Published: September 2017 in Fertility and Sterility
Authors: Cobo A, Coello A, Remohí J, Serrano J, de Los Santos JM, Meseguer M
Institution: Instituto Valenciano de Infertilidad Valencia
This study examined 3,794 embryos created from frozen eggs in 631 cycles, and 9,935 embryos created from fresh eggs in 1,359 cycles, over a period of two years. All the eggs frozen were done so using modern technology (vitrification), which means the results are applicable to eggs frozen today. While embryos created from frozen eggs took, on average, an additional hour to divide and develop, that delay did not have an effect on the quality of the embryos: the percentage of high-grade embryos and low-grade embryos was the same for frozen eggs as it was for fresh. The implantation rate, defined as the number of gestational sacs (early-stage placentas) detected on an ultrasound, was essentially unchanged between the frozen-egg group and the fresh-egg group. And importantly, there was no statistically significant difference between the live birth rates, based on the journey of the egg.