In this study in the February 2010 issue of Fertility and Sterility, the authors monitored almost 2000 IVF cycles and found in this group of single-embryo transfers there was no statisically significant difference observed in the probability of monozygotic twinning between the cleavage-stage (Day 3) and the blastocyst group (Day 5).  The odds of an identical twin pregnancy was 2.6% in the cleavage-stage group (8/308) and 1.8% (5/271) in the blastocyst group The odds ratio for the incidence of monozygotic twinning after Day-5 embryo transfer was calculated to be 0.71 compared to the Day 3.

Despite the stage of the embryos at the time of transfer, one must be mindful of the almost 2% chance of monozygotic twins when selecting the number of embryos to transfer.

But in most of the U. S., couples are faced with more than the disappointment of a small increment  in the chance of a failed cycle. In most European countries, IVF is covered by the national health service so an additional cycle is less of a financial burden. In non-mandated states in the U.S, the couple is also faced with the cost of another fresh or frozen embryo cycle.

Our success rates in good prognosis patients who would be candidates to consider an eSET, our success rates are better than reported in the Swedish study and the difference in live birth rate between the two groups should be small.

In order to encourage couples to choose the single embryo option we are studying financial incentives to reduce the impact of a possible failed cycle which may not have occurred if two embryos had been transferred.

We would like to hear what financial incentive would help you choose a single embryo transfer if the difference in success rate was not statistically significant. You can post your responses to this blog.

Increased risks of twins over a single IVF baby include a greater chance of prematurity, cerebral palsy, birth defects, developmental delays and death for the babies, and gestational diabetes, bleeding and preeclampsia for the mother.

Researchers from Sweden expanded the results from a 2004 study showed a difference of 43% live birth from two embryo transfer; 39% from a  single embryo transfer. That difference was not statistically significant. One third of the patients in the double-embryo group had twins or triplets, compared with only 1% in the single-embryo group.

At Reproductive Partners we have been encouraging single embryo blastocyst transfer in appropriate couples who have a good prognosis for success and excellent embryo quality. The biggest barrier to acceptance of this concept seems to be financial. In the U.S., most couples pay for IVF out-of-pocket, where in many European countries the procedure is covered by national health insurance. So a couple with a failed cycle not only has to deal with teh disappointment of not succeeding, they are faced with paying for another fresh or a frozen cycle.