experience so even if you don’t have enough milk for your first baby the chances are you will have more for a subsequent baby.
  • Getting breastfeeding off to a good start can maximise the milk you do have—seek good breastfeeding help.
  • Supplementing at the breast with the help of a supplemental nursing system can help mothers with IGT have a breastfeeding experience. Ruth Cumming shares her story of breastfeeding with IGT here Making the Most of What We Have.

For more information see Breastfeeding with Hypoplasia Insufficient Glandular Tissue, Breastfeeding Today, by Diana Cassar-Uhl.

#7 Breast surgery or trauma

Successful lactation depends on certain structures in the breast being intact and fully developed. Any previous surgery to the chest area has the potential to damage important nerve pathways and ducts and compromise glandular tissue in the breast. Examples that could affect milk production include:

  • Breast reduction surgery
  • Breast implants (augmentation surgery)
  • Lumpectomy or biopsy
  • Incision and drainage of an abscess
  • Past trauma to the chest area including having a chest drain as a premature baby
  • Radiation or burns to the breast
  • A past or present breast infection can lower milk supply in the affected breast.
  • Anything affecting breast development during puberty
  • Spinal cord injuries or any surgery affecting the brain and pituitary gland
  • Placental insufficiency: breast tissue develops during pregnancy under the influence of hormones from the placenta so if the placenta is not functioning correctly breast development may be slowed or incomplete.2

#8 Hormonal or endocrine disorders

Several hormones are important for making milk (including prolactin, thyroid hormones, insulin, and cortisol) and releasing milk (oxytocin).  If a mother has an underlying hormonal imbalance or needed fertility treatment to get pregnant this could flag an issue with milk production or let-down of milk. Possibilities include:

  • Polycystic ovary syndrome (PCOS) has an association with low milk supply for some mothers. See Polycystic Ovary Syndrome and Breastfeeding for further information.
  • Thyroid issues may affect both oxytocin and prolactin (breastfeeding hormones) and, if not diagnosed and addressed, could be a factor for low milk supply. The thyroid gland needs iodine to function and iodine requirements are doubled during pregnancy and lactation—too much or too little can both affect normal function (Marasco and West, 2020).
  • Diabetes or gestational diabetes is a risk factor for low milk supply or milk coming in a day or so later than usual for some mothers. Monitoring blood sugar and insulin levels carefully can help to keep the milk supply stable.
  • Pregnancy while breastfeeding can cause a milk supply to drop due to the changing hormones.
  • Gestational ovarian theca lutein cysts (see No Breast Milk After Delivery for further information).
  • Luteal phase defect is associated with insufficient progesterone in the luteal phase (after ovulation) of the menstrual cycle and is associated with IGT 3
  • Synthetic oxytocin during birth may interfere with normal oxytocin function (Marasco and West, 2020). Oxytocin affects the let-down reflex (release of milk from the breast) so anything interfering with this could affect milk supply. Oxytocin can be inhibited by nerve damage, stress, and negative associations such as birth trauma and post traumatic stress disorder.
  • Prolactin levels. There are a number of risk factors for low prolactin (hypoprolactinemia) including certain drugs, childhood cancer, a family history alcoholism, high body mass index (BMI), Sheehan’s syndrome, and insufficient calcium in the diet (Marasco and West, 2020).
  • Being overweight or obese with a high BMI is said to be a risk factor for delayed onset of lactation which can be associated with a low milk supply in the early days of breastfeeding.4567 For more information on breastfeeding challenges related to obesity see Best Breastfeeding Diet and Foods to Avoid.
  • Infertility associated with hormonal issues may affect lactation. Fertility treatment has been associated with a shorter period of breastfeeding in research (Mohrbacher, 2020 p 437).
  • Age—There are a few studies to suggest that being an older mother could be a risk factor for milk coming in late or having a low milk supply.891011 However it is difficult to separate older age as a risk factor from a higher chance of other factors that might affect milk supply such as health, fertility or hormonal issues that could be more likely with advancing age (Marasco and West, 2020). Of interest when considering age of mother is that grandmothers have relactated successfully in countries where breastfeeding is accepted as the cultural norm. 12
  • Other health conditions may be related to low milk supply such as autoimmune disease although more research is needed (Marasco and West, 2020).

Checking hormone levels

A blood test can check the levels of hormones needed for breastfeeding in your blood. A table for tests for hormonal causes of low milk production can be found in Breastfeeding Answers A Guide for Helping Families page 443 and expected prolactin levels at baseline/after breastfeeding can be found in a table on page 410 (Mohrbacher, 2020). Your IBCLC lactation consultant may have access to this book.

