AMH and precocious puberty: As for the mean chronological age of cases, there was no significant association between precocious puberty and the level of serum AMH in the subgroup with the mean age of cases < 8 (P = 0.87) and the subgroup with the mean age of cases ≥ 8 (P = 0.28), and no heterogeneity was found in the subgroup with the mean age of cases ≥ 8 (I2 = 0%).