Liraglutide, a hypoglycemic drug, can reduce weight and improve insulin resistance while stabilizing blood glucose metabolism without increasing the risk of hypoglycemia, and has been approved by the State Food and Drug Administration of China and the US Food and Drug Administration for the treatment of obesity. Polycystic ovary syndrome (PCOS) is the main cause of female anovulatory infertility, and it is also a high-risk group of obesity. Previous studies have suggested that liraglutide improves glucose metabolism, body weight, and inflammation levels in obese women with PCOS, and improves sex hormone profiles and menstrual cycles, possibly contributing to increased fertility.

Therefore, this project intends to test the following hypothesis through a large sample randomized controlled trial in obese and infertile PCOS women who are assisted by in vitro fertilization-frozen embryo transfer (IVF-FET), using liraglutide before transplantation to reduce weight can improve the live birth rate of assisted reproduction.

Inclusion Criteria:

• Women with polycystic ovary syndrome (PCOS) who meet the Rotterdam diagnostic criteria.
• Aged 20-40 years;
• 25 kg/m2 ≤ BMI ≤ 35 kg/m2;
• Have not used any anti-diabetes or weight-loss medications (metformin excluded) within the past 3 months;
• Have at least 1 transplantable frozen embryo available at the research center;
• Able to follow the study's contraceptive requirements.

Exclusion Criteria:

• Diabetic ketoacidosis or other acute complications of diabetes;
• HbA1c ≥ 9.0% before enrollment;
• Using drugs that affect appetite or nutrient absorption within the past 2 months (metformin excluded);
• Uncontrolled hyperthyroidism or hypothyroidism, hypertension, systemic autoimmune diseases, etc. that may affect pregnancy and fetal development;
• 17 hydroxyprogesterone in follicualr phase > 2.0 ng/ml;
• Serious cardiovascular, digestive, liver, or kidney diseases, HBsAg-positive chronic hepatitis B, active pulmonary tuberculosis, or AIDS, etc. that are infectious or hereditary diseases;
• Any psychiatric or psychological disorders requiring drug treatment;
• Poor pregnancy and delivery history: recurrent failed implantations ≥3 times, spontaneous abortions ≥2 times; history of stillbirth, dystocia, or birth defects; previous pregnancies with preeclampsia, eclampsia, or HELLP syndrome;
• Uncontrolled metabolic, autoimmune, or hereditary disease in the husband;
• A contraindication or relative contraindication to using GLP-1 receptor agonists (history of medullary thyroid carcinoma or family history of medullary thyroid carcinoma, acute cholecystitis or pancreatitis in the acute phase or history of previous attacks, GLP-1 receptor agonist allergy, etc.);
• Failure to comply with the contraceptive requirements of the study design;
• Failure to take medication regularly and follow up;
• Current smokers, drug addicts, alcoholics, or individuals with substance abuse;
• Participants who have participated in any clinical trial within the past 3 months prior to screening;
• Individuals with other conditions deemed unsuitable for participation in this clinical trial by the investigator;

De-identified individual participant data will be available if researchers provide a methodologically sound proposal and contact to the principal investigator. Data requestors will need to sign a data access agreement.