For women undergoing in vitro fertilization, single-embryo transfers are more likely than multiple-embryo transfers to end in a healthy birth, irrespective of whether fresh or frozen oocytes are used, new research shows.
Implantation rates and other traditional assisted reproductive technology outcomes are better with fresh than with frozen donor oocytes, but the one outcome that really matters is a healthy baby, said Alex Polotsky, MD, from the University of Colorado Hospital in Aurora.
"Fresh donor eggs have been available as a fertility treatment for a long time. Using fresh works well, but it is more expensive and requires more coordination," he said at the American Society for Reproductive Medicine 2017 Scientific Congress in San Antonio.
Existing literature suggests that embryo development with fresh eggs is comparable to that with frozen donor eggs, which became available more recently, but data on live birth and obstetrical outcomes are still very limited, Dr Polotsky explained.
"We desperately need more information on outcome measures for fresh and frozen donor eggs," he told Medscape Medical News.
In their study, Dr Polotsky and his colleagues identified all donor oocyte cycles from 2012 to 2014 entered in the Society for Assisted Reproductive Technologies Clinical Outcomes Reporting System (SART-CORS).
The primary outcome was a good obstetrical outcome, defined as a singleton live birth at 37 weeks of gestation with a birth weight of 2500 to 4000 g.
"To control for factors related to egg quality, we looked only at cycles that used eggs from donors," Dr Polotsky explained. "Donor eggs are known to provide the best chance of success for women undergoing IVF."
The analysis involved 28,888 cycles: 5608 (19.4%) performed with frozen oocytes and 23,280 (80.6%) performed with fresh oocytes.
The researchers adjusted for recipient age, body mass index, smoking, race, geographic region, parity, diagnosis, number of available oocytes, intracytoplasmic sperm injection, assisted hatching, day of transfer, and elective single-embryo transfer.
Rates of implantation, clinical pregnancy, live birth, and multiple birth were significantly lower with cryopreserved than with fresh oocytes.
However, after adjustment for covariates, rates of good obstetrical outcomes were similar with frozen and fresh oocytes (22.7% vs 24.5%; odds ratio [OR], 1.00; 95% confidence interval [CI], 90.0 - 1.11; P = .9).
"This is because more double and triple embryos are being transferred with the fresh donor egg approach," said Dr Polotsky.
In fact, electively transferring just one embryo doubled the odds of a good obstetrical outcome (OR, 2.11; 95% CI, 1.96 - 2.27; P < .0001).
"The biggest take-home point is that physicians and patients alike have to refocus on what really matters, which is a healthy baby, above and beyond just a pregnancy. It appears transferring just one embryo, with either approach, is best," said Dr Polotsky.
"When you end up transferring more, you have a much higher chance for prematurity and low birth-weight babies."
Intermediate outcomes, such as clinical pregnancy, are more likely with fresh oocytes, "but you can't take an implantation or clinical pregnancy home," he added. "You need to wait until a baby is born."
"This study emphasizes the need to reinforce what we know," said Kevin Doody, MD, director of CARE Fertility in Bedford, Texas, and immediate past president of SART.
"Patients want the highest chance of pregnancy in the shortest timeframe, and do not fully understand the risks associated with multiple pregnancy. We need to continue to emphasize that more is not better," he told Medscape Medical News.
"The media has often portrayed twins, triplets, and other multiple births in a good light. The reality is that the uterus is often not able to satisfy the nutritional needs and growth needs of more than one baby," he explained.
"Although we all agree that patients should participate in decision-making and we strive to allow great latitude with regard to treatment, the high risk of bad outcomes associated with multiple pregnancy requires that we educate patients and prevent bad outcomes related to bad decision-making," said Dr Doody.
This study was supported by the Clinical Research Reproductive Scientist Training Program (CREST), the National Institute of Child Health and Human Development, the National Institutes of Health, the American Society for Reproductive Medicine, and the Society for Assisted Reproductive Technology. Dr Polotsky and Dr Doody have disclosed no relevant financial relationships.
American Society for Reproductive Medicine (ASRM) 2017 Scientific Congress: Abstract 0-191. Presented November 2017.
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Cite this: Good Obstetrical Outcomes Better With Single-Embryo Transfer - Medscape - Nov 03, 2017.