Effects of Estrogen with and without Progestin on Urinary Incontinence

February 2005

Findings Summary

WHI researchers continue to analyze the data from participants in the Estrogen Plus Progestin (E+P) and Estrogen-Alone trials to learn more about the effects of hormones on postmenopausal women’s health. An analysis of the effects of the hormones, conjugated equine estrogen combined with progestin or alone, on urinary incontinence (UI) was published in the February 23, 2005 issue of the Journal of the American Medical Association (JAMA).
Urinary incontinence refers to an uncontrolled leaking of urine or loss of bladder control. It can range from a very small amount of leaking that is barely noticeable to soaking of clothing. There are several different types of UI:
  • Stress incontinence, the most common type, is the leaking of urine when a person coughs, laughs, sneezes, lifts, stands up, or exercises.
  • Urge incontinence occurs when a person feels the need to go to the bathroom but cannot get to the toilet fast enough to prevent urine from leaking.
  • Mixed incontinence occurs in people who have both types of UI.
The female hormone, estrogen, can affect the tissues and muscles in the pelvic area. Therefore, the WHI researchers wanted to look at the effects of hormones on the development of UI in women who were “continent” when they joined the WHI (they had not leaked urine in the past year). In addition, estrogen medications have sometimes been prescribed for women with UI, so the researchers also analyzed the effects of hormones in women who, when they joined the WHI, reported some UI in the past year. These effects were studied separately for participants in the E+P trial, who had not had a hysterectomy before joining the WHI, and those in the Estrogen-Alone trial, who had a hysterectomy before joining.
Women who did not have UI when they joined the WHI hormone trials had an increased risk of developing any type of UI after 1 year if they were in the active hormone group compared to the placebo group. This risk was 39% higher for women taking active hormones in the E+P trial compared to those taking placebo. The risk was 52% higher for women taking active hormones in the Estrogen-Alone trial compared to placebo. Of all the types of UI, the risk was highest for developing stress incontinence, followed by mixed incontinence.
Among women who reported some UI when they joined the WHI, the active hormones in both the E+P and Estrogen-Alone trials worsened both the frequency and amount of UI after one year, compared to placebo. In addition, women taking the active hormones were more likely than women taking placebo to report that the UI bothered or disturbed them and that it limited their daily activities.
The researchers concluded that postmenopausal hormone therapy with either conjugated equine estrogen combined with progestin or alone should not be prescribed to women to prevent or treat urinary incontinence.