Elective transfer of one embryo is associated with a higher cumulative live birth rate and improved perinatal outcomes compared to the transfer of two embryos with in vitro fertilization

Assisted Reproduction

VOLUME 2, ISSUE 1, P50-57, MARCH 01, 2021


Rachel B. Mejia, D.O., Emily A. Capper, B.A., Karen M. Summers, M.P.H., Patrick Ten Eyck, Ph.D., Bradley J. Van Voorhis, M.D.



To compare the effects of initial elective single embryo transfer (ieSET) and initial double embryo transfer (iDET) strategies on the cumulative live birth rate (CLBR) and perinatal outcomes after IVF.


Retrospective cohort study.


Society for Assisted Reproductive Technology (SART) reporting clinics.


49,333 patients with initial oocyte retrievals between January 2014 and December 2015.



Main Outcome Measure(s)

The primary outcome was CLBR, defined as up to 1 live birth resulting from a retrieval cycle and linked transfer cycles. Secondary outcomes included cycles to pregnancy, multifetal delivery rate, infant birthweight, and perinatal mortality rate.


Compared to iDET, ieSET was associated with increased CLBR (74% vs. 57%; adjusted odds ratio [AOR], 1.32; 95% CI, 1.26–1.38). When stratified by age, the same trend was seen in all age categories, with statistical significance for those <38 years of age. ieSET was associated with reduced multifetal delivery (8% vs. 34%; AOR, 0.13; 95% CI, 0.12–0.14), increased birthweight (mean difference, 406 grams; 95% CI, 387–425), reduced preterm births (1.2% vs. 2.8%), and reduced perinatal mortality (0.5% vs. 1.2%). Compared with iDET, ieSET was associated with slightly more embryo transfer cycles (1.7 vs. 1.4 cycles; AOR, 1.19; 95% CI, 1.16–1.21) to achieve a pregnancy resulting in live birth.


The association of ieSET with a higher CLBR and markedly improved perinatal outcomes outweigh the relatively minor increase in time to pregnancy, reinforcing the guidance for eSET in initial transfer cycles, particularly in younger patients with a good prognosis.