A 15-year French study has concluded that bras provide no long-term benefits for breasts –– and might actually increase sagginess.
Professor Jean-Denis Rouillon, a professor at the University of Franche-Comte in Besancon, examined and measured more than 300 women's breasts when they were 18 and 35, taking into account how wearing bras affected them.
"Medically, physiologically, anatomically, the breast does not benefit from being deprived of gravity," Professor Rouillon told wesbite France Info.
He found that the nipples of women who didn't wear bras lifted and that wearing a bra from puberty meant the breasts did not develop strength, which could accelerate sagging.
But Dr Deirdre McGhee, a sports physiotherapist and researcher from Breast Research Australia at the University of Wollongong, told ninemsn that only studying women up to the age of 35 is pointless.
"It's only from 35 on that the skin decreases in its elasticity and the breasts tend to sag more after that because the skin is the primary support of the breast," she said.
Dr McGhee said women should wear bras for immediate comfort, not for long-term gains.
"Bra manufacturers do promote that bras can reduce long-term sagging, but there is no evidence to prove that," she said.
"We say women should wear bras during physical activity to minimise movement and limit breast discomfort and embarrassment. For everyday, if you wear a bra and your breasts are lifted, then the bra helps you to maintain a better posture, particularly in large-breasted women."
She said any long-term study into whether bras can alter the shape of breasts would have to take into account race, breast size, whether the participants had children and the amount of physical activity they did.
"If you didn't standardise for all of these factors, then you couldn't make this statement," Dr McGhee said.
Professor Rouillon told France Info there's no point in women burning their bras if they've worn them long-term.
The study did not mention breast size and Professor Rouillon also cautioned that the study sample may not be representative of the entire population.