Double Embryo Transfer after IVF vs. TWO-Single Embryo Transfers: time to refine our definition of treatment success

Fertility treatment in the USA has always been different from most of the rest of the world. Although the first IVF pregnancy was conceived in England; the first IVF pregnancy involving ovarian stimulation  to produce more eggs occurred in Norfolk, VA in 1981. Thus began the modern trend of producing multiple embryos in order to boost the chance for a pregnancy. We’ve achieved that goal. As I wrote about several months back fertility treatments have become both safer and more successful. Yet pregnancy following IVF still has higher risks than naturally conceived pregnancies. New data now supports that lowering the number of embryos transferred per cycle may be the key to both higher pregnancy rates and lower risks. Here’s what we now know.

Multiple pregnancies—twins in particular—remain fairly common after IVF. In 2013, (the most recent year that we have outcome data available for ) most embryo transfers involved two embryos or dual embryo transfer (DET). Not surprisingly, the incidence of twins or higher order multiples nearly reached 30% of those that became pregnant. By comparison the natural incidence of twins is about 2%. One of the major factors that appear to drive this continued trend for twins over singletons is that most patients don’t have enough information available to them to make a fully informed decision of one vs. two embryos.  In fact as one recent editorial stated “it is not the fear of multiples that drives decisions about the number of embryos to transfer…but rather the fear of not conceiving at all .”

Many of the most successful programs have been urging their patients to consider single embryo transfer based upon their clinic-specific success rates. Some have even demonstrated that imposing a mandatory policy of single embryo transfer (SET) is well supported by patients in these settings . But now we have new data suggesting that patients at the typical center should also be considering SET.

A just published study  using the national database for IVF centers’ information gathered from 2006 to 2012 has provided new insights into live birth rates (LBR) from elective SET vs. DET. They demonstrated that LBR is as good as or better with two SET cycles than with one DET cycle. In fact, in some patients the LBR was up to 20% higher with an incidence of twins of around 1 to 3% (due to a single embryo splitting and forming identical twins). Other studies have also demonstrated that when two or more embryos are transferred, the excess embryos have a negative effect on the one remaining. This impact may manifest as a low birth weight, a higher risk of preterm labor or an elevated risk of miscarriage. It can even contribute as adverse neurologic effects on the embryo that survives to term; resulting in a child with cognitive or developmental impairment. The studies’ authors concluded that “success for modern IVF should be defined as a singleton pregnancy that results in a healthy singleton infant who is born at term.”

The greatest challenge toward achieving that goal remains the cost and availability of fertility services. Currently, only about a quarter of the states require insurance companies provide any coverage for fertility treatments. However, databases  demonstrate that in states where IVF is covered by insurance; fewer embryos are transferred per cycle and lower multiple gestations occur. This actually lowers the cost to insurance companies since there is universal coverage mandated for pregnancies and singleton pregnancies cost less. Therefore, the burden for the cost of multiple pregnancies tends to fall back upon the insurance companies that often opposed providing the fertility treatment as a covered benefit. Hopefully, as this information becomes more widely available we will see more patients choosing SET as the best outcome; instead of simply making a choice based upon personal financial pressures  which are becoming more a by-product of where they live .

[r1]Link to first IVF  http://www.fertstert.org/article/S0015-0282(07)02985-8/fulltext

[r2]Link to https://www.sartcorsonline.com/rptCSR_PublicMultYear.aspx?ClinicPKID=0

[r3]http://www.ajog.org/article/S0002-9378(15)00248-3/abstract

[r4]http://www.fertstert.org/article/S0015-0282(11)02256-4/fulltext

[r5]http://www.ajog.org/article/S0002-9378(15)00127-1/abstract

[r6] http://www.asrm.org/insurance.aspx

[r7]http://www.fertstert.org/article/S0015-0282(10)00983-0/abstract

[r8]http://familybuilding.resolve.org/fertility-scorecard

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