Implementation of Only Blastocyst Stage Embryo Transfers Among All Age Groups of Patients UndergoingIn Vitro Fertilization (IVF) Treatment Cycles: An Approach to Improve IVF Outcome

Objective To evaluate IVF treatment cycle outcomes before and after implementing only blastocyst stage embryo transfers among patients of all age groups. Design IRB approved retrospective study at an academic hospital based IVF clinic. Materials and Methods After controlled ovarian hyper-stimulation and fertilization in vitro, zygotes produced were cultured under standard embryo culture conditions. Under ultrasound guidance, Day 3 or Day 5 embryos were transferred in appropriately prepared uterus. Our study included 2874 patients of all age groups from two different time periods (P1 = 1/1/2007-9/5/2014; P2=9/6/2014-12/31/2017). During P2, all patients regardless of their age, diagnosis, and number of embryo(s) in culture were offered embryo transfer only at blastocyst stage. Also, patients having only morulae and/or early blastocysts did not have embryo transfer during P2. These slow developing embryos were cultured to D6 and were cryopreserved if developed to more advanced stage. Patients using donor gametes, testicular/epididymal sperm, or undergoing preimplantation genetic testing (PGT) were excluded from this study. Means and standard deviations were computed for continuous measures and frequency distributions for categorical variables. For univariable comparisons of study groups (day-3 transfers vs. day-5 transfers), Pearson's chi-squared test was used to compare study groups on categorical outcomes. T-tests were used to compare study groups on continuous outcomes. Results P-1P-2P-ValueNumber of Retrievals2121753−Number of Transfers2016508−D3 (%)64.74.1D5 (%)35.395.9Mean (±SD) patient age35.0±4.735.3±4.20.18Mean (±SD) embryos transferred2.1±1.11.3±0.5 Conclusions 1) Transfer of only blastocyst stage embryo(s) in patients of all ages may result in high ongoing pregnancy rate even with fewer number of embryos transferred. 2) Ongoing multiple gestation rate may be reduced among patients of all age groups by transferring only blastocyst stage embryo(s). 3) Transfer of only blastocyst stage embryos allowed us to select embryos with better implantation potential, perform more eSETs and not transfer embryos evaluated with less prognostic value. 4) Transfer of only blastocyst stage embryo(s) may be a less invasive yet effective strategy to improve IVF outcomes. Disclosures Nothing to disclose. Funding None.