Freezing and subsequent transfer of embryos gives infertile couples just as much of a chance of having a child as using fresh embryos for in vitro fertilization (IVF), researchers found.

In results published in The New England Journal of Medicine, the research team shows that ongoing pregnancy rates and live births were equivalent in a group of IVF women implanted with frozen embryos compared with fresh embryos.

"Frozen embryo techniques are growing in popularity in fertility clinics worldwide. This is one of the reasons why our research is important for fertility clinicians and researchers, and of course couples who are hoping to have a child," says the lead author.

The study investigated almost 800 women who had infertility not related to polycystic ovarian syndrome (PCOS). Women were given one cycle of IVF, where either a transfer of fresh embryos occurred, or all embryos were frozen and one cycle of thawed embryos occurred subsequently without the use of IVF drugs.

After the first completed cycle of IVF, ongoing pregnancy occurred in 36% of women in the frozen embryo group, and in 35% of the fresh embryo group.

Rates of live birth after the first embryo transfer were 34% in the frozen embryo group, and 32% in the fresh embryo group.

"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 the author.

"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.

"Our key finding is that freezing embryos for IVF is not harming a couple's chances of having a baby. 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."

The senior author says that while many clinics are moving completely away from fresh embryo transfers, the freezing process adds additional costs in IVF and does not result in higher rates of live births. "Couples concerned about such unnecessary costs of freezing all embryos do not need to go down that path, and will still have the same live birth success rate," the senior author says.

https://www.adelaide.edu.au/news/news97342.html

http://www.nejm.org/doi/10.1056/NEJMoa1703768