Frozen embryos result in just as many live births as fresh embryos, according to a study of around 800 women with fertility problems.
During a typical IVF cycle, “fresh” embryos are usually planted into a woman’s womb once an egg has been successfully fertilised with her partner’s sperm. Some women choose to have one or more embryos frozen and then stored, for a number of reasons, for implantation at a later date.
The 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 per cent of women in the frozen embryo group, and in 35 per cent of the fresh embryo group. Rates of live birth after the first embryo transfer were 34 per cent in the frozen embryo group, and 32 per cent in the fresh embryo group, the researchers from Vietnam and Australia found. Their work is published in The New England Journal of Medicine.
Dr Lan Vuong, the lead author from the University of Medicine and Pharmacy at Ho Chi Minh City, said: “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.”
The women who participated in the study had infertility not related to polycystic ovarian syndrome (PCOS), a set of symptoms due to elevated male hormones in women.
“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,” said co-author Professor Ben Mol, from the University of Adelaide.
“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.”
Professor Mol said 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,” he said.