Image courtesy of Flickr.
For couples facing infertility, in vitro fertilization (IVF) offers hope of achieving parenthood. IVF involves fertilizing eggs with sperm in a laboratory, supporting their development into embryos, and transferring the embryos into the uterus. In many cases, the transfer is performed at the blastocyst stage of embryo development, about five to seven days after fertilization. Since the first IVF baby in 1978, success rates have risen substantially from single digits, but IVF does not always result in pregnancy. Older women have lower success rates, as they tend to have a reduced number of eggs available for retrieval and lower quality eggs that are less likely to develop into “euploid” embryos containing the normal number of chromosomes. After multiple failed embryo transfers, patients may be diagnosed with recurrent implantation failure (RIF), leading to uncertain diagnoses and risky interventions.
To better understand RIF, a team led by Emre Seli, the medical director of Yale Fertility Center, analyzed clinical pregnancy and live birth rates from over one hundred thousand women across twenty-five clinics. Among women who had two additional euploid blastocyst transfers following three failed attempts, the live birth rates for the fourth and fifth euploid blastocyst transfers were high, with a cumulative success rate of 98.1 percent after five transfers. Their findings suggest true unexplained RIF is rare, with an estimated prevalence of less than two percent. “If there is no visible abnormality in the uterus […] it is extremely likely that they will achieve a successful outcome if they continue to try,” Seli said.
The study challenges the notion that multiple implantation failures automatically indicate RIF due to an inherent problem with the patient’s uterus making them unable to conceive, offering reassurance to prospective parents. Seli emphasized setting realistic expectations for patients and advocated a “marathon” approach to parenthood for greater comfort and perspective. For many, continuing embryo transfers is the best plan when no clear cause of implantation failure is found.