At some point as you age, your breasts will answer the call of gravity as your ligaments stretch and your skin loses elasticity. If you're a smoker or if you lose or gain large amounts of weight in a short period of time, you may find your breasts sagging sooner than later. While you can't prevent sagging completely without the aid of plastic surgery, you can slow the process if you know the reasons that breasts start to sag. Pregnancy and Breastfeeding Pregnancy and breastfeeding themselves don't necessarily lead to sagging breasts according to a study published by the American Society of Plastic Surgeons in 2007. Women who experience sagging or deflated breasts after pregnancy or breastfeeding often do so because of rapid weight gain and loss. This can be mitigated by avoiding excess weight gain during pregnancy. Many women incorrectly believe breastfeeding will lead to breast sagging. The truth is that your breasts are more likely to sag if you don't breastfeed according to the study, because the breast tissue and milk glands shrink more dramatically in women who do not breastfeed, which causes a deflated, saggy appearance. Age A few factors come together to cause sagging breasts as you age. Skin thins out and loses its elasticity, according to the Mayo Clinic. Estrogen production decreases, which causes breast tissue to shrink. These changes leave your breasts looking both deflated and lower. When your body produces less estrogen, it also produces less collagen. Collagen is necessary to keep your breast tissue and skin firm. Smoking also reduces this collagen production, according to the Mayo Clinic. Finally, the ligaments that hold your breasts in place weaken and stretch with time. Weight Loss or Gain Women who gain weight typically also gain in their breasts. As your breasts gain volume, they become heavier and are then more susceptible to the effects of gravity, according to Ayurvedic Care. Heavy breasts also place more strain on ligaments and connective tissues that hold the breasts up. If you then lose wight, your breasts lose volume but the connective tissues remain stretched. If you lose weight quickly, your skin may take more time to shrink, leaving you with sagging breasts, which may or may not be permanent. Source: livestrong.com