Everything You Need to Know About 'Pitties,' a Rare Armpit Armpit Swelling That Happens from Breastfeeding

The human goes through some miraculous changes when growing and nurturing babies–but there's one we never expected. Here's everything you need to know about why breast tissue can swell up in your armpits.

Close-Up Of Woman With Arms Raised and a milk bottle emoji overlayed on top
Photo: Illustration by Francesca Spatola; Getty Images (2)

The human body is amazing. The changes that come with pregnancy and breastfeeding are both inspiring and unbelievable, and anyone who has experienced them deserves a serious round of applause. Though many of these changes are well-known (breast milk changing to meet the needs of the baby, ligaments loosening and bones spreading to allow for the passage of the baby through the birth canal, a body that is able to nurture and grow a baby from conception into toddlerhood and beyond), they are still truly incredible.

But recently many of us learned about the existence of something new, something we hadn't seen before, something that stopped even seasoned breastfeeders in their tracks. What was this shocking discovery? Pitties.

An anonymous and since-deleted photo posted on Twitter showed an image of a person with their arm raised, homing in on two large lumps in their armpit. Turns out, the lumps were breast tissue that had become engorged with milk, hence the name "pitties."

What Are Pitties?

As odd as this phenomena may seem, it's not unusual, which should surprise no one whose body has ever confused them by doing something unexpected while pregnant or breastfeeding. Mammary tissue is not only found in the breasts. There's a structure called the Tail of Spence that extends beyond the breast itself and into the armpit. Since it's connected to the main milk-producing tissues in the breast it can become engorged.

However, unlike engorgement of the breasts in which the breast itself swells and becomes tight, engorgement in the armpit is a little different. "The engorgement that occurs looks like egg-shaped lumps under the armpits, " explains Colorado-based Andrea Tran, RN, BSN, MA, IBCLC, and expert behind the Breastfeeding Confidential website.

Do Pitties Go Away?

Engorgement in the armpits most frequently occurs early in breastfeeding, while milk supply is being established. "It is breast tissue that doesn’t drain well and for that reason, the engorgement is primarily experienced when the milk first comes in. Because of the poor drainage in that area those milk-producing cells stop producing," explains Tran.

Engorgement here should be treated the same way as engorged breasts–cool compresses and patience–and should resolve in 24 to 48 hours.

All things considered, milk being created in your armpit is probably one of the least strange things that can happen during breastfeeding, but if you're not expecting it, talk about a surprise. Luckily, it's harmless and resolves easily, so there's no need to freak out if you wake up one morning with bulging pits.

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