title: Elective single blastocyst transfer in advanced maternal age.
abstract: OBJECTIVE
  The purpose of this study was to investigate reproductive outcomes following elective single blastocyst transfer (eSBT) compared with those of double blastocyst transfer (DBT) in advanced maternal age.
  
  
  METHODS
  This was a retrospective cohort study performed at an academic fertility center. All women aged 40 and over for whom in vitro fertilization (IVF) cycles were performed and in whom embryo culture was extended to the blastocyst stage were reviewed for possible inclusion. Exclusion criteria included the following: women with >3 previous IVF cycles, the use of donor or frozen oocytes, preimplantation genetic diagnosis/preimplantation genetic screening cycles, and cycles in which embryos did not reach the blastocyst stage on day 5. The study included 310 women; 148 were included in the eSBT group and 162 were included in the DBT group. Live birth rate (LBR) was the main outcome. Outcomes were analyzed using logistic regression, controlling for confounders. These confounders were embryo expansion, embryo quality, and the number of previous IVF cycles.
  
  
  RESULTS
  The mean age of the whole group was 41 ± 0.91 years, and the LBR was 21.6%. The eSBT group and the DBT group achieved similar clinical pregnancy rates (33 vs. 33%) (OR 1.04; 95%CI, 0.62-1.75) and LBRs (20 vs. 22.8%) (OR 1.43; 95% CI, 0.78-2.64). The multiple birth rate was lower in the eSBT group (0 vs. 16%, p = 0.02). The subgroup of women who had elective DBT (eDBT) achieved a higher LBR (20 vs. 30.6%) (OR 2.32; 95% CI, 1.16-4.68) and a higher multiple birth rate (0 vs. 22%, p = 0.001). Cycles with early blastocyst transfers were associated with lower LBRs compared with cycles with fully expanded blastocyst transfers (11 vs. 24%, p = 0.02).
  
  
  CONCLUSIONS
  The results of this study indicate that eSBT is associated with similar LBRs compared to the entire DBT cohort; however, when supernumerary blastocysts are available for cryopreservation, eDBT is associated with both higher LBRs and a higher number of multiple births. Studies assessing the cumulative LBR in advanced maternal age after single blastocyst transfer and subsequent frozen-thawed blastocyst transfers are needed.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, McGill University Health Center, Royal Victoria hospital, 687 Pine Avenue West, Montreal, Quebec, H3A 1A1, Canada. sr.tannus@gmail.com.
authors.forename: Samer
authors.initials: S
authors.lastname: Tannus
authors.affiliation: Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, McGill University Health Center, Royal Victoria hospital, 687 Pine Avenue West, Montreal, Quebec, H3A 1A1, Canada.
authors.forename: Weon-Young
authors.initials: WY
authors.lastname: Son
authors.affiliation: Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, McGill University Health Center, Royal Victoria hospital, 687 Pine Avenue West, Montreal, Quebec, H3A 1A1, Canada.
authors.forename: Michael Haim
authors.initials: MH
authors.lastname: Dahan
mesh_terms: D000328:Adult; D001723:Birth Rate; D001755:Blastocyst / Q000502:physiology*; D015925:Cryopreservation; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D050498:Live Birth; D008423:Maternal Age; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple; D019836:Preimplantation Diagnosis
keywords: Advanced maternal age; Elective single blastocyst transfer; Live birth rate; Multiple birth rate