Thyroid hormones and menstrual cycle function in a longitudinal cohort of premenopausal women

Background Previous studies have reported that hyperthyroid and hypothyroid women experience menstrual irregularities more often compared with euthyroid women, but reasons for this are not well understood and studies on thyroid hormones among euthyroid women are lacking. In a prospective cohort study of euthyroid women, this study characterized the relationship between thyroid hormone concentrations and prospectively-collected menstrual function outcomes.