Highlights:• We show that Chinese women have higher AMH levels than the European counterparts before age of 25, but after the age of 25 this is reversed and Chinese women have lower AMH levels.• The disparity between the two populations widens with increasing age.Research Question: Chinese women are known to have an earlier age at natural menopause than their European counterparts, whether they also have a lower functional ovarian reserve is unknown. This study was designed to assess whether there are ethnic differences in Anti-Müllerian Hormone (AMH) in women of reproductive age.Design: Women with regular menstrual cycles, not on hormonal contraception or with any medical history of note, were recruited to provide a day 2-5 early follicular sample in China and Europe. AMH was determined using the Roche Elecsys assay.AMH decline was modelled with a linear, quadratic and quadratic with interaction on age equations to assess the impact of ethnicity.Results: 887 European and 461 Chinese women participated in the study. Despite the Chinese population being slightly younger 34.1±8.4 years than their European counterparts 34.8±8.9 years, their median AMH was lower 1.87 (IQR 0.28, 3.64) as compared to 2.11 (IQR 0.73, 3.96), with evidence of increasing discordance from age 25 years. In all regression models of the AMH age-related decline, there was evidence of a difference between Chinese and European women. Whilst AMH was 28.1% (95% CI; 18.2, 36.7%) lower in the Chinese population at age 30, this decline increased to 79.4% (95% CI; 75.4, 82.9%) at age 45.Conclusions: There were independent effects of age and ethnicity on serum AMH concentrations, with Chinese women having a substantially lower AMH in adult life than their European counterparts from age 25 onwards.

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