Breast Feeding Feeding

Why Does One Breast Produce Less Milk? (Causes & Solutions)

If you have recently started your breastfeeding journey you may have noticed that one of your boobs produces less milk than the other.

While this observation might have surprised you, it’s worth stating upfront that an uneven milk supply is a very common occurrence among moms who nurse.

If you believe your baby is getting enough milk and their nutritional needs are being met, then there’s no need to worry, and you’re probably best continuing as normal.

But if you are concerned that you’re not making enough milk for your baby, or are uncomfortable having one breast appear larger than the other, you might be curious as to why one of your breasts is producing less milk than the other, and what you can do to resolve the issue.

Let’s take a look.

Why Does One Breast Produce Less Milk Than The Other?

Figuring out why one breast may produce less milk than the other isn’t always easy, because it could be down to several reasons, some of which may be combined.

Some of the most common reasons why this could be happening include:

1. One Breast Has Less Milk-Making Tissue

One possible reason is that one of your breasts has a lower amount of mammary or glandular tissue.

Mammary tissue is made up of 15 to 20 lobes that produce milk, and the key thing to be aware of is that because a woman can have a natural variation between her breasts, the size of your ducts may vary between your left and right boob.

So this variance between milk-making tissue in each breast could be the reason why your supply is uneven.

2. Differences In Letdown

On a similar note, the natural variation from one side of your breast to the other might mean that one of your breasts has a stronger letdown than the other.

Letdown is the release of milk from your breast, and if it’s too forceful, your baby may stop feeding from that breast and prefer the other side, which can cause an uneven supply (more on why feeding and emptying a breast is important shortly).

Person Holding Baby's Hand

3. Differences In Nipple Shape

Another thing that can result from this natural anatomical variance is that the shape of your nipples may vary between your boobs.

This may not sound like a big deal, especially if the variance is small, but having one nipple bigger than the other, or in a more extreme case having an inverted or flat nipple, may lead to your baby preferring one breast over the other.

4. Your Baby’s Preference

It could perhaps be due to the reasons above or down to something else, but it’s quite common for babies to prefer nursing from one of mom’s breasts and not the other.

Many times a baby will find one breast is more comfortable or easier to latch on to than the other, and if this is the case with your little one, they may have a favorite side that is contributing to your uneven supply.


Because the more one of your breasts is emptied, the more it will produce.

So if your baby is not feeding enough on one side, that breast will actually produce less milk than the side that is regularly emptied.

5. Your Preference

It’s not uncommon for mom to also have a preference, and to therefore favor one breast over the other.

Maybe it’s down to what position you’re most comfortable holding your baby in, or maybe it’s not even a conscious decision, but feeding your little one from one breast more than the other can cause you to have an uneven supply.

A Mother Sitting on a Chair while Carrying Her Baby


If you have had an injury or breast surgery in the past then this could be affecting your supply on one side.

While breast surgery can reduce your milk flow because the procedure may have resulted in your milk ducts being cut, even a breast biopsy could lead to one breast producing less milk than the other.

Should You Worry If One Breast Produces Less Milk Than The Other?

It’s only natural for moms to wonder if it’s a problem or concern that one breast produces less milk than the other.

However, provided your baby is getting enough milk, you can rest assured that your body is making exactly what your baby needs.

Related: How To Weigh Your Baby At Home: 3 Simple Ways

But if you are in doubt or are still concerned, then it’s of course worth speaking to your midwife or doctor so they can investigate further, especially if you have experienced a sudden fall in supply in just one breast.

How To Increase Milk Supply In One Breast?

One of the most important things to note about milk production is that it’s a supply-and-demand process.

This means that the more milk that’s emptied from your breasts, the more your body produces.

With this in mind, here are some helpful tips for increasing your supply in one breast.

1. Offer The Slacker Boob First

Many women affectionately refer to the breast that produces less milk as the slacker boob.

Offering the slacker or less productive boob first can help that side to produce more milk, because babies often nurse more vigorously at the start of a feed.

Starting at the side that produces less can therefore encourage that side to start producing more milk, because as we mentioned above, the more a breast is emptied, the more it will produce.

Photo Of Woman Kissing Baby

2. Pump The Less-Productive Side

On a similar note, pumping the less productive side in between and after feeding is another way to take advantage of the supply-and-demand nature of breastmilk production.

If you do this successfully you may then find you have some excess breast milk, which can be great for multiple things including making lotions, having milk baths and soothing sore nipples.

3. Massage Your Lower Producing Breast

Finally, massaging the breast that produces less milk can be a good way to increase production in your slacker boob.

Massaging your breasts in order to produce more milk can be done in three simple steps:

  • Apply a hot, moist compress to your breast before you start to nurse because this can open up your ducts and stimulate letdown.
  • Lightly massage from the top of your breast down and over the nipple using your fingertips.
  • Press on your breast and massage in a circular motion, as this will encourage milk to flow toward your nipples.


An uneven supply is very common when breastfeeding, but as long as your baby is getting enough milk, there’s typically nothing to worry about.

For most women this is purely a cosmetic issue because provided your baby is getting the milk and nutrition needed to grow, your body is doing exactly what it needs to do in order to provide for your little one.

Related: Your Must Have Baby & Toddler Feeding Guide

Tori is mama to 3 year old Isabella and co-founder of Rockinbaby. She has a BSc in Psychology, is a certified yoga teacher and is a working mom. In her free time Tori loves cooking delicious foods and baked treats, entertaining and working out. Learn more about Tori here.

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