Published: Fri, January 12, 2018
Medicine | By Douglas Stevenson

Frozen embryos just as effective as fresh alternative in IVF treatment

Frozen embryos just as effective as fresh alternative in IVF treatment

"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".

The study investigated nearly 800 women who had infertility not related to polycystic ovarian syndrome (PCOS), a common health problem caused by an imbalance of reproductive hormones that can lead to infertility.

"Among infertile women without the polycystic ovary syndrome who were undergoing IVF, the transfer of frozen embryos did not result in significantly higher rates of ongoing pregnancy or live birth than the transfer of fresh embryos", one of the studies concluded.

While there was no significant difference between groups in rates of biochemical pregnancy, clinical pregnancy, implantation, ongoing pregnancy, and overall pregnancy loss, a post-hoc analysis showed that the rate of second-trimester pregnancy loss was lower in the frozen-embryo group than in the fresh-embryo group (1.5% versus 4.7%; RR 0.33, 95% CI 0.16-0.68, P=0.002).

Frozen embryo techniques are growing in popularity in fertility clinics worldwide.

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

For the study, women were given one cycle of IVF where either frozen or fresh embryos were implanted.

But the study suggests it may not increase the chances of a live birth compared to fresh embryos in the study population.

The study by Chen et al was supported by grants from the National Key Research and Development Program of China, the Major Program of the National Natural Science Foundation of China, and the State Key Program of the National Natural Science Foundation of China.

"This is an emerging issue of immediate and important concern for couples who are seeking in-vitro fertilization treatment", said Zhang, the Susan Dwight Bliss Professor of Biostatistics at YSPH. In those cases, fertility experts believe that freezing the embryos to give the woman time between when the eggs are extracted and fertilized, after she has received hormones to produce more eggs than her normal cycle would, may provide a more receptive uterine environment for an embryo to grow.

It was her frozen embryos that gifted her two daughters, Melissa, now 20 years old, and Ashley, 17.

Together, these factors prompted many clinics to advocate freezing of all embryos. But some experts point out that the findings could also justify use of fresh embryos as well. But it's not clear whether frozen-embryo transfer would hold the same benefit in ovulatory women with infertility, who don't have PCOS.

Vuong added that the results of the current study are specific to a common freezing method called Cryotech vitrification, so they may not apply to all current embryo freezing techniques: "Further research will be needed to compare pregnancy outcomes and live birth rates from other embryo freezing techniques".

"Based on these papers, there is no harm in freezing embryos", says Grifo. "We have done a cost-effectiveness analysis of the two treatments and found that freezing embryos and subsequent transfer is not cost-effective over fresh transfer".

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