If you have stress incontinence, you may experience urine leakage when you:

• Cough
• Sneeze
• Laugh
• Stand up
• Get out of a car
• Lift something heavy
• Exercise
• Have sex

You may not experience incontinence every time you do one of these things, but any pressure-increasing activity can make you more vulnerable to unintentional urine loss, particularly when your bladder is full.

Female pelvic floor muscles

Stress incontinence occurs when the muscles and other tissues that support the bladder (pelvic floor muscles) and the muscles that regulate the release of urine (urinary sphincter) weaken.

The bladder expands as it fills with urine. Normally, valve-like muscles in the urethra — the short tube that carries urine out of your body — stay closed as the bladder expands, preventing urine leakage until you reach a bathroom. But when those muscles weaken, anything that exerts force on the abdominal and pelvic muscles — sneezing, bending over, lifting, laughing hard, for instance — can put pressure on your bladder and cause urine leakage.

Your pelvic floor muscles and urinary sphincter may lose strength because of:

• Childbirth. In women, poor function of pelvic floor muscles or the sphincter may occur because of tissue or nerve damage during delivery of a child. Stress incontinence from this damage may begin soon after delivery or occur years later.
• Prostate surgery. In men, the most common factor leading to stress incontinence is the surgical removal of the prostate gland (prostatectomy) to treat prostate cancer. Because the sphincter lies directly below the prostate gland and encircles the urethra, a prostatectomy may result in a weakened sphincter.

Contributing factors

Other factors that may worsen stress incontinence include:

• Illnesses that cause chronic coughing or sneezing
• Obesity
• Smoking, which can cause frequent coughing
• High-impact activities, such as running and jumping, over many years

Factors that increase the risk of developing stress incontinence include:

• Age. Although stress incontinence isn't a normal part of aging, physical changes associated with aging, such as the weakening of muscles, may make you more susceptible to stress incontinence. However, occasional stress incontinence can occur at any age.
• Type of childbirth delivery. Women who've had a vaginal delivery are more likely to develop urinary incontinence than women who've delivered via a cesarean section. Women who've had a forceps delivery to more rapidly deliver a healthy baby may also have a greater risk of stress incontinence. Women who've had a vacuum-assisted delivery don't appear to have a higher risk for stress incontinence.
• Body weight. People who are overweight or obese have a much higher risk of stress incontinence. Excess weight increases pressure on the abdominal and pelvic organs.
• Previous pelvic surgery. Hysterectomy in women and particularly surgery for prostate cancer in men can alter the function and support of the bladder and urethra, making it much more likely for a person to develop stress incontinence.

Complications of stress incontinence may include:

• Personal distress. If you experience stress incontinence with your daily activities, you may feel embarrassed and distressed by the condition. It can disrupt your work, social activities, relationships and even your sex life. Some people are embarrassed that they need pads or incontinence garments.
• Mixed urinary incontinence. Mixed incontinence is common and means that you have both stress incontinence and urge incontinence — the loss of urine resulting from an involuntary contraction of bladder muscles (overactive bladder).
• Skin rash or irritation. Skin that is constantly in contact with urine is likely to be irritated or sore and can break down. This happens with severe incontinence if you don't take precautions, such as using moisture barriers or incontinence pads.