Gonadotrophin Releasing Hormone Agonist Addition for Luteal Support in In-vitro Fertilization and Embryo Transfer Cycles

Inclusion Criteria: 1. Age \< 37 years; 2. One or more high quality embryos have been got in IVF/ICSI treatment; 3. To transfer at lest 2 fresh embryos; 4. Uterine endometrial thickness ≥ 7mm; 5. Patients have signed informed consents. Exclusion Criteria: 1. ≥3 IVF/ICSI/FET cycles and no pregnancy; 2. Polycystic ovary syndrome(PCOS); 3. uterine malformation; 4. endometriosis 5. patients with a history of recurrent pregnancy loss.