Breast Feeding Feeding

Why Does One Breast Produce More Milk Than The Other?

One surprising aspect of breastfeeding that you might have noticed is that one of your boobs produces more milk than the other.

While discovering you have an uneven milk supply may understandably catch you by surprise, the first thing worth stating is this is a common occurrence for women who breastfeed.

Having one boob produce more milk than the other isn’t something you need to typically worry about, provided your baby is getting enough milk overall and their nutritional needs are being met.

However, if you are worried that your body isn’t producing enough milk for your baby, or are self-conscious about one breast looking bigger than the other, you probably want to know why one of your breasts is producing more milk than the other, and what you can do to fix the issue.

Why Does One Breast Produce More Milk Than The Other?

Determining why one breast may produce  more milk than the other isn’t always straight forward, because it might be caused by a number of reasons, and some are often combined.

Here are 5 of the most common causes:

1. Your Baby Prefers Ones Side vs The Other

It’s not uncommon for a baby to prefer feeding from one side compared to the other.

It could be down to them finding one boob easier to latch on to, especially as a lot of women have different shaped nipples between their left and right side.

So if your baby does have a favorite side, this could be one reason for one of your breasts producing more milk than the other.

To understand the knock-on effect this causes we need to remember that (from the perspective of your body) making breastmilk is a game of supply and demand.

And what this means in practical terms is that the more milk that is emptied from one of your breasts, the more milk your body produces in order to keep up with demand.

baby in pink shirt lying on white textile

2. You Prefer To Nurse From One Side

On a similar note, you might want to consider if you have preference when it comes to which side you offer your baby.

It’s actually quite common for mom to have a preferred side, and sometimes this preference isn’t even a conscious decision!

For example if nursing from one side is comfortable and the other side gives you even a little bit of discomfort, you will naturally prefer to offer the comfortable side to your little one.

You might also find that holding your baby in one particular position – for example supporting their body with your dominant arm, or alternatively keeping your dominant hand free so you use your cell phone – might all lead you to favoring one particular side, which will lead to that side producing more milk.

3. You Don’t Alternate Breasts Between Feeds

Tied to the above but worth calling out separately is that not alternating which breast your baby nurses from between one feed to the next could also be causing your uneven milk supply.

Let’s say for example your baby just has a good feeding session on your left side and then fell asleep.

And a few hours later you offered them the left boob again to start their feed.

In simple terms what this will do is encourage your body to produce plenty of milk in your left side, and less in your right side.

4. One Of Your Breasts Has More Milk Making Tissue

Another potential cause of this variance in supply could be because one of your boobs has a higher amount of mammary or glandular tissue.

Without getting too technical, mammary tissue consists of around 20 lobes that produce milk.

And if one of your breasts has bigger ducts, it might result in that side having a higher supply compared to your other side.

person feeding baby from feeding bottle

5. One Side Has A Slower Letdown

If you haven’t heard the term letdown before, what this refers to is the release of milk from your boob.

If this letdown is too fast on one side, it will result in your baby favoring the other side, because the side with the less forceful letdown will be more comfortable.

And as explained above, preferring (and therefore emptying milk from) one side more often than the other will lead eventually lead to one of your breasts making more milk vs the other.

Is It OK If One Side Produces More Milk Than The Other?

Probably the most common question from women with an uneven milk supply is whether they should be concerned that one breast produces more milk than the other.

The answer is typically no, there is nothing to worry about.

As long as your little one is getting enough milk, you can take comfort in the fact that your body is producing exactly what your baby needs.

However if there’s any doubt in your mind you may want to speak with your midwife or doctor, particularly if you have noticed your milk supply drop from one side suddenly.

Related: Your Must Have Baby & Toddler Feeding Guide

How To Increase Milk Supply In Your Other Breast?

As we covered in a recent article, there are definitely some things you can do to even out your milk supply, including:

  1. Offer your baby the side that is producing less milk first, because the more a breast is emptied, the more your body will replenish the supply.
  2. Pump or express the side that produces less milk. Incidentally if you then have some excess milk, here are some great ideas on what to do with extra breast milk.
  3. Alternate which side your baby starts their feed from.
  4. Massage the lower producing side, as this can help stimulate more supply.


Having one breast produce more milk than the other is a very common occurrence among moms who nurse.

Typically this is more of a cosmetic issue than anything else and there’s usually nothing for you to be concerned about, because as long as your baby is getting enough milk, your body is doing a good job at providing for your baby.

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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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