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Elective single embryo transfer in women under age 38 reduces multiple birth rates but not live birth rates in United States fertility clinics


To determine the effect of elective single embryo transfer (eSET) rates on live birth rates and multiple birth rates in United States IVF clinics.


Retrospective cohort study.


Data were collected on all autologous fresh IVF cycles performed in 2013 and reported to the National Assisted Reproductive Technology Surveillance System (NASS). Cycles using preimplantation genetic diagnosis or screening were excluded. The analysis was stratified by patient age (<35 and 35-37). Clinics were divided into groups based on eSET rates: 0-9%, 10-19%, 20-29%, 30-39%, 40-49%, >=50% for age <35 and 0-9%, 10-19%, 20-29%, >=30% for age 35-37. Aggregate rates of live birth per embryo transfer and multiple birth per delivery were calculated for each eSET group after controlling for significant confounding variables (number of cycles per year, ICSI rate, blastocyst versus cleavage stage embryo transfer, average patient age, number of prior ART cycles, parity, race).


464 clinics were analyzed for the age <35 group and 450 clinics for the age 35-37 group. There was a linear decrease in multiple birth rate with increasing eSET rate and no significant difference in clinic-level live birth rates (Table). Clinics with a higher average eSET rate tended to perform more blastocyst embryo transfers (day 5-6 of culture) and had higher average embryo implantation rates.


Our study showed a marked and linear reduction in multiple birth rates and importantly, little to no effect on live birth rates with increasing rates of eSET. This study supports the growing evidence that eSET is effective in decreasing the high multiple birth rates associated with IVF and suggests eSET should be utilized more frequently than is currently practiced.

Live birth rates and multiple birth rates by clinic elective single embryo transfer rate
Clinic eSET rate (Age <35) 0-9% 10-19% 20-29% 30-39% 40-49% >=50% P-value
Number of clinics 219 96 55 41 17 36
Live birth rate (%) 45.2 49.6 48.0 48.1 43.8 44.5 0.10
Multiple birth rate (%) 37.5 33.2 28.6 27.3 16.3 15.2 <0.001
Clinic eSET rate (Age 35-37) 0-9% 10-19% 20-29% >=30% P-value
Number of clinics 331 61 29 29
Live birth rate (%) 38.4 35.1 32.4 41.3 0.14
Multiple birth rate (%) 29.8 22.1 19.7 18.5 <0.001

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