A group of University of Kentucky researchers led by plastic surgeon Brian Rinker have determined that smoking is what causes sagging breasts, not breastfeeding. Their information was drawn from a study of British breast lift and breast augmentation patients, and the results were presented to the American Society of Plastic Surgeons earlier this week.

Rinker said that his study was sparked by the fact that, "A lot of times, if a woman comes in for a breast lift or a breast augmentation, she'll say, 'I want to fix what breastfeeding did to my breasts'." He and is team subsequently interviewed 132 women, average age 39 years, from 1998 to 2006. Ninety-three percent of them had been pregnant at least once, and fifty-eight percent had breastfed at least one of their children.

The patients' complete medical histories were then reviewed, including documentation of BMI (body-mass index) bra-cup sizes pre- and post- pregnancy, and whether or not they smoked. No differences in breast ptosis (that's the technical term for "sagging of the breast") were noted in those women who breastfed when compared with those who did not.

However, several other factors were discovered to affect breast sagging, and the biggest contributor was smoking. As Rinker explained, "Smoking breaks down a protein in the skin called elastin, which gives youthful skin its elastic appearance and supports the breast... so it would make sense that it would have an adverse effect on the breasts."

What does this mean for women? Well, it's already known that you shouldn't smoke while pregnant or breastfeeding, but if you want to keep your firm, supple breasts long into your life? Don't smoke at all.