HCG refers to human chorionic gonadotropin, and HCG is given after IVF to maintain the luteal function, assist the embryo to land, and play a role in preserving the fetus. 1. Maintaining luteal function: Usually, IVF will go through the process of down regulation, ovulation stimulation and egg retrieval, etc. After down regulation, the ovary’s own function may be inhibited, but the support of the ovarian corpus luteum is needed after embryo transfer. If the pregnant woman’s own ovarian function is insufficient, she will need to take HCG to maintain the ovarian corpus luteum function in order to promote embryo implantation. 2. Assisting embryo implantation: HCG can assist the uterine wall to become softer, reduce the rejection reaction of the endometrium, assist the embryo implantation, and create an environment suitable for the growth and development of the embryo. 3. Foetus preservation: HCG can promote the secretion of estrogen and progesterone after transplantation, which can prevent preeclampsia and protect the growth and development of the fetus. HCG should be used under the guidance of a doctor, avoid unauthorized use of drugs to avoid adverse effects. If during the use of medication, pregnant women experience abdominal pain and other symptoms, it is recommended to consult a doctor in a timely manner, improve the relevant examination, clarify the cause of the disease, and take appropriate measures to deal with it.