Does transferring 2 embryos instead of 1 really reduce IVF pregnancy chances?

During the first week of January some, mostly European, media organizations like the Daily Mail, reported on a study that allegedly claimed that “using two embryos for IVF may cut chances of having a baby by 25%.” Investigators from Nottingham, UK, at least a presented by media outlets, claimed that “if one of two transferred embryos was of poor quality, it dramatically cut the odds of falling pregnant.” The investigators further commented to the media that, the uterus rejects the poor-quality embryo potentially together with the good-quality sibling embryo. The research leader then also suggested that “the current feeling is that a good-quality embryo will be recognized by the body and captured for implantation. But a poor-quality embryo should be rejected by the body.”

Where all of this knowledge supposedly comes from remains, however, unexplained since, as we determined after a careful literature search under the name of the alleged research leader, no such study has, at least so far, been published anywhere. Even more remarkably, however, this research leader further suggested that the research suggested that, putting a poorer quality embryo back with a better quality embryo, is likely to negatively affect the chances of the better quality embryo.

This very much sounds like “fake news” to us because if there is one area of data on a subject in reference with IVF that appears undisputable, then it is the observation that a two-embryo-transfer (2ET) will establish more clinical pregnancies and better live birth rates than an elective single-embryo transfer (eSET).

It is, indeed, remarkable to what degrees some colleagues are willing to sacrifice their scientific integrity to continue pushing for the concept of eSET. So whatever the media are reporting, a 2-ET will always result in significantly better clinical pregnancy and live birth rates than an eSET. In order to pull even in cumulative outcome chances, an eSET always needs a second frozen-thawed embryo cycle.

One more point: Retrospective studies (and this was performed allegedly for IVF cycles between 2009 and 2013) are, in principle, uncontrolled. That means that there usually are reasons why certain patients received eSETs and others 2-ETs. The most obvious explanation, of course, is that better prognosis patients received eSET, while poorer prognosis patients received 2-ETS. What a surprise then when 2-ETs did worse. Yes, not only politics suffer from “fake news!”

This is a part of the February 2017 VOICE.

Norbert Gleicher, MD, leads CHR’s clinical and research efforts as Medical Director and Chief Scientist. A world-renowned reproductive endocrinologist, Dr. Gleicher has published hundreds of peer-reviewed papers and lectured globally while keeping an active clinical career focused on ovarian aging, immunological issues and other difficult cases of infertility.