Human bodies are not symmetrical, and both sides are not exactly the same. But you don’t usually realize this until you become a mother and start producing breastmilk. The milk supply of each breast is regulated by a type of hormone called FIL, Feedback Inhibitor in Lactation. This hormone responds to demand and supply. That is to say, if the baby suckles a lot and takes out all the FIL, the mammary gland gets the message: must produce more milk! If, on the other hand, the FIL remains inside the breast, the body responds by making less breastmilk.

Each baby also has their own preferences, and they show them. Almost all babies, without mothers even noticing it, nurse more from one breast side than from the other. And this is where the “chicken or egg” phenomenon begins:

Does a baby feed more from a certain breast side because this breast has more milk and they like it better? Or because a baby feeds more from one breast side, this makes more supply, and therefore, the baby prefers that side?

Whatever the cause, it always leads to differences in the size of the two breast sides. One breast is much larger than the other, and it is often so obvious that it can be seen easily. And that’s where questions arise:

Is it bad to have different-sized breasts?

No. This is just an aesthetic issue. It is understandable that you may feel worried or upset about this situation, but it is much more common than you think. Many mothers experience this. In fact, it’s a pretty common joke in the breastfeeding world. There are many cartoons that illustrate this situation, and this will undoubtedly resonate with you.

Is there anything I can do to make the two breasts equal in size?

You can try to offer the smaller breast side more often to your baby. For example, you can try to always offer that breast first, but your baby needs to accept, and that doesn’t always happen. There are mothers who choose to use a breast pump to stimulate breastmilk supply on the smaller side. But if you do this, you have to be careful not to get mastitis as a consequence because if you stimulate and increase milk supply, but the baby does not want to suckle from that breast, there is a risk that the milk accumulates.

If my baby only feeds from one breast, will she get enough?

Of course! One breast is perfectly capable of producing all the breastmilk a baby needs. There are mothers who breastfeed for months and years from one side without any problems at all.

I have much more milk in one breast side than in the other

Then, the two breasts usually show a big difference in size. And you usually notice this when you express milk by hand or with a breast pump. This is when you can observe and see the difference in output between the two breasts. This noticeable difference is very common, and almost all women experience it during their breastfeeding journey, but it does not impact the weight gain of their babies.

And just as a curiosity, in other mammals, something similar happens, and the mammary gland in the upper part of the thorax produces less than the lower ones.

When breastfeeding ends, will my breasts return to normal?

The asymmetry in size will be maintained over time, but after weaning and stopping breastfeeding, everything gradually returns to normal, and the asymmetry will not be so visible anymore.