Due to the injection of gonadotropin releasing hormone agonist (GnRH-a) before controlled ovarian hyperstimulation (COH), the scheme of prolonged early follicular period protocol has obvious advantages in achieving ideal egg number, increasing endometrial receptivity to embryo transfer, inhibiting endogenous luteinizing hormone (LH) peak and reducing cycle cancellation rate. The full dose of long acting GnRH-a was also applied before COH in the mid luteal Hypergrowth program, and the mechanism of its lowering tone was similar. But whether the clinical and perinatal outcome of early follicular hyperlengthening is as effective as that of mid luteal hyperlengthening has not been reported at home and abroad. Moreover, there is a lack of prospective randomized controlled studies.

One injection of 3.75mg GnRHa was injected on the 1st-3rd or 21st-23rd day of menstruation. The level of estradiol (E2), progesterone (P), luteinizing hormone (LH) in peripheral blood and the number of follicles in bilateral ovarian internal sinuses were monitored on the 32nd-38th day after pituitary hyporegulation.Gonadotropin (Gn) will be given after pituitary desensitization. When the diameter of at least two follicles ≥ 18mm or more than three follicles ≥ 17mm, the trigger of human chorionic gonadotropin (hCG) will be given and oocyte will be retrieved. The selective fresh single blastocyst transplantation will be carried out on the 4th-6th day after oocyte retrieval. HCG test at 12nd day after transplatation. Follow-up investigation will given during the pregnancy and perinatal period.

Inclusion Criteria:

1. Tubal factor infertility;
2. polycystic ovary (PCO) or polycystic ovary syndrome (PCOS) patients;
3. Patients of mild to moderate endometriosis；
4. Oligoasthenospermia in male；
5. More than 5 antral follicle count (AFC) on both ovaries；
6. Unexplained infertility: there is a history of no contraception and pregnancy for more than 1 year, no clear cause of infertility such as ovulation, fallopian tube, endometrium and male factors is found, or the above factors return to normal after treatment.

Exclusion Criteria:

1. History of adverse pregnancy and childbirth；
2. Unilateral ovariectomy；
3. Uterine malformation, intrauterine adhesion, submucous myoma；
4. Chromosomal abnormality of both husband and wife；
5. Patients with contraindications of assisted reproductive technology or pregnancy: such as uncontrolled diabetes mellitus, undiagnosed liver and kidney dysfunction, history of deep vein thrombosis, history of pulmonary embolism, history of cerebrovascular accident, uncontrolled hypertension, heart disease, suspected cervical cancer, endometrial cancer, breast cancer or previous history, undetermined vaginal bleeding;
6. Unable to be regularly follow up；
7. Participating in other clinical trials；
8. No fresh single blastocyst transfer.

Statistician blindness