Stress urinary incontinence, the most prevalent form of incontinence among women, affects an estimated 15 million adult women in the U.S. With this type, urine leaks due to weakened pelvic floor muscles and tissues. It can happen when pressure on your bladder increases - such as when you exercise, laugh, sneeze, or cough. Pregnancy and childbirth can stretch and weaken a woman's pelvic floor muscles.