Human chorionic gonadotrophin (hCG): can it facilitate implantation after embryo transfer?

This study investigated if human chorionic gonadotrophin (hCG) improves implantation in women seeking fertility treatment. They found that hCG treatment improved implantation rates after embryo transfer (ET; the process of transferring fertilized eggs into the womb of a woman undergoing in vitro fertilization).

Patients with infertility seek treatment using assisted reproductive techniques (ARTs). There are a number of steps involved in fertility treatment. This includes harvesting eggs, in vitro fertilization (IVF) and intra-cytoplasmic sperm injection (ICSI). When an embryo is fertilized, it can be transferred into the woman's uterus. This is called embryo transfer (ET). In order to become pregnant, the embryo must implant (attach) in the uterus wall. Unsuccessful implantation accounts for 50-75% of fertility treatment failure.

One important chemical for implantation is human chorionic gonadotrophin (hCG). hCG is a hormone. Some studies suggest administering hCG into the uterus before ET improves implantation rates. However, other studies suggest that large volumes of hCG can have a negative effect. It is unclear if a certain volume or concentration of hCG may facilitate implantation after ET.

This study included 200 women undergoing ET following IVF/ICSI. Patients were randomly assigned to receive hCG or an equal volume of placebo (inactive solution). The dose of hCG used was 500 IU. This was administered into the uterus before ET. Implantation, clinical pregnancy, and live birth rates were assessed in all patients.

The implantation rate was significantly higher in women that received hCG – 28.8% vs 18.2% with placebo. There was a 58% greater chance of implantation in hCG-treated patients. The clinical pregnancy rate was similar in both groups (42% hCG vs. 30% placebo). Clinical pregnancy rates were higher in hCG-treated patients under 40 years of age (45.6% vs. 27.8%). The number of live births was similar in both groups. 

The authors concluded that hCG treatment improved implantation rates after ET.

In this study, some embryos were frozen and others were fresh when transferred. Fresh embryos receive hCG to induce maturation. This might impact the findings in this study and more research is needed. 

If you have any concerns regarding fertility treatment, please consult with your physician.