Frozen Embryos Are Just as Good for IVF as Fresh Ones

From TIME - January 11, 2018

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 wasnt 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.

The two studies involved nearly 3,000 women undergoing IVF who were randomly assigned to receive either frozen or fresh embryos. In one study, led by researchers at a single clinic in Vietnam, 36% of the women implanted with frozen embryos became pregnant, while 34% of those implanted with fresh embryos did. Among the women in this study, 34% of those with frozen embryos had a live birth, compared to 31% of those with fresh embryos.

In the other study, led by researchers in China, women at multiple clinics were randomly assigned to receive fresh or frozen embryos. The live birth rate among those with frozen embryos was 49%, compared to 50% among those with fresh embryos.

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The importance of these papers is that it documents what we know, says Dr. Jamie Grifo, program director of the New York University Fertility Center, who was not involved with the studies. The bottom line is that there probably isnt a big difference between fresh and frozen embryos.

The shift to frozen embryos was triggered by a landmark study in the field published in 2012, which found that frozen embryos actually were more likely to successfully implant in the uterus when transferred than fresh embryosand theoretically more likely to result in a full-term pregnancy and live birth.


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