Ovarian reserve is the potential of follicles in the ovary to develop into fertilizable oocytes and depends on the number and quality of oocytes. Age is the most commonly used indicator for assessing ovarian reserve. In older women, the number of oocytes decreases and the quality of oocytes declines, resulting in a lower rate of spontaneous pregnancies and a higher risk of spontaneous abortions, fetal malformations and various birth defects. However, for some special populations, age does not represent the true state of ovarian function, such as polycystic ovary syndrome (PCOS) and premature ovarian failure (POF/POI). Patients with PCOS have a higher number of underlying sinus follicles (AFC) and a better ovarian reserve, while patients with POF/POI have a significantly shorter reproductive life due to the congenital lack of oocyte reserve or early depletion of oocytes. In recent years, with the help of anti-mullerian hormone (AMH) measurement, it has become popular to assess ovarian reserve more accurately, especially in the population of adolescent and young women, and to provide them with timely fertility guidance. Characteristics and physiological functions of AMH AMH is secreted by follicular granulosa cells, and its level is relatively stable throughout the menstrual cycle. Blood samples can be collected at any time for the test, reflecting the trend of changes in ovarian reserve in a timely manner, and is of higher value than FSH in predicting ovarian function. The physiological function of AMH itself is also worth mentioning, it can inhibit the conversion of androgen to estrogen in the body, so that estrogen maintains a low level; at the same time, it can reduce the sensitivity of growing follicles to follicle-stimulating hormone (FSH), and inhibit follicle recruitment; as the follicle grows, the level of AMH decreases, and the inhibitory effect on FSH is weakened, so that the dominant follicle can develop and ovulate. AMH changes with age Age is the most important factor affecting AMH secretion. A team from Reproductive Hospital of Shandong University found that AMH peaks at 18 years old, at about 4.56mg/L, and that individual differences in AMH are very large during the reproductive years, according to the AMH measurements of 6,763 Chinese Han women aged 0-64 years old. According to AMH levels, women can be divided into four stages from birth to aging: Childhood (0-10 years old): the primordial follicular reserve increases significantly, with a mean AMH value of 3.09±2.91 mg/L, and rises with age; Adolescence (11-18 years old): the ovarian reserve reaches its peak, with a mean AMH value of 5.02±3.35 mg/L; and childbearing age (18 years old and beyond): Ovarian reserve initiated a decline, with a mean AMH value of 2.95±2.50 mg/L, and decreased with age; depletion phase (after 50 years): mean AMH value of 0.22±0.36 mg/L, no longer correlated with age. AMH was positively correlated with androgen levels (0-50 years), but not with metabolic indicators.Kelton et al. studied AMH levels in 238 women aged 18-46 years, and concluded that 1.15 mg/L could be used as the AMH threshold for diagnosing reduced ovarian reserve. In addition to age, AMH is influenced by other factors at the same time. AMH levels are lower in pregnancy than in non-pregnancy. A previous study that included 2,320 women of childbearing age found that women taking oral contraceptives (OC) had reduced AMH levels, but AMH levels recovered after discontinuing OC, so it is important to pay attention to the patient’s medication status in clinical work; smoking reduces AMH levels, but the dose of smoking is not related to the degree of AMH decline; there are large differences in AMH levels among women of different races, which may be The effect of body mass index (BMI) on AMH is controversial. The correlation between BMI and AMH levels in women with normal ovarian reserve is not obvious, but in women with low ovarian reserve, PCOS, and women of late reproductive age, BMI is negatively correlated with AMH levels. AMH predicts age at menopause Currently, women’s reproductive age is gradually delayed, but the rate of ovarian aging varies widely among individuals, so it is necessary to predict the age of fertility decline and menopause. In women in the menopausal transition, AMH changes before other endocrine indicators. Previous follow-up of 257 women for 11 consecutive years found that the age of menopause could be predicted using AMH and age, and relevant formulas were deduced, but these conclusions were derived from the data of women in late reproductive age or even perimenopausal or infertile women, and it is uncertain whether they are applicable to the prediction of the age of menopause in young women, and there is a lack of data related to the prediction of the age of menopause by AMH in Chinese women. AMH assessment of fertility in oncology patients Radiotherapy for oncology can cause ovarian hypoplasia, leading to infertility and premature menopause. Patients with high pre-treatment AMH levels recover ovarian function faster after radiotherapy than those with low AMH levels. Overseas scholars conducted a 5-year follow-up of 134 breast cancer patients (18-43 years old), and found that 69% of the patients had undetectable AMH during chemotherapy, and a slight increase in AMH levels after chemotherapy. Recruitment of follicles from the primordial follicular pool may be responsible for the rise in AMH after chemotherapy, but this does not mean that ovarian function can be fully restored, and early menopause and premature ovarian failure can still occur. Assessing ovarian reserve status with the help of AMH allows for early fertility preservation. AMH is considered to be a rising star in the assessment of female reproductive health and fertility. With the reduction of the cost of AMH test and the optimization of the test method, the application of AMH test and treatment will be more extensive, and it will become another breakthrough in the field of reproductive medicine.