Women with low ovarian reserve undergoing in vitro fertilization had a higher live birth rate with fresh (40%) compared with frozen embryo transfer (32%), according to a recent study. 

The multicenter, randomized controlled trial included nine fertility centers in China. Researchers investigated whether fresh embryo transfer vs. a freeze-all strategy in women with a low prognosis for in vitro fertilization (IVF) improved live birth rates. Their findings were published in The BMJ.

The trial enrolled 838 women with low ovarian reserve, defined by nine or less oocytes retrieved, antral follicle counts less than five, or serum anti-Müllerian hormone level less than 8.6 pmol/L. Participants were randomized 1:1 to undergo either frozen or fresh embryo transfer. In the frozen transfer group, all embryos were cryopreserved and transferred later, while those in the fresh transfer group underwent embryo transfer within the same cycle as oocyte retrieval. The primary outcome of the trial was live birth, defined as the delivery of a neonate with heartbeat and respiration at 28 weeks’ gestation or more; secondary outcomes included clinical pregnancy, pregnancy loss, multiple gestations, birth weight, maternal complications, and cumulative live birth rate within 1 year of randomization.

In the intention-to-treat analysis, live birth rates were significantly lower in the frozen embryo transfer group than in the fresh embryo transfer group (32% [132 of 419] vs 40% [168 of 419]; relative ratio [RR] = 0.79, 95% confidence interval [CI] = 0.65–0.94; P = .009). Clinical pregnancy rates were also lower in the frozen transfer group compared to the fresh transfer group (39% [164 of 419] vs 47% [197 of 419]; RR = 0.83, 95% CI = 0.71-0.97; P = .02). The cumulative live birth rate within 1 year remained lower in the frozen embryo transfer group (44% [185 of 419] vs 51% [215 of 419]; RR = 0.86, 95% CI = 0.75-0.99; P = .04). No significant differences in neonatal complications, obstetric complications, or birth weight were observed between groups.

Researchers emphasized the need for further research on treatment strategies that prevent fresh transfers— such as back-to-back embryo accumulation cycles or routine preimplantation genetic testing for aneuploidy—to determine their impact on live birth rates in this population.

Full disclosures can be found in the published study.