Embryo transfers performed during daylight savings time led to reduced live birth rates in older patients

To study the impact of undergoing an embryo transfer during the week of daylight savings time transition on live birth rates.

We performed a retrospective observational cohort study of patients undergoing embryo transfer at an academic infertility practice during the week of spring or fall daylight savings time transition (cases), or the 2 weeks preceding and following the daylight savings transition (controls) between 2015 and 2021. The primary exposure was completion of an embryo transfer during the week of daylight savings time transition. The primary outcome was a comparison of live birth rate per embryo transfer among individuals undergoing an embryo transfer during the week of daylight savings time (DST) transition and those who did not.

A total of 309 embryo transfers occurred during the week of daylight savings transition and 1242 embryo transfers occurred in the control group outside of the daylight savings transition week. The live birth rate after embryo transfer during DST transition weeks was 39.2% (121/309) compared to 40.8% (507/1242) (p = 0.59). When restricting the analysis to individuals (age > 37 years), the live birth rate after embryo transfer during DST transition week was 23.5% (24/102) compared to 34.8% (149/429) (p = 0.03). This difference persisted in the mixed-effects regression model demonstrating that after adjusting for relevant covariates, embryo transfer during DST transition weeks resulted in a 45% decrease in the odds of achieving a live birth.

Daylight savings time transition may be associated with less favorable outcomes after embryo transfer among an older infertile patient population. Future work is needed to prospectively examine the influence of circadian rhythm disruption on reproductive outcomes.