During the early years of IVF treatment, it was always assumed that transferring more embryos would improve success rates. Even 20 years ago, it quickly became apparent that this success came at the expense of a high multiple birth rate. In response o this, many European countries and Australia limited the number of embryos that could be legally transferred to woman’s uterus. While laudable, these restrictions tend to be rigid and do not always take into account the age of the producer.
In the U.S., we have adopted a voluntary system through the American Society of Reproductive Medicine (ASRM). The ASRM has published guidelines that take into account maternal age and are more flexible. However, as seen in the recent case of the famous octuplets, there are no serious consequences when a poor outcome is attributed to not adhering to these guidelines.
While these measures have greatly reduced the incidence of triplets and higher-order multiple births, the incidence of twins remains high, especially with egg donation. Many patients may think this is fine. In fact, many couples express a desire to have twins. Their preferences are affected by a belief that transferring two or three embryos improves success rates, and, for some, a financial motive that sees twins as a “two-for-the-price of one.”
The success rate belief may be inaccurate. Many European studies, as well as our experience, strongly suggest that the success rates with two day-3 embryos is equal to the success rate with one good quality (day-5) blastocyst. The ASRM guidelines allow either choice. Yet, many clinics are still transferring two blastocysts, with predictably high twin rates. So, what’s wrong with that?
The problem with twins is that they have a 50% chance of being born prematurely. As a result, they have higher rates of cerebral palsy and other complications of prematurity. The combined medical costs from IVF twins due to ICU care and life-long complications from prematurity are easily in the billions of dollars. Furthermore, from conception to delivery, there is a reduced chance of actually delivering two live babies. Even when twins are born close to term and are healthy, there are considerable financial and emotional costs associated with them.
With appropriate statistical analysis, it may be possible to demonstrate that the chance of a live birth is the same after the transfer of one blastocyst compared to the transfer of two embryos.
While twins may seem cute and a bargain at first, patients undergoing egg donation should inform themselves of the risks of twins and discuss the potential merits of single embryo transfer (SET) with their physician.
- Michael Feinman, MD
Medical Director, HRC Fertility
Huntington Reproductive Center Medical Group