Several studies have shown that a small amount of the hormone human Chorionic Gonadotrophin (hCG) infused into the uterus shortly before embryo transfer may increase the chance of an embryo implanting. This is an ‘Add-on’ treatment that Fertility Associates currently offers.

The chance of an embryo implanting depends on the quality of the embryo and the receptivity of the uterus. Little is known about how to influence the receptivity of the uterus but there have been several studies looking at the infusion of a small amount of the hormone hCG before embryo transfer.

A recent meta-analysis looked at the results from 15 randomised control studies that included over 2500 patients. The conclusion was that on average infusion of hCG increased the chance of a live birth after embryo transfer. It also appeared to lower the chance of miscarriage. hCG infusion seemed to be more effective for the transfer of fresh embryos than frozen embryos. An infusion within 15 minutes of embryo transfer seemed to be more effective than an infusion done earlier, and a dose of around 500iu seemed to be better than higher doses. We have chosen a dose of 500iu hCG timed 5-10 minutes before embryo transfer as our preferred approach.

  • hCG is made by the embryo from about 5-7 days after fertilisation. The embryo and then fetus makes increasing quanities of hCG throughout pregnancy. hCG is the hormone that is measured in pregnancy tests, when there is enough hCG to be detected in the blood or urine.
  • hCG’s main role is to stimulate the ovaries to make the hormone progesterone, which supports the lining of the uterus to maintain a pregnancy.
  • Experiments show that hCG also influences the level of hormones and growth factors within the uterus and even within the embryo itself around the time of implantation.
  • hCG may also influence cells involved in the immune response of the uterus to the embryo, allowing the uterus to accept the embryo.

Overall, the evidence for a potentially beneficial effect of hCG infusion is quite high, so this is one of the Add-ons which we classify as of ‘possible benefit’. We will need more evidence before we would make hCG infusion a routine part of IVF treatment.

For instance, we do not know whether other things we do, such as using ‘Embryo Glue’ during embryo transfer, have the same effect, so it could be that hCG infusion has less effect in our IVF programme than in those that took part in the randomised controlled studies.