A new ERA for IVF?

In the UK, just under a quarter of in vitro fertilization (IVF) treatments lead to live births, and this figure can vary dramatically by country, and even by clinic. Implantation failure, when the embryo cannot adhere to the endometrial lining is an influencing factor. Now, clinical trials are underway to validate a new molecular test that could identify the optimum time for embryo transfer and potentially increase IVF success rates: the endometrial receptivity array, or ERA.

Juan Garcia-Velasco, Director of the Madrid fertility clinic IVI, and part of an international team of researchers studying ERA, told The Guardian (1), “We think that about 15 percent of cases of implantation failure are simply due to bad timing.”

For most women, the crucial time during which implantation is likely to succeed can last for only a few days and is governed by a complex range of hormones and genetic factors. The current standard for assessing the status of the womb lining is with ultrasound, but this only provides visual information.

ERA could deliver previously unknown molecular information to fertility specialists. The test involves taking a small endometrial biopsy, then analyzing gene expression to predict the receptivity of the womb lining. In a pilot study of 85 women with a history of failed IVF treatment, researchers analyzed the activity of 238 genes expressed during different stages of the fertility cycle to create a transcriptomic profile, which was then coupled with a computational predictor of receptivity. In this preliminary study, the implantation rate using ERA was 33 percent (2). A larger clinical trial involving 2,500 women in over ten countries, including Spain and the UK, is now underway.

“I think it will make a significant difference to the expectations of couples and how we can explain failures,” said Garcia-Velasco. “Until now, the endometrium was kind of a black box. Now we can say this was the problem and this is what we can do about it.”