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TFC Team 2023

Live birth and multiple birth rates in women under age 38 by elective single embryo transfer (ESET) versus double embryo transfer (DET) in United States IVF clinics


OBJECTIVE:

To compare live birth and multiple birth rates for cycles using eSET versus DET among women under age 38.

DESIGN:

Retrospective cohort study.

MATERIALS AND METHODS:

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. Analysis was stratified based on total number (2, 3, 4+) of embryos available, defined as number of embryos transferred plus number cryopreserved. Rates of live birth per embryo transfer and multiple birth per delivery were calculated for the eSET and DET groups. Analysis was further stratified by patient age (<35, 35-37). Models were adjusted for day of transfer, infertility diagnosis, parity, prior ART cycles, number of oocytes retrieved, assisted hatching, and ICSI. Adjusted and unadjusted risk ratios for the association between eSET and outcomes were calculated using log-binomial models.

RESULTS:

There were 6,200 eSET cycles and 21,286 DET cycles analyzed for patient age <35 and 1,547 eSET cycles and 9,579 DET cycles for patient age 35-37. There was a marked reduction in multiple births with eSET compared to DET (1.7% versus 39.4% for age <35 and 1.7% versus 32.0% for age 35-37). Adjusted live birth rates were slightly higher with DET for age 35-37 and for age <35 with four or more embryos available for transfer but were similar for age <35 with two or three embryos available for transfer (Table).

CONCLUSION:

Although adjusted live birth rates tended to favor DET for patients aged 35-37, for patients <35 this was only seen when 4 or more embryos were available to transfer. Multiple birth rates were much lower with eSET for both age groups, supporting the recommendation for younger patients to transfer one embryo at a time.

eSET with 1 embryo frozen No. Live births Unadjusted live birth rate (%) DET with 0 embryos frozen No. Live births Unadjusted live birth rate (%) Relative Risk (RR) (95% CI) Adjusted relative risk (aRR) (95% CI)
<35 (n=769 transfers) 337 43.8 <35 (n=9007 transfers) 3708 41.2 1.06 (0.97-1.17) 0.95 (0.87-1.03)
35-37 (n=258) 82 31.8 35-37 (n=4637) 1593 34.3 0.92 (0.77-1.10) 0.81 (0.68-0.96)
eSET with 2 embryos frozen No. Live births Unadjusted live birth rate (%) DET with 1 embryo frozen No. Live births Unadjusted live birth rate (%) RR (95% CI) aRR (95% CI)
<35 (n=963) 491 51.0 <35 (n=2318) 1175 50.7 1.00 (0.93-1.08) 0.93 (0.86-1.00)
35-37 (n=302) 122 40.4 35-37 (n=1168) 544 46.6 0.87 (0.72-1.04) 0.81 (0.67-0.97)
eSET with 3 or more embryos frozen No. Live births Unadjusted live birth rate (%) DET with 2 or more embryos frozen No. Live births Unadjusted live birth rate (%) RR (95% CI) aRR (95% CI)
<35 (n=4468) 2349 52.6 <35 (n=9961) 5664 56.7 0.92 (0.89-0.96) 0.88 (0.84-0.91)
35-37 (n=987) 449 45.5 35-37 (n=3774) 1940 51.4 0.88 (0.81-0.96) 0.83 (0.76-0.91)

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