"Couples undergoing in vitro fertilization (IVF) have many difficult decisions to make on the road to starting a family. Among them is the decision to use fresh or frozen embryos.
Before freezing methods were refined, fresh embryos were the only option, but as cryopreservation techniques improved, freezing embryos so that not all of the healthiest ones had to be transferred to the woman immediately became more popular. Most IVF clinics today take advantage of embryo freezing.
But whether frozen embryos contributed to the same pregnancy and live birth rates as fresh embryos wasn’t clear. In two papers published in the New England Journal of Medicine, an international group of researchers led by scientists in Vietnam and China report that pregnancy and live birth rates are similar among women who used fresh or frozen embryos."