Pregnancy and live birth rates obtained after in vitro fertilization (IVF) are highly variable depending on the practitioner who performs the embryo transfer, regardless of the number of transfers performed per practitioner and years of practice, according to a US study presented in 2016 at the American Society for Reproductive Medicine (ASRM) conference in Salt Lake City.
2016 Study Abstract
Multiple prior studies have demonstrated variation in IVF success rates according the provider performing the embryo transfer procedure. However, these studies were limited by lack of control for embryonic aneuploidy and evaluation of cleavage stage transfers only. Thus, our objective was to isolate the contribution of physician variability on the chance of embryo transfer (ET) success in contemporary ART by evaluating euploid blastocyst transfers in a single practice setting.
Materials and Methods
All euploid blastocyst transfers from 2011 to 2015 were evaluated. The physician performing the ET, maternal age, blastocyst grade, and information regarding fresh versus frozen transfer were recorded. During the study period, 11 physicians were randomly assigned to be “ET physician of the day” in a rotating fashion. To avoid selection bias, all transfers not performed by the assigned “physician of the day” were excluded to assure that the randomness provided by the rotating schedule remained intact. Analysis was performed using chi-squared tests.
There were 2707 euploid ETs performed that met inclusion criteria. The mean number of transfers per physician was 246. There was no difference in maternal age, blastocyst grade, or proportion of fresh vs. frozen transfers among the physicians. The implantation rate (IR), clinical pregnancy rate (CPR), and live birth rate (LBR) differed significantly between worst performing and best performing physicians. When compared to worst performer, an additional live birth could be expected for every 6 ETs performed by the best performer. There was no association between success rates and number of ETs performed by provider during the study period or number of years elapsed since completion of training.
When controlling for embryonic factors by utilizing euploid blastocyst transfers, live birth rate is still strongly influenced by the physician performing the transfer procedure. Given that these data only include ETs in which patients were randomly assigned to a given provider, the impact of the physician factor on success rates is truly isolated. These findings highlight the importance of characterizing optimal ET technique and present an opportunity for improving success rates through remediation of experienced providers and formalized instruction of trainees.