Stress incontinence is the most common form of urinary incontinence. Bladder control is lost and urine leaks when the pressure on the bladder is increased. Common events that increase the pressure on the bladder (mostly through increased pressure from the abdominal wall) are laughing, sneezing, lifting of objects and jumping.

Different physical changes resulting from pregnancy, childbirth, and menopause increase the occurrence of stress incontinence.
Stress incontinence is mostly caused by weakened muscles in and around the pelvic floor, weakened bladder neck support, and due to the fact that internal organs sag, which results in increased pressure on the bladder, while the pelvic floor muscle also weaken (or are torn to a high degree due to sometimes frequent - childbirth).

As a result the bladder itself may move downwards moving closer to the vagina (see figure above). Stress incontinence also occurs if the pelvic floor muscles weaken.

However, the cause of stress incontinence is not only limited to muscular problems; hormonal changes (temporarily around one week prior to the period and after menopause) also contribute to stress incontinence as the muscular tension suffers from lower estrogen levels. Main treatment options are the Kegel exercise and surgery (Urinary Incontinence Consensus Conference, 1998).