In a nutshell
This study compared live birth rates and newborn characteristics after fresh and frozen embryo transfers.
Some background
In-Vitro Fertilization (IVF) involves fertilization of the female egg with the male sperm in a lab dish, and then implanting the fertilized egg into the womb lining three to five days after fertilization. Recent advances in fertility treatment have enabled women to freeze embryos (eggs fertilized with the male sperm prior to freezing) for future use. There are two methods used to freeze down embryos, slow cooling and fast cooling. Recent studies suggest that fast-frozen embryo transfers may have better outcomes compared to fresh (non-frozen) transfers.
Methods & findings
This study aimed to compare outcomes between fast-frozen and fresh embryos in IVF.
The study involved 1,209 infertile women who underwent either fresh or fast-frozen embryo transfers at a private clinic in Sydney, Australia. Female eggs and male sperm were combined in a lab dish to form an embryo as part of the IVF procedure. On day 5 of growth the embryos were either fast-frozen and stored until use, or implanted freshly into the womb.
The fresh and frozen embryo groups were divided into grade 1 and grade 2 embryos, with grade 2 embryos being of slightly lower quality. Overall, live birth rates were comparable after fresh and frozen embryo transfers in both groups. Specifically, the live birth rate for grade 1 embryos was 53% after fresh, compared to 55% after frozen transfers. The live birth rate for grade 2 embryos was 35% after fresh, compared to 30% after frozen transfers. Furthermore, length of pregnancy was on average 0.3 weeks longer in the frozen embryo group and babies were born on average 142 grams heavier compared to fresh transfers.
The bottom line
The authors conclude that patients undergoing fast-frozen embryo transfer have an equal chance of achieving pregnancy and have improved neonatal outcomes compared to fresh embryo transfers.
The fine print
There are only a handful of studies which have examined the beneficial effects of fast-frozen embryo transfers over fresh transfers, therefore, more studies are needed to validate the current results.
What’s next?
If you are considering frozen embryo transfer, please discuss any questions you may have with your doctor.
Published By :
Fertility and Sterility
Date :
Feb 27, 2014
