Is double frozen blastocyst transfer better than sequential single frozen blastocyst transfers in womenover >35 years of age? Freeze-all blastocyst transfer cycles women aged >35

Aim: This study aimed to assess live birth rates after double blastocyst transfer versus sequential single blastocyst transfers after freeze-all cycles in women aged over 35 years. Material and Methods: Between January 2016 and December 2018, we conducted a retrospective analysis of 296 women over 35 years of age who had all their embryos frozen and subsequently transferred. The inclusion criteria were women over 35 years of age who had their entire cohort of embryos frozen at the blastocyst stage for different indications based on physician preference. All patients had at least two good-quality embryos in their frozen cohort. Preimplantation genetic testing cycles were excluded from the study. Demographic data were extracted from patient files and electronic databases. Women were categorized based on their mode of embryo transfer (D-FBT vs. SS-FBT). The couple decided to adopt one or more strategies after consultation. The study's primary outcome was the live birth rate (LBR) per woman after one double versus two sequential single embryo transfers. Results: Overall, 296 women underwent 362 embryo transfer cycles (D-FBT=186; SS-FBT=176). When adjusted for female age, the cumulative LBR per woman was similar in D-FBT (46.2%) and SS-FBT (58.2%) (p=0.054, aHR=1.62, 95% CI:1.00-2.60). While one monozygotic twin delivery was observed in the SS-FBT group, 22 of 86 (25.6%) live births after D-FBT were twins. Discussion: Following a freeze-all cycle, SS-FBTs yielded similar live birth rates (LBR) as D-FBT in women aged over 35 years.