The Application of HCG in Luteal Support for Frozen Embryo Transfer in Ovulation Cycle of Obese Women

Inclusion Criteria: * Age ≤37 years old ② Prepare the endometrium in the natural cycle/ovulation induction cycle ③ BMI≥24 according to the overweight standard for the Asian population ④ Single blastocyst transfer (including IVF and ICSI-assisted pregnancy) ⑤ At least one frozen blastocyst remaining in the IVF/ICSI cycle with a Gardner morphology score of ≥4BC, and the age of the frozen embryo is D5 or D6 Exclusion Criteria: * There is a history of adenomyosis, hydrosalpinx, intrauterine adhesions or untreated submucosal fibroids of the uterus * Uterine malformations; ③ The endometrial thickness on the conversion day is less than 7mm, or the cycle was cancelled during the endometrial preparation process before frozen embryo transfer due to the endometrium being less than 7mm in the past. * Have a history of the immune system, such as antiphospholipid syndrome/systemic lupus erythematosus/rheumatism; ⑤ Diabetic patients who have not been controlled by standardized medication; ⑥ Those who have undergone embryo transfer more than or equal to two times without achieving a live birth ⑦ Those whose embryos to be thawed and thawed are from donated or frozen egg sources, or have undergone two freezing operations