Antimüllerian hormone levels and numbers and sizes of antral follicles in regularly menstruating women of reproductive age referenced to true ovulation day

ObjectiveTo assess menstrual cycle antimüllerian hormone (AMH) levels in reproductive age women and which/how many follicles substantially produce AMH.DesignProspective study of menstruating women using mixed-effects models to analyze AMH variability and correlation of follicle counts/size classes to AMH levels.SettingClinic.Patient(s)Regular menstruating women with ovulatory cycles (n = 40, aged 18-37 years) and no known subfertility.Intervention(s)Women collected daily urine samples and visited the study center for blood samples/transvaginal ultrasound during one complete menstrual cycle (visits were every 2 days; daily from follicle size >16 mm until postovulation).Main Outcome Measure(s)AMH levels throughout the menstrual cycle, correlated with antral follicles as observed by ultrasound and identification of follicles producing AMH.ResultsOf all antral follicles visible by high-resolution ultrasound, AMH is produced substantially only by follicles up to 7 mm in diameter. For women with basal AMH >1 ng/mL, mean AMH concentrations vary across ovulatory menstrual cycles, showing a statistically significant decrease from −5 to 2 days after objective ovulation; significantly lower mean luteal AMH levels (−7.59% to mean follicular AMH) are detected. The number of antral follicles can be estimated from AMH (ng/mL) levels using the modified Beckman Coulter Generation II AMH assay for any day of the follicular phase.Conclusion(s)AMH concentrations vary across ovulatory menstrual cycles, showing a significant periovulatory decrease. The number of small antral follicles can be estimated from preovulatory AMH levels with relevance for patient management.Clinical Trial Registration NumberNCT01802060.