This study aims to assess the association of Anti-Müllerian hormone (AMH) with polycystic ovarian syndrome, premature ovarian insufficiency and fertility. The main objectives include the following: 1. To study the level of serum AMH in women with PCOS and to evaluate the utility of serum AMH in the diagnosis of PCOS. 2. To evaluate the level of serum AMH in women with POI and to evaluate the utility of serum AMH in the management of POI. 3. To evaluate the associations of basal AMH level with FSH level and AFC respectively for women undergoing ART treatment. 4. To determine the optimal regimen of gonadotropin for ovarian stimulation for women undergoing ART treatment. 5. To evaluate the predictive value of serum AMH in reproductive outcomes including oocyte quality, embryo quality, pregnancy loss, clinical pregnancy and live birth rate in women undergoing ART treatment.