Objectives: To determine whether the onset and duration of being overweight or obese are associated with symptoms of urinary incontinence.
Design: Nationally representative cohort study.
Subjects: A total of 1201 women followed-up since their birth in 1946 and annually from 48 to 54 years.
Measurements: The body mass index (BMI) at the age of 20, 26, 36 and 43, and symptoms of stress, urge and severe incontinence at seven consecutive years from age 48 to 54.
Results: In each year from age 48 to 54, almost half (46-49%) reported symptoms of stress incontinence, urge incontinence rose from 22 to 25% and severe incontinence from 8 to 11%. At the age of 20, 26, 36 and 43, BMI was positively associated with stress symptoms and severe incontinence in midlife. BMI transition was found to have accumulation effects on symptoms of severe incontinence; women who were overweight/obese since age 20 years were more likely to report severe incontinence than women whose BMI remained below 25 kg/m(2) (odds ratio (95% confidence interval): 2.30 (1.36-3.93)) or who became overweight or obese at 43 years (1.85 (0.97-3.51)). These relationships existed beyond the effects of aging, childhood enuresis, kidney infection, childbirth characteristics, menopause, educational attainment, general practitioner consultations and smoking status. BMI was not associated with symptoms of urge incontinence.
Conclusions: Across adult life, higher BMI for women was linked with subsequent symptoms of stress and severe incontinence in midlife; those who were overweight or obese since early in adult life more than doubled their risk of severe incontinence. Women, and especially young women, should be encouraged to keep their weight in a normal range throughout adult life.