Elective single embryo transfer in women less than age 38 years reduces multiple birth rates, but not live birth rates, in United States fertility clinics

Abstract

Objective: To determine the effect of elective single ET (eSET) on live birth and multiple birth rates by a cycle-level and clinic-level analysis.

Design: Retrospective cohort study.

Setting: Not applicable.

Patient(s): Patient ages <35 and 35-37 years old.

Intervention(s): None.

Main outcome measure(s): Clinics were divided into groups based on eSET rate for each age group and aggregate rates of live birth per ET and multiple birth per delivery were calculated. A cycle-level analysis comparing eSET and double ET (DET) live birth and multiple birth rates was also performed, stratified based on total number (2, 3, or 4+) of embryos available, embryo stage, and patient age.

Result(s): There was a linear decrease in multiple birth rate with increasing eSET rate and no significant difference in clinic-level live birth rates for each age group. Cycle-level analysis found slightly higher live birth rates with double ET, but this was mainly observed in women aged 35-37 years or with four or more embryos available for transfer, and confirmed the marked reduction in multiple births with eSET.

Conclusion(s): Our study showed a marked and linear reduction in multiple birth rates, and important, little to no effect on clinic-level live birth rates with increasing rates of eSET supporting the growing evidence that eSET is effective in decreasing the high multiple birth rates associated with IVF and suggests that eSET should be used more frequently than is currently practiced.

Keywords: Elective single embryo transfer; IVF; live birth rate; multiple birth rate.

FIGURE 1

Live birth rate and multiple birth rate by clinic elective single ET (eSET) rate for fresh IVF cycles in patients <35 years old, US fertility clinics, 2013. Estimated means with standard error bars for live birth rates and multiple birth rates after adjusting for significant confounding variables. Live birth rates for patient aged <35 years adjusted for blastocyst transfer rate. Multiple birth rates for patient aged <35 years adjusted for blastocyst transfer rate and parity.

FIGURE 2

Live birth rate and multiple birth rate by clinic elective single ET (eSET) rate for fresh IVF cycles in patients 35–37 years old, US fertility clinics, 2013. Estimated means with standard error bars for live birth rates and multiple birth rates after adjusting for significant confounding variables. Live birth rates for patient aged 35–37 years, adjusted for blastocyst transfer rate, intracytoplasmic sperm injection (ICSI) rate, and patient race. No significant confounding variables were found for multiple birth rates for ages 35–37 years.