Fresh or frozen embryos equally viable in IVF

Frozen embryos are just as viable as fresh ones in IVF treatment, joint Vietnamese-Australian research has shown.

In a paper published in the New England Journal of Medicine, researchers from Ho Chi Minh’s University of Medicine and Pharmacy and My Duc Hospital, together with others from South Australian institutions including the University of Adelaide’s Robinson Research Institute (RRI), reveal that pregnancy and live birth rates are almost identical for fresh and frozen embryos used in IVF cycles.

“Our key finding is that freezing embryos for IVF is not harming a couple’s chances of having a baby,” says the RRI’s Ben Mol. “After the first fresh embryo transfer, it will be possible to freeze the remaining embryos and transfer them one by one, which is safe and effective.”

To make their finding, the researchers looked at almost 800 women who suffer from infertility. The women all went through one cycle of IVF treatment, each receiving either a fresh or thawed embryo.

After the cycle, pregnancy rates were almost identical for the two cohorts – 35% for those who received a fresh embryo, and 36% for those who received a frozen one. Subsequent live birth rates were also very similar – 34% for the thawed embryos and 32% for the fresh.

The finding comes on the back of trial results from a 2014 Chinese study that found frozen embryo transfer increased pregnancy rates in women who have a condition called polycystic ovary syndrome (PCOS).

“Previous research has shown that women who experience infertility because of PCOS benefit from significantly higher live birth rates from frozen embryos in IVF procedures, but evidence was lacking for this approach in non-PCOS patients,” says Mol. 

“This new study shows that infertile women not suffering from PCOS have equivalent live IVF birth rates from frozen embryos, which is important news for infertile women worldwide.”

He adds that many IVF clinics around the world are currently moving away from fresh embryo transfer and opting to use frozen ones instead. He says the study results should reassure patients that both methods carry very similar success rates.

Co-researcher Lan N. Vuong from My Duc Hospital, however, sounds a note caution over the findings.

“Our research results are specific to a common freezing method known as cryotech vitrification,” he says, “so it may not apply to all embryo freezing techniques currently being used. Further research will be needed to compare pregnancy outcomes and live birth rates from other embryo freezing techniques.”