Top Assisted Reproductive Technology Literature From 2014

Peter Kovacs, MD, PhD


December 18, 2014

In This Article

Preimplantation Genetic Screening

Obstetrical and Neonatal Outcomes From the BEST Trial: Single Embryo Transfer With Aneuploidy Screening Improves Outcomes After In Vitro Fertilization Without Compromising Delivery Rates
Forman EJ, Hong KH, Franasiak JM, Scott RT
Am J Obstet Gynecol.2014;210:157.e1-6

Forman and colleagues have studied the perinatal outcome based on the findings of their randomized trial in which women were randomly assigned to single blastocyst transfer after aneuploidy screening or double blastocyst transfer. Good-prognosis patients under the age of 43 were enrolled. In the aneuploidy-screening group, blastocysts were biopsied on day 5 and the transfer of a single euploid blastocyst took place on day 6 after quantitative PCR-based comprehensive chromosome testing. In the control group, two blastocysts were transferred. Preterm delivery rate, the incidence of low birth weight or very low birth weight, neonatal intensive care unit admission, gestational age at delivery, and birth weight were compared:

175 patients were randomly assigned; data based on 123 deliveries (following fresh or frozen embryo transfer) were available.

The mean age of the participants (35.1 vs 34.5 years) and the mean number of blastocysts they produced (5.8 vs. 5.3) were similar.

The cumulative delivery rates (fresh + frozen) were comparable in the two groups (69% aneuploidy tested group vs 72% control group).

The delivery of multiples was significantly higher in the control group (47% vs 1.6%).

The chance of having a term singleton delivery (optimal outcome) was 60% in the aneuploidy-screened group vs 31% in the control group.

The risk of preterm delivery was more than twofold increased in the double embryo transfer group (RR, 2.21; 95% CI, 1.04-4.7).

The mean gestational age at delivery was significantly lower in the untested control group (38.3 vs 39 weeks).

The median birth weight was significantly higher (3317 g vs 2778 g) and the risk for low birth weight was significantly lower in the aneuploidy-screened SET group.

There was a trend for fewer very low–birth weight newborns in the genetically tested SET group.

Fewer babies had to be admitted to the NICU, and they spent a significantly shorter time there than those in the chromosomally screened SET group.


This study has shown that comprehensive chromosome screening can help embryo selection and could be used to identify a single embryo for transfer. This method of embryo selection has resulted in improved perinatal outcome when compared with the transfer of two untested embryos, without affecting delivery rates. It has to be pointed out that the results apply to good-prognosis patients who have several blastocysts to choose from at the end of the treatment. It also needs to be pointed out that the approach described in the paper involved in-house genetic testing and transfer in the fresh cycle.

There are only a few IVF labs where in-house genetic testing with such quick turnover is available. In addition, only a small proportion of patients will have five or more blastocysts to choose from on day 5. Furthermore, the price of the test has to be considered, which is also significant. Therefore, this approach cannot be offered in the majority of the IVF centers and to the majority of couples. In their case, other methods may help the selection.


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