This study aims to explore whether the application of low-dose HCG in luteal support can improve the pregnancy outcomes of natural cycle frozen embryo transfer in obese patients

In ART, due to ovulation induction and the particularity of the population, luteal phase deficiency usually exists, and in clinical practice, luteal phase support is routinely strengthened. Progesterone is commonly used for luteal support in clinical practice. According to the Chinese expert consensus on luteal support, HCG can be used for luteal support in the absence of OHSS. HCG can increase progesterone secretion by endogenous stimulation of luteal function and exogenous addition of HCG to enhance luteal support, thereby increasing progesterone production and maintaining luteal function.

At present, it remains unclear whether HCG can improve pregnancy outcomes. Previous studies have indicated that compared with conventional luteal support, HCG has not significantly improved the pregnancy outcomes of frozen-thawed embryo transfer in ovulation cycles (NC). However, with the development and progress of FET technology, while reducing the impact of the technology on frozen embryos, we once again explored whether adding HCG on the basis of traditional luteal support in NC-FET could improve the pregnancy outcomes of obese or overweight patients, providing a theoretical basis for the clinical application of HCG.

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

female