During the IVF process, the emphasis has traditionally been on creating the best possible embryos for transfer. Although this embryo based approach has lead to a steady improvement in pregnancy rates for IVF patients; success rates have reached a plateau during the last decade. It seems appropriate therefore that we now step back and devote similar efforts to bolster implantation by improving the receptivity of a woman’s uterus. Such was the recommendation of a 2006 review article [r1] that suggested in its title that the “…endometrium is a fertility determining factor.” Yet only recently have practical ideas verified how we can optimize the chance for a healthy embryo to implant and grow.
Although most clinics monitor the ultrasound appearance of the endometrium (the lining of a woman’s uterus) this does not always reflect the hormonal, immunologic and nutritional environment where the embryo is expected to implant and grow. In 1998 a study [r2] demonstrated that a small amount of the hormone called “human chorionic gonadotropin (hCG) can be placed into the uterus and trigger a cascade of events that improve implantation. In fact, we now understand that process of “implantation” involves the embryo being “engulfed” as the tissue grows up and around the embryo. hCG promotes that process to take place. This same critical hormone promotes beneficial changes in the uterine muscle and the immune cells in the uterus necessary to enhance pregnancy.
A recent study [r3] measured the effect of putting a small drop containing 500 IU of hCG in the uterus immediately before an embryo transfer. They demonstrated about a 30% improvement in implantation and on-going pregnancy in women that received this treatment. They also tested smaller doses and found no improvement—further supporting that a crucial level of hCG is necessary to induce this measured benefit. As a result of this information, we are encouraging the use of 500 IU of Intra-uterine hCG as part of our embryo transfer routine.