To explore the optimal effective daily dose of BG2109 to suppress premature luteinizing hormone (LH) surge during COH in female subjects undergoing ART procedures.

This study is a randomized, double-blind, open for active comparator, parallel, multi-center phase II dose-finding clinical study to explore the efficacy, safety and tolerability of different doses of BG2109 compared with Cetrorelix during Controlled Ovarian Hyperstimulation (COH) in Chinese female subjects undergoing Assisted Reproductive Technology (ART) procedures.

Inclusion Criteria:

• Married infertile women aged 20 to 39 years (both inclusive), who are diagnosed with tubal infertility, unexplained infertility, grade I-II endometriosis, or spouses diagnosed with male factor infertility, who meet the criteria for IVF and/or ICSI) using fresh or frozen semen from the male spouse or sperm donor
• BMI 18-25 kg/m2 (both inclusive), body weight range 45-80kg (both inclusive)
• Subjects must have regular menstrual cycles, specifically defined as ≥25 days, ≤35 days.
• The serum sex hormone levels during the screening period must be performed in the early follicular phase, and the basal serum follicle-stimulating hormone (FSH) <10 IU/L, LH, estradiol(E2), prolactin(PRL),testosterone(T) levels are within the laboratory normal range, or the investigator considers them as abnormal but not clinically significant
• The subject is clinically assessed and agree to undergo fresh cycle embryo transfer in the first IVF-ET/ ICSI-Embryo Transfer(ET) cycle, with a maximum of two embryos transferred.
• Within 1 year before randomization, the presence of bilateral ovaries is clearly visible on transvaginal ultrasonography with no significant abnormalities, and appendages are normal. Both ovaries must be available for oocyte retrieval
• Subjects must sign the Informed Consent Form (ICF) and be willing and able to abide by the protocol-specified study procedures

Exclusion Criteria:

• Those who have undergone 2 or more COH of IVF/ICSI-ET before screening, but have not achieved clinical pregnancy.
• Those with previous IVF or ART failure due to sperm/fertilization problems whose related medical condition has not been improved.
• Either subjects or their spouses or both of them are known to carry abnormal chromosomal structures, or patients known to have single-gene genetic diseases or serious diseases with genetic susceptibility requiring Preimplantation Genetic Diagnosis(PGD) before embryo transfer.
• Those with high risk of ovarian hyperstimulation syndrome(OHSS)
• Those with low ovarian function at screening, with at least one of the following: poor ovarian response in the past; less than 6 antral follicles (AFC) with a diameter of < 10 mm seen on bilateral ovary transvaginal ultrasonography at Day2-3 of menstrual cycle; anti-mullerian hormone(AMH) < 1.1 ng/ml.
• Subjects who used gonadotropins for ovarian stimulation or drugs that affect ovarian function within 30 days prior to screening.
• Subjects with abnormal thinprep cytology test(TCT) results that are judged by the investigator as clinically significant and require treatment within 6 months before screening.
• As judged by the investigator, subjects with clinically significant gynecological diseases at screening
• Those previously or prior randomization suffering from the cancer of uterine, ovarian, breast or hypothalamus or pituitary gland.
• Those with a positive serum β-hCG test result at the screening visit or the visit on Day 1 of ovarian stimulation.
• During COH, LH ≥10 U/L, and the LH level was 2.5 times higher than the baseline value before D0 (inclusive).

Masked for BG2109 dose groups and open for the active controlled group.