Antimüllerian Hormone, Antral Follicle Count and Ovarian Volume Predict Menstrual Cycle Length in Healthy Women

Objective: Although menstrual cycle length is one of the main concerns of women and may have important health consequences, little is known about its predictors. The aim of this study was to identify predictors of menstrual cycle length variability in healthy women.

Design: Prospective cross-sectional study.

Patients: Two hundred healthy women aged 21-45.

Measurements: A questionnaire was administered to determine lifestyle factors. Ovarian parameters, metabolic parameters, pituitary hormones, sex steroids and antimüllerian hormone (AMH) were measured.

Results: Women with long (≥35 days) and normal (25-34 days) menstrual cycles had >5-fold and >2-fold higher serum AMH levels, respectively, compared to those with short cycles (<25 days). Menstrual cycle length was associated with age but not lifestyle factors. Only one factor group (AMH, antral follicle count [AFC], ovarian volume, testosterone and LH) was significantly associated with menstrual cycle length. Within this factor group, only the ovarian parameters (AMH, AFC, ovarian volume) predicted menstrual cycle length. Each SD increase in AMH (32·9 pmol/l) and ovarian volume (2·29 cm(3) ) was associated with 2·80-fold (95% CI: 1·67-4·69) and 1·62-fold (95% CI: 1·08-2·43) increased risks, respectively, for longer menstrual cycles.

Conclusions: AMH, AFC and ovarian volume are positively associated with menstrual cycle length in healthy women. Our identification of AMH as an independent predictor of menstrual cycle length puts forth a new notion of utilizing menstrual cycle length to predict possible AMH-dependent/-associated outcomes. In addition, this novel relationship may facilitate the interpretation of AMH levels and its clinico-pathological significance across different centres.