Most breastfeeding moms are familiar with this common side-effect of nursing a baby: boobs that are a little, ahem, unbalanced. Sometimes lopsided breasts occur when one boob produces more than the other, or maybe your baby simply prefers Leftie over Rightie (or vice versa), for mysterious baby reasons. Zoe Hendrix, a 27-year-old Australian mom whose daughter is about nine months old, is totally owning the lopsided knockers look. She recently shared this bikini-top selfie on Instagram with the caption, “Milk jugs gone uneven.” The Australian reality TV star, posting under the #normalizebreastfeeding hashtag, noticed that she was getting a lot of stares at the pool that day, and wondered if her apple-and-orange situation (which is really more more like a grapefruit and a melon!) was the reason. (Truth: It’s probably because she’s rocking a hot-pink bikini, regardless of how pregnancy and nursing have changed her boobs.)
Asymmetry throughout the human body is pretty normal, and breasts are no exception. Most women will naturally have more milk ducts and alveoli in one boob than in the other. (Apparently, it’s usually your left breast that has more functioning milk ducts than your right one does, but everybody’s different.)
When a baby develops a preference for one side, it could be because the milk flow or letdown is faster in one breast than the other, and your infant gets picky, expressing his opinion with fussiness or refusing to latch. (Some babies like a slow flow, some babies want to guzzle.) Once your little one gets more comfortable feeding successfully on his preferred side, the supply-and-demand nature of breastfeeding can exacerbate the disparity between how much each boob produces, causing a visible difference in cup size. Your milk could even dry up in the non-preferred boob.
Other possible causes of lopsided breasts include an infant who’s in pain from an ear infection in one ear, or from getting vaccination shots on one side of his body; a mom’s nipple differences (for example, one flat or inverted nipple); or a breast infection in one breast (which can make that side's milk taste a little different). You could also, accidentally, be offering one breast more frequently than the other, just out of habit. (Maybe you’re trying to multitask and subconsciously keeping your dominant hand free so you can drink your coffee, pour milk into your toddler’s cereal bowl, or use your phone.)
So, what can you do? Having lopsided knockers is really nothing to worry about, because you can safely nourish a baby using just one breast, no problem. Some experts warn that doing so can cause flat head or torticollis—when a baby develops an uneven noggin and some neck tension from always having his head turned in the same direction. Switching sides while breastfeeding helps alleviate the chances of this happening, but so do other simple measures, like baby-wearing and doing lots of tummy time.
If the difference in cup size is bothering you, you could make sure your baby always begins a nursing session on the non-preferred boob, when he’s hungriest and nursing more ravenously. Or offer him the non-favoured breast when he first wakes up and is sleepy, or while you’re walking around, bouncing or swaying—using motion as distraction. There’s also the ol’ bait-and-switch, when you start your infant on her favourite side, and then quickly and smoothly move her over to the other boob without changing her position too much (for example, going from the cradle hold to the football hold).
If you have a breast pump, try expressing and collecting milk from The Rejected Boob (a great band name, BTW) for five or ten minutes while (or after) your baby nurses on the preferred boob, to make sure your supply doesn’t dwindle. There’s also something called “block feeding,” which is when you keep your baby on the same side for several nursing sessions in a row, without switching sides mid-feed as you normally would. But be careful not to cause engorgement, blocked ducts or mastitis in the over-achieving boob while you’re trying to convince your baby to love Leftie (or Rightie) again.