Only One Breast Works When Breastfeeding? Here’s Why

Many breastfeeding mothers notice that one of their breasts makes more milk than the other.

For example, they may notice they can consistently express more milk from one breast than the other, or their baby prefers feeding from one breast or that their breasts are different sizes.

This may make some mothers worry that one of their breasts is not working well.

The good news is that most of the time, this is normal and nothing to worry about.

Here are 5 reasons why you may find one breast works better than the other:

#1: It could be normal

It is normal for one breast to make more milk and typically have a faster flow than the other breast. Often, this is the breast that your baby prefers.

Some mothers might have a nipple that is a different shape or size (e.g. inverted or flat) that may make that breast more difficult for a baby to attach to. Here are 7 tips to try if you have flat or inverted nipples.

#2: Mastitis

If a breast has mastitis, many mothers notice a temporary supply drop in the affected breast. At the same time, her baby may not feed as well from that breast due to the supply drop and/or because the milk tastes saltier. Most of the time however, her baby is still better at removing milk from the affected breast than a pump.

When the mastitis settles down, it is common for babies to want to feed more frequently. This increased feeding is usually enough to boost the supply in the affected breast back up again to where it was before the mastitis occurred.

#3: Baby favours one breast

Most babies prefer feeding from one breast to some degree. This may be because one breast makes more milk than the other or because the baby prefers the flow more from one breast.

#4: Mother prefers feeding from one breast

Without realising it, a mother might preferentially feed her baby from one breast. She might feed first from this breast at more feeds or offer this breast for top-ups. She may do this because she feels more confident and comfortable with positioning and attaching her baby to that breast.

#5: Breast surgery

If a mother has had previous breast surgery, the surgery may affect the milk-making ability of one breast more than the other.

For example, more milk ducts and/or glandular tissue may have been removed from one breast than the other during breast reduction surgery. Or, more nerve damage (affecting the let-down reflex) may have occurred in one breast more than the other.

Tips to even things up

If your baby is being fed according to his individual need, it is OK to do nothing in particular, other than alternate from which breast feeds are begun. This is because each breast will respond to the demands placed upon it.

If significantly more milk is removed from one breast (e.g. because the baby has a strong preference for it), then it will make more milk. If significantly less milk is removed from the other breast, it will make less milk, but the lack of milk made by this breast will be made up by the other breast.

If you’d like to try to even the supply in each of your breasts up, it can help to:

• Offer the least preferred breast first at feeds. This is because a baby typically feeds most vigorously, and takes more milk from, the breast he feeds first from. Be careful to monitor the preferred breast for lumps as doing this could increase your risk of engorgement, blocked ducts or mastitis
• Offer the least preferred breast for top-up feeds such as when your baby isn’t settling easily
• Offer the least preferred side often during cluster feeding periods
• Express for around 5 minutes from the least preferred breast after or between some feeds

With the above tips, most mothers notice their breasts evening out within a few days or so. Most mothers do the above tips for a short time, just until they get the results they are after. Other mothers continue the above tips long-term.

Baby refusing one breast

If your baby typically feeds well from both breasts and then suddenly starts to be very fussy or refuse to feed from one breast, this may be due to:

• Recent vaccination that may make one of your baby’s arms sore, so a particular breastfeeding position may hurt his arm. Once the pain settles (usually within a couple of days at the most), the baby feeds normally again
• An ear infection or other illness. If a baby has an ear infection, he may prefer to lie on one side. If you think your baby might have an ear infection or other illness, see a doctor
• An injury. If your newborn refuses to feed from one breast, see a doctor to check for any injury that may have occurred during birth that may cause a baby pain in certain breastfeeding positions

If your baby is very fussy or refusing one breast, it can help to:

• Feed him in a different position. For example, if he is happy feeding from your left breast in the cradle hold position, but doesn’t like being fed in the cradle hold for the right breast, you could try feeding him in the football hold for the right breast, as he would be in the same position as when he feeds from the left
• Try a baby-led attachment approach. This is where a baby finds his mother’s breast on his own using his instincts. Sitting in a semi-reclined position and placing your baby on your chest facing you with his head just above your breasts is a good position to allow a baby to do this
• Try feeding your baby when he has just woken up or is still half asleep
• Babies who have been in an awkward position in the womb, or who have had a difficult birth, may benefit from an appointment with a trained musculoskeletal therapist, such as an osteopath, physio or chiropractor who specialises in babies.

If your baby is completely refusing one breast, you could express from that side as often as he breastfeeds from the other side to help keep up your supply until he is back feeding from both breasts.

One-sided feeding

It is possible for one breast to make all the milk a baby needs. Feeding your baby when your baby needs to be fed is the key to making this work.

If one breast is allowed to ‘dry up’ it will be smaller than the breast that continues to make milk. This will cause some lopsidedness but once weaning occurs, your breasts will even up again.