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. 2022 Oct 3;5(10):e2236609.
doi: 10.1001/jamanetworkopen.2022.36609.

Association Between Time Interval from COVID-19 Vaccination to In Vitro Fertilization and Pregnancy Rate After Fresh Embryo Transfer

Wenhao Shi  1 , Min Wang  1 , Xia Xue  1 , Na Li  1 , Lijuan Chen  1 , Juanzi Shi  1
Affiliations

Association Between Time Interval from COVID-19 Vaccination to In Vitro Fertilization and Pregnancy Rate After Fresh Embryo Transfer

Wenhao Shi et al. JAMA Netw Open. .

Abstract

Importance: There is a lack of information regarding the need to postpone conception after COVID-19 vaccination.

Objective: To investigate the time interval between the first dose of inactivated COVID-19 vaccine and in vitro fertilization (IVF) treatment as well as the rate of pregnancy after a fresh embryo transfer.

Design, setting, and participants: This cohort study was conducted at a single public IVF center in China. Female patients aged 20 to 47 years and undergoing IVF treatment were consecutively registered from May 1 to December 22, 2021, with follow-up until March 31, 2022. Patients with SARS-CoV-2 infection before or during IVF treatment and those who underwent 2 or more IVF treatments, received the noninactivated or unknown COVID-19 vaccine, or did not have a fresh embryo transfer were excluded from this study.

Exposures: The vaccinated group (subdivided into 4 subgroups of time interval from first vaccination to fertilization treatment: ≤30 days, 31-60 days, 61-90 days, and ≥91 days) and nonvaccinated group.

Main outcomes and measures: Risk ratios (RRs) for the association between the time interval and ongoing pregnancy (pregnancy continued at least 12 weeks).

Results: A total of 3052 female patients (mean [SD] age, 31.45 [3.96] years) undergoing IVF treatment were analyzed in this study. There were 667 vaccinated patients receiving IVF (35 were vaccinated ≤30 days, 58 were vaccinated 31-60 days, 105 were vaccinated 61-90 days, and 469 were vaccinated ≥91 days before fertilization treatment), and 2385 unvaccinated patients receiving treatment. The ovarian stimulation and laboratory parameters were similar among all groups. Ongoing pregnancy was significantly lower in the 30 days or less subgroup (34.3% [12 of 35]; adjusted RR [aRR], 0.61; 95% CI, 0.33-0.91) and the 31 to 60 days' subgroup (36.2% [21 of 58]; aRR, 0.63; 95% CI, 0.42-0.85). A slightly but not statistically lower rate was found in the 61 to 90 days' subgroup, and no reduced risk for ongoing pregnancy in the 91 days or more subgroup was observed (56.3% [264 of 469]; aRR, 0.96; 95% CI, 0.88-1.04) compared with the unvaccinated group (60.3% [1439 of 2385], as reference).

Conclusions and relevance: Findings of this study suggest that receipt of the first inactivated COVID-19 vaccine dose 60 days or less before fertilization treatment is associated with a reduced rate of pregnancy. In patients undergoing IVF treatment with a fresh embryo transfer, the procedure may need to be delayed until at least 61 days after COVID-19 vaccination.

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Conflict of interest statement

Conflict of Interest Disclosures: None reported.

Figures

Figure 1.
Figure 1.. Data Processing
IVF indicates in vitro fertilization. aSome patients met more than 1 criterion for exclusion.
Figure 2.
Figure 2.. Follicle, Oocyte, and Embryo Performance
Data were adjusted for female age (smooth), body mass index, etiological factors of infertility, stimulation protocol, and primary infertility.
Figure 3.
Figure 3.. Stratified Analyses of Ongoing Pregnancy Rate With Different Time Intervals Between the First Dose of COVID-19 Vaccine and In Vitro Fertilization (IVF) Treatment
Data were adjusted for female age, antral follicle count, etiological factors of infertility, stimulation protocol, embryo stage at transfer, and number of embryo transfers. Unvaccinated cycles were used as a reference (risk ratio [RR] = 1), and an RR less than 1 indicates a reduced ongoing pregnancy rate. GnRH indicates gonadotropin-releasing hormone.
Figure 4.
Figure 4.. Ongoing Pregnancy Rate by Time Interval of Vaccination to Fertilization Treatment as a Continuous Variable
The horizontal axis represents the time interval between vaccination and in vitro fertilization (days, as a continuous variable), and the vertical axis represents the ongoing pregnancy rate. Spline smoothing plot represents the ongoing pregnancy rate according to the time interval of vaccination to fertilization treatment. The model was adjusted for female age (smooth), antral follicle count, etiological factors of infertility, stimulation protocol, embryo stage at transfer, and number of embryo transfers. The shaded areas represent the 95% CIs, and the marks along the x axis represent the distribution of participants in the study.
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