#9 Diet and herbs, vitamins and minerals

What we eat can affect milk quality in subtle ways and in some cases can affect the quantity of milk. Research is showing that a number of nutrients are important for optimal milk production such as protein, zinc, fibre, calcium, and iron. Diet can also affect our metabolic health which may in turn affect milk supply.

  • Some herbs e.g. sage, parsley, or mint can reduce a milk supply if taken in excess, other foods and herbs are thought to increase milk supply. See Best Breastfeeding Diet and Foods to Avoid and What is a Galactagogue? for more reading.
  • Having low iron levels can impact on milk supply; supplemental iron from your doctor and iron rich foods will help to replenish your iron stores 13.
  • Too much Vitamin B6 is linked with low milk supply for some mothers.
  • Severe calorie restriction can reduce milk supply (Marasco and West, 2020)
  • Excess alcohol can reduce milk supply
  • Low vitamin D may be linked with low supply for some mothers although more research is needed (Marasco and West, 2020).

The book Making More Milk: The Breastfeeding Guide to Increasing Your Milk Production, Second Edition includes a discussion of specific foods, herbs, vitamins and minerals that might maximise milk supply in specific situations.

close up of baby breastfeeding
A breastfeeding specialist such as an IBCLC lactation consultant can help you maximise your milk production

#10 Medications

Certain medications and hormonal birth control may reduce milk supply. Individual medications can be checked in the resources listed in Medications and Breastfeeding.

  • Birth drugs. Certain drugs used in pregnancy or childbirth can lower milk volume e.g. some medications used to prevent premature birth or help the baby’s lungs mature may affect milk supply along with insulin, some antidepressants14, and some antinausea medication (Marasco and West, 2020).
  • Hypertension during pregnancy (when blood pressure is higher than normal) is a risk factor for low milk supply, either via affecting breast development during pregnancy—because hypertension may affect the placenta—or some of the drugs used for treatment may suppress lactation1516. High blood pressure that starts during a pregnancy after 20 weeks gestation is called gestational hypertension which encompasses pregnancy induced hypertension (PIH) or preeclampsia (also known as toxaemia). HELLP syndrome (NHS link) is a severe form of this.
  • Hormonal birth control including the pill, contraceptive implants or hormone impregnated intrauterine devices can affect milk supply in some cases, see Can You Get Pregnant While Breastfeeding? for more information. Postpartum tubal ligation (having ones tubes tied) has also been linked with low milk supply for some mothers 1718.

#11 Pollution

  • Smoking—including smoking marijuana can reduce milk supply. Nicotine levels are high in breastfeeding women and nicotine is associated with reducing prolactin—an important hormone for making milk 19 while a study with rats queries whether oxytocin and therefore milk release could also be affected20.
  • Environmental contaminants. Exposure to certain chemicals in the environment could affect milk supply if they interfere with the normal hormone function needed for making milk. 2122 Lee and Kelleher explain:

Numerous chemicals such as atrazine and dioxin (in herbicides), bisphenol A (BPA), and dibutylphthalate (in plastics), nonylphenol (in laundry and dish detergent), polybrominated diphenyl ethers (a flame retardant), and perfluorooctanoic acid (PFOA; in cleaning products and pesticides) have been observed to disrupt mammary gland function.

#12 Being half hearted from the start

Planning to mix feed or “try” to breastfeed, doubting whether breast milk can satisfy a baby, being embarrassed, having a lack of information and support, and not getting early help for problems—are all possibilities for “low milk supply” even when sometimes it isn’t a low supply at all. Having mixed feelings about breastfeeding can lead to reliance on formula and a self fulfilling prophecy when milk supply drops (see #2 above).

What can I do if I have low milk supply?

Find good support

Finding a good breastfeeding specialist such as an IBCLC lactation consultant to support you to maximise your milk production will be invaluable. They will be able to share good breastfeeding tips, help you with positioning, and latching and make a specially tailored plan for you and your baby. See How to Make More Breast MilkHow to Increase Milk Supply When Pumping and Baby Not Gaining Weight for more reading.

Supplement at the breast

For mothers who need to supplement additional milk, supplementing at the breast with a commercial or Home Made Supplemental Nursing System can help maximise supply, preserve the breastfeeding experience and provide more time in skin-to-skin contact—with all its many benefits.


There are many reasons that could contribute to a low milk supply. Knowing the possible reasons for a milk supply coming in late, or never seeming to get established can help prevent it happening, maximise the mother’s milk supply if it has already happened or prevent low milk supply with a subsequent baby. It will also provide an explanation for the mother who is grieving for her lost breastfeeding experience. With the right help and information, breastfeeding works well and the number of mothers who truly have low milk supply are a small minority.