Assymetrical breasts are fairly common, but when you're breastfeeding, the differences between your boobs can be even more obvious. I remember one breast always feeling heavier than the other, and I could often pump more breast milk out of one than the other. For some of you, your baby may prefer one breast over the other or your let-down may differ between the two, leaving you to wonder why you have slow let-down on one side, but not the other.
When you think about why a slow or fast let-down happens, it makes sense as to why it can be different between your breasts. A fast let-down is often the cause of an oversupply of milk, but a slow let-down can be caused by a variety of things like stress, anxiety, and pain according to KellyMom. And your breasts? They don't always produce the same amount of milk on both sides.
KellyMom noted in a separate article that it is very common for women to find that each of their breasts produces a different amount of milk. One breast may have a larger output when pumping than the other, or you may notice that one leaks more often. Because your breasts may have a difference in volume and production, they can have a difference in let-down, causing you to experience a slow let-down on only one side. If one breast seems to always produce more, the let-down may be faster due to the volume of milk.
Not only could your slow let-down just be slow in comparison to the let-down on the other side, but if you are feeling stressed or anxious about the amount one breast is producing, it can affect your let-down and cause it to decrease. La Leche League International also noted that because the let-down reflex correlates with your milk production, you may find that a slow let-down is happening with a breast that isn't releasing as much milk as the other. This can happen if you are constantly switching between breasts rather than letting your child feed from one breast until it is empty
In short, if the slow let-down doesn't bother you or your baby, it's not a huge deal. You may find that your child is fussy when feeding from that breast as they wait for the milk to release, but by massaging the breast beforehand or trying other techniques to help your milk let-down, you can help your little one.