There are two basic causes for SUI. Most commonly, SUI is caused by weakening in the pelvic floor. The muscles of the pelvic floor support the organs of the lower urinary tract, including the urethra (the tube from the bladder through which urine exist the body). A strong pelvic floor keeps the urethra tightly sealed until it’s time to urinate. A weakened pelvic floor cannot hold the urethra in its correct position, so any movement from the diaphragm that puts pressure on the bladder (such as a sneeze) may cause the urethra to lose its seal and allow urine to escape.

Another cause of SUI is intrinsic sphincter deficiency (ISD). The sphincter muscles hold the urethra closed until it’s time to urinate, when they relax their grip and allow urine to flow. In women with ISD, the sphincter muscles don’t function as they should, which can cause urine to leak during movements that put pressure on the bladder. Stress urinary incontinence caused by ISD may be treated with injectable material.

Stress urinary incontinence is not necessarily a natural part of the aging process. It affects women of all ages. In women, SUI is commonly caused by:

There are also temporary, reversible causes for urinary incontinence, including: