January 14, 2018
“It’s good that [clinicians] will be able to advise patients that frozen-embryo transfer is as good as fresh, because historically frozen has not been as good”.
“There’s a perception that fresh is better so you start with the fresh ones, and then if the fresh ones don’t take, you’ve got embryos that are frozen that you can use”, she said.
“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.
In a Vietnamese study, rates of live births after the first transfer were comparable between groups: 33.8% with frozen embryos and 31.5% with fresh embryos, according to Lan N. Vuong, MD, PhD, of the University of Medicine and Pharmacy at Ho Chi Minh City, and colleagues.
Frozen embryos result in just as many live births as fresh embryos for in vitro fertilization.
The study included nearly 800 couples undertaking IVF in Vietnam, who received either fresh or frozen embryo transfers on a randomised basis and was completed in under a year. 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.
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 embryos – and theoretically more likely to result in a full-term pregnancy and live birth. The improvement came primarily from a lower rate of pregnancy loss. Ben W. Mol, a professor of obstetrics at the University of Adelaide in Australia.
The second benefit (which is still being debated in the scientific community) is that having a more “normal” estrogen level at the time of embryo transfer may result in a healthier pregnancy.
“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”. But the fact that thawed embryos “produce the same pregnancy rate with less complications should transform the way in-vitro fertilization is practiced”, Vuong said. All women had regular menses and were undergoing their first cycle of IVF or intracytoplasmic sperm injection because of tubal factors, male factors, or both.
“It’s not a lot, but it’s a couple of hundred of dollars that you’re talking about, so obviously that could be part of the choice [for patients]”, he said. Vitrification does not harm the embryos and they can be stored indefinitely.
The rates of the syndrome in the Chinese study were 0.6 percent with frozen embryos and 2.0 percent with fresh.
“Health systems in other countries make it more possible to do proper randomised control trials, so it’s excellent that we are getting those relationships built up”, Chapman said.