This article was first published in The Skeptical Inquirer.
Humans are the only animals with permanent breasts. In other mammalian species, breasts grow with pregnancy and shrink back down following lactation. As well as being pleasant to look at, our permanently enlarged bosoms function to give bra manufacturers a career. Estimates typically place the percentage of women wearing bras upward of 90 percent, depending on the country, age, and survey methods. Are those in the braless minority putting themselves at risk of sagging mammilla?
Surprisingly, this topic has not been studied as much as I expected. This is possibly due to most internet sources on the matter referring to a seemingly definitive fifteen-year study of 320 women by sports science expert Jean-Denis Rouillon at the University of Besançon in France. Rouillon claims to have studied hundreds of women over a decade and a half, recording their bra-wearing habits and using calipers and a ruler to measure changes in their breast presentation. In a radio interview with France Radio that everyone from MedicalNewsToday to Reuters to The New York Times reported on, Rouillon shared that “women who never wore bras had nipples on average seven millimeters higher in relation to their shoulders each year than regular bra users.”
The only problem is that Rouillon’s research was never published, and reporting news agencies can’t even agree on what university he did the work at. Without seeing Rouillon’s methods, calculations, demographic information, and how he sought to eliminate bias, we really cannot conclude anything from his claims.
Published studies have found that breast size and age are the primary predisposing factors to breast ptosis (the medical term for sagging). One study of eleven young women published in 1990 found that after three months of wearing a “well-fitted” bra, their breasts hung down more.
Unfortunately, what we need to answer this question definitively is more research. Until then, I’d encourage you to choose your bra status with comfort in mind, as it seems many women did during the pandemic by ditching their bras.