Menstrual bleeding patterns in pre- and perimenopausal women: a population-based prospective diary study.

Background: To investigate natural menstrual bleeding patterns in pre- and perimenopausal women, a prospective observational population study was carried out.

Methods: A total of 1616 (80.8%) of a population-based sample of 2000 Danish women aged 45-54 years answered an initial questionnaire.