Research presented today at the American Society for Reproductive Medicine (ASRM) by scientists from the University of Colorado and Duke University concludes that fresh donor eggs during in vitro fertilisation (IVF) provide a higher chance of implantation when compared with donor eggs that have been cryopreserved. In addition, the study lends credence to the practice of transferring just one embryo during IVF to avoid complications that accompany multiple births, bucking the historically prevalent method of transferring two or more embryos to increase the odds of pregnancy.
“The most impressive finding that has relevance for all patients undergoing IVF is that performing the transfer with one embryo greatly increases the chance of a healthy baby, the desired objective in IVF,” said the senior study author. “We encourage patients and physicians alike to set their focus on the horizon of achieving a healthy birth outcome. Just achieving a pregnancy is not sufficient.”
Researchers conducted this extensive study because existing medical literature does not clearly indicate whether fresh or frozen donor eggs lead to better birth outcomes for patients undergoing IVF. Their study examined a three-year swath of the latest available United States data reported to the Society for Assisted Reproductive Technology (SART). This study looked at only those cycles that used eggs from donors in order to control for factors relating to egg quality. Donor eggs are known to provide the best chance of success for women undergoing IVF.
Among the examined cycles, healthy birth rates were similar with fresh and frozen eggs, with one important caveat. Double and triple embryo transfers were found to be significantly more prevalent among cycles using fresh donor eggs, leading to a higher incidence of multiple pregnancies (twins or more). Multiple births are known to have increased risks of complications for both mother and child, including premature birth and low birth weight. When controlling for the factors known to affect IVF success, choosing to transfer just one embryo doubled the chance of a healthy baby, the desired objective in IVF.
Frozen donor eggs provide a more economical and convenient way to obtain fertility treatment with donor eggs, while fresh eggs (non-frozen) tend to be more expensive and require the patient to coordinate with a single egg donor. Irrespective of the type of donor egg a patient pursues, opting for a single embryo transfer was shown to lead to a higher chance of a healthy pregnancy and birth.