It’s common for breastfeeding mothers to notice that one of their breasts makes more milk than the other.
For example, they might notice they can consistently express more breast milk from one breast than from the other, or their baby prefers feeding on one breast, or their breasts are different sizes.
This might make some mothers worry that one of their breasts isn’t working well or their supply isn’t enough for their babies to get enough milk.
The good news is that, most of the time, it’s normal for one breast to work better than the other, and it’s nothing to worry about.
5 reasons why one breast works better than the other
Let’s explore the reasons why only one breast works when breastfeeding.
Only One Breast Works #1: It could be normal
It’s normal for one side to have more milk production than the other, and typically have a faster flow.
Often, this is the breast your baby prefers. Some babies might struggle with the faster flowing side and prefer the calmer breast.
Some mothers might have a nipple that’s a different shape or size (e.g. inverted or flat) that makes that breast more difficult for a baby to attach and stay latched to.
You might find it useful to read our article Flat or Inverted Nipples? Try These 3 Helpful Tips.
Only One Breast Works #2: Mastitis
In cases of mastitis, many mothers notice a temporary drop in milk production in the affected breast.
At the same time, the baby might not feed as well from that breast due to the milk supply drop or because the breast milk tastes saltier.
Most of the time, however, a baby can still remove milk from the affected breast better than a breast pump can.
When the mastitis settles down, it’s common for babies to want to feed more frequently.
This increased feeding is usually enough to boost milk production in the affected breast, bringing it back to where it was before the mastitis occurred.
Only One Breast Works #3: Baby favors one breast
Most babies prefer to feed from one breast rather than both breasts, to some degree.
This could be because one breast produces more breast milk than the other breast, or because the baby’s preference is the faster flow from one breast.
Occasionally the feeding position on the less preferred breast can be a result of the baby feeling discomfort in his body he obviously can’t communicate.
Only One Breast Works #4: Mother prefers feeding on one breast
Without realizing it, a mother might show breast preference, preferring to feed her baby from just one breast rather than alternate breasts.
She might feed first from the preferred side at more feeds or offer that breast for top-ups.
It night be because she feels more confident and comfortable with positioning and attaching her baby than with the less preferred breast.
A mother’s right 0r left-handedness might also make it easier for her to attach on her right or left side, depending on which hand is her dominant one.
Only One Breast Works #5: Breast surgery
If a mother has had previous breast surgery, the surgery might have affected the milk-making ability of one breast more than the other.
For example, more milk ducts and/or glandular tissue could have been removed from one breast than the other during breast reduction or breast cancer surgery.
Similarly, nerve damage, which affects the let-down reflex and milk flow, might have occurred more in one breast than the other.
How can I get my breast milk supply back up?
If your baby is nursing according to his individual need, it’s OK to do nothing in particular, other than to alternate the breast from which breastfeeds begin and to offer both the breasts.
This is because each breast will then respond to the demands placed upon it, and your milk supply will increase.
If significantly more breast milk is removed from one breast (e.g. because the baby has a strong preference for it), then that breast will make more milk.
If significantly less milk is removed from the other breast, the milk supply will decrease, but the lack of milk produced by this breast will be made up for by the other breast.
If you’d like to try to even up the supply in each of your breasts, it can help to:
- Nurse on the least preferred side first at feeds. This is because a baby typically feeds most vigorously, and takes more milk from the breast he feeds from first. Doing this could increase your risk of engorgement, blocked ducts, or mastitis, so be careful to monitor the preferred breast for lumps
- Offer the least preferred side 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.
When following the these tips, most mothers notice their breasts will even out within a few days or so.
Most moms try these tips for a short time, until they get the results they are after. Other mothers continue to follow them long-term.
Why is my baby refusing one breast?
If your baby typically feeds well from both breasts and then suddenly starts breastfeeding from one side only, this might be due to:
Having a vaccination might make one of your baby’s arms sore, so a particular breastfeeding position could 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 might prefer to feed on one side. If you think your baby might have an ear infection or other illness, see a doctor.
If your newborn prefers feeding from one side, see a doctor to check for any injury that might have occurred during birth and is causing the baby to feel pain in certain breastfeeding positions.
It might also be beneficial to visit a paediatric osteotherapist, who will check your baby from head to toe to see if any body work is required.
A blocked nostril
If your baby is nursing on only one side it could be he has a stuffy nose.
We all have mucous and babies sometimes struggle to clear it themselves, which makes it difficult to nurse.
What can I do if my baby will only feed from one breast?
If your baby is very fussy and will only feed from one breast, here are some things to think about:
- Breastfeed in a different position. For example, if he’s 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 to breastfeed him in the football hold for the right breast, as he’d 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 so he’s facing you with his head just above your breasts is a good position to allow him to do this
- Try breastfeeding 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, might benefit from an appointment with a trained musculoskeletal therapist, such as an osteopath, physio, or chiropractor who specializes in babies.
- If your baby is completely refusing one side, you could express from that side as often as he breastfeeds from the other side. This will help keep up your supply until he’s back feeding from both breasts.
One breast is not producing milk any more
It’s possible for one breast to make all the milk a baby needs and for a baby to breastfeed only from one side.
Breastfeeding your baby on the basis of supply and demand (whenever your baby needs to be fed) is the key to making enough milk.
If one breast is allowed to ‘dry up’, it will be smaller than the breast that continues to make milk.
This will cause uneven breasts; once weaning occurs, though, most women’s breasts will even up again.
If you’re having difficulty with your breastfeeding, or your baby prefers a particular side, reach out to a lactation consultant or the Australian Breastfeeding Association.
Getting the right support early – especially in the first few weeks while you are both still trying to get the hang of breastfeeding – can make the world of difference.