Variation in antimüllerian hormone concentration during the menstrual cycle may change the clinical classification of the ovarian response.

OBJECTIVE To assess the variability of antimüllerian hormone (AMH) concentrations in women with "adequate ovarian reserve" during unstimulated menstrual cycles and to determine the impact on clinical classifications. DESIGN Pilot cohort study. SETTING Private fertility clinic. PATIENT(S) Twelve consecutive women (aged 29 to 43 years) referred to a fertility service, with AMH measurements repeated throughout unstimulated cycle, and who had at least one AMH measurement indicating "adequate ovarian reserve." INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) AMH concentrations assessed in 82 serum samples from 12 women compared against the published cutoffs for reduced ovarian reserve and for risk of excessive response to ovarian stimulation. RESULT(S) Over half the women (7 of 12) were reclassified as a result of testing AMH concentrations at different phases of the menstrual cycle. Over one-third (4 or 5 of 12) crossed a cutoff for reduced ovarian reserve; 2 of 12 crossed cutoffs predicting hyperstimulation. There was a statistically significant change in AMH concentration according to the day of the cycle, with a negative trend of the median AMH concentration from the follicular to luteal phase. The maximum change in median AMH concentration over cycle was 7.9 pmol/L, and the mean difference between the maximum and minimum AMH was 6.7 pmol/L. CONCLUSION(S) In this pilot study, the AMH concentration varied during menstrual cycle, and the clinical classification of the ovarian response was altered.