Impact of coronavirus disease 2019 vaccination on live birth rates after in vitro fertilization

Abstract

Objective: To investigate coronavirus disease 2019 (COVID-19) vaccination on the live birth rates in patients who underwent in vitro fertilization.

Design: Retrospective cohort study.

Setting: Academic fertility practice.

Patient(s): Patients who underwent fresh or frozen embryo transfer cycles at an academic center between January 1, 2020, and December 31, 2021.

Intervention(s): Coronavirus disease 2019 vaccination, defined as completing a 2-dose regimen (Pfizer or Moderna) or 1-dose regimen (Johnson & Johnson/Janssen) before cycle initiation.

Main outcome measure(s): The primary outcome was the live birth rate per embryo transfer. The secondary outcomes included positive human chorionic gonadotropin (hCG) and clinical pregnancy rates per embryo transfer. The outcomes from cycles among vaccinated and unvaccinated patients were compared. Descriptive statistics were used to analyze demographic and cycle characteristics using the Student t test and Wilcoxon rank sum, Pearson chi-square, and Fisher exact tests as appropriate for univariate analysis. Generalized estimating equation models were used to examine the strength of the relationship between vaccination status and pregnancy outcomes.

Result(s): Among 709 unvaccinated and 648 vaccinated fresh cycles, no statistically significant differences were observed between the number of oocytes retrieved, oocyte maturity, fertilization, and blastocyst utilization rates. In the adjusted multivariate analysis, no statistically significant differences were noted between fresh cycles among vaccinated patients compared with those among unvaccinated patients with the rates of positive hCG (adjusted odds ratio [aOR], 1.37; 95% confidence interval [CI], 0.84-2.25), clinical pregnancy (aOR, 1.22; 95% CI, 0.73-2.03), or live birth (aOR, 1.37; 95% CI, 0.79-2.25) per embryo transfer. Among 264 unvaccinated and 423 vaccinated frozen embryo transfer (FET) cycles, vaccinated patients had higher odds of positive hCG (aOR, 1.54; 95% CI, 1.08-2.20), clinical pregnancy (aOR, 1.80; 95% CI, 1.27-2.56), and live birth (aOR, 2.31; 95% CI, 1.60-3.32) per embryo transfer than unvaccinated patients.

Conclusion(s): Patients who were COVID-19 vaccinated before FET had higher rates of biochemical pregnancy, clinical pregnancy, and live birth. Vaccination was not associated with the pregnancy or live birth rates after fresh cycles. This study contributes to evidence supporting COVID-19 vaccination for patients attempting pregnancy.

Keywords: COVID-19; in vitro fertilization; live birth; vaccination.