Reproductive and hormonal risk factors for urinary incontinence in later life: a review of the clinical and epidemiologic literature.

OBJECTIVES: To review and integrate the current literature on the role of reproductive factors in the development of urinary incontinence in later life.
DESIGN: An extensive literature review using Medline and Science Citation Index for the period 1966 through 1997 was undertaken to identify published studies of the association between parturition events, hysterectomy, menopause, estrogen therapy, and later urinary incontinence.
RESULTS: Vaginal delivery is an established risk factor for both transient postpartum incontinence and the development of incontinence in later life. Several studies have found evidence of nerve and muscle damage that provide a physiologic basis for this association. Prospective studies of incontinence after hysterectomy have generally found no increased risk in the first few years. In contrast, cross-sectional epidemiologic studies have consistently found an increased risk many years after hysterectomy. Although menopause is often considered a risk factor for urinary incontinence, epidemiological studies have generally not found an increase in the prevalence of incontinence in the perimenopausal period. Oral estrogen replacement therapy seems to have little short-term clinical benefit in regard to incontinence and is associated consistently with increased risk of incontinence in women aged 60 years and older in epidemiologic studies.
CONCLUSIONS: This review provides a framework for further investigation of the complex relationships between reproductive risk factors and urinary incontinence. Integration of physiologic, clinical, and epidemiologic studies is needed to address the compelling health care issue of urinary incontinence. Suggestions are made for further areas of research.