Prospective evaluation of simple morphological criteria for embryo selection in double embryo transfer cycles

Preventing the occurrence of high-rank multiple pregnancies without reducing the pregnancy rate remains a high priority of in-vitro fertilization and embryo transfer programmes. Our previous study demonstrated that, if there is at least one embryo with a good morphological grade, then the transfer of two (a double embryo transfer) instead of three embryos does not result in a lower pregnancy rate, and that the influence of the number of embryos transferred becomes significant only when poor-quality embryos are transferred. This result allowed us to employ the simple policy of systematically selecting double embryo transfer cycles without affecting the pregnancy rate. Since January 1994, when patients < 37 years of age had more than two embryos available for transfer, only two instead of three embryos were transferred if at least one of the embryos demonstrated a good morphological grade. After a 1 year application of this policy, of the 147 cycles (group A) that fulfilled the above criteria, two embryos were transferred in 92 cycles, while three embryos were transferred in the other 55 cycles. The results of these cycles were compared to those of the control 144 cycles (group B) in which three embryos were transferred, prior to the application of this policy. The on-going pregnancy rates and the incidence of multiple and triplet pregnancies were 24% and 28%, 22% and 23%, and 2% and 9% in groups A and B respectively. The rates were not significantly different. In conclusion, although our prospective trial demonstrated a tendency of decreasing pregnancy rate and an invariable incidence of multiple pregnancies, the very low occurrence of triplets during this period indicated that this policy provided a practical compromise between achieving a high pregnancy rate and an acceptable incidence of triplet pregnancies.