Background: The implantation process after embryo transfer depends on the embryo quality and endometrial receptivity. It is estimated that fifty to seventy-five per cent of pregnancies are lost due to a failure of implantation. There is evidence that there is an early secretion of human chorionic gonadotrophin before embryo implantation, and this secretion has been linked to an important function in angiogenesis and the inflammatory response that promotes the implantation process. Our objective was to determine the effects of intrauterine injection of human chorionic gonadotropin (hCG) before the embryo transfer in an in vitro fertilisation cycle.
Methods: A prospective randomised study was conducted in Reproductive Medicine Centre PROCREA in Mexico City. Infertile patients who had a medical indication for in vitro fertilisation were studied. Two groups were included (n 210); the intervention group received an intrauterine injection of 500 IU of hCG before the embryo transfer (n 101). The control group (n 109) did not receive hCG. Comparisons were performed using a chi-square test.
Results: The clinical pregnancy rate (CPR) was our principal outcome. The implantation rate was a secondary outcome. The implantation rate was significantly higher in the hCG group compared to the control group (52.4% vs 35.7%, p 0.014). The clinical pregnancy rate was also significantly higher (50.4 vs 33.0%, p 0.010). No adverse effects were observed.
Conclusions: The intrauterine injection of hCG before embryo transfer showed a significant increase in the clinical pregnancy rate. More clinical trials are needed to reproduce these results on this promising intervention. The live birth rate must be included in subsequent studies.