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Some reproductive-aged individuals remain unvaccinated against COVID-19 due to concerns about potential adverse effects on fertility. We examined the associations of COVID-19 vaccination and SARS-CoV-2 infection with fertility among couples trying to conceive spontaneously using data from an internet-based preconception cohort study. We enrolled 2,126 self-identified females residing in the U.S. or Canada during December 2020-September 2021 and followed them through November 2021. Participants completed questionnaires every 8 weeks on sociodemographics, lifestyle, medical factors, and partner information. We fit proportional probabilities regression models to estimate associations between self-reported COVID-19 vaccination and SARS-CoV-2 infection in both partners with fecundability, the per-cycle probability of conception, adjusting for potential confounders. COVID-19 vaccination was not appreciably associated with fecundability in either partner (female FR=1.08, 95% CI: 0.95, 1.23; male FR=0.95, 95% CI: 0.83, 1.10). Female SARS-CoV-2 infection was not strongly associated with fecundability (FR=1.07, 95% CI: 0.87, 1.31). Male infection was associated with a transient reduction in fecundability (FR=0.82, 95% CI: 0.47, 1.45 for infection within 60 days; FR=1.16, 95% CI: 0.92, 1.47 for infection >60 days). These findings indicate that male SARS-CoV-2 infection may be associated with a short-term decline in fertility and that COVID-19 vaccination does not impair fertility in either partner.

Background There is a well-documented decline in fertility treatment success with increasing female age; however, there are few preconception cohort studies examining female age and natural fertility. In addition, data on male age and fertility is inconsistent. Given the increasing number of couples attempting conception at older ages, a more detailed characterization of age-related fecundability in the general population is of great clinical utility. Objective To examine the association between female and male age with fecundability. Study Design We conducted a web-based preconception cohort study of pregnancy planners from the United States and Canada. Participants enrolled between June 2013 and July 2017. Eligible participants were aged 21–45 years (females) or ≥21 years (males), and not using fertility treatments. Couples were followed until pregnancy or for up to 12 menstrual cycles. We analyzed data from 2,962 couples who had been trying to conceive for ≤3 cycles at study entry and reported no history of infertility. We used life-table methods to estimate the unadjusted cumulative pregnancy proportion at 6 and 12 cycles by female and male age. We used proportional probabilities regression models to estimate fecundability ratios, the per-cycle probability of conception for each age category relative to the referent (21–24 years), and 95% confidence intervals. Results Among females, the unadjusted cumulative pregnancy proportion at 6 cycles of attempt time ranged from 62.0% (age 28–30 years) to 27.6% (age 40–45 years); the cumulative pregnancy proportion at 12 cycles of attempt time ranged from 79.3% (age 25–27 years) to 55.5% (age 40–45 years). Similar patterns were observed among males, although differences between age groups were smaller. After adjusting for potential confounders, we observed a nearly monotonic decline in fecundability with increasing female age, with the exception of 28–33 years, where fecundability was relatively stable. Fecundability ratios were 0.91 (95% confidence interval: 0.74–1.11) for ages 25–27, 0.88 (95% confidence interval: 0.72–1.08) for ages 28–30, 0.87 (95% confidence interval: 0.70–1.08) for ages 31–33, 0.82 (95% confidence interval: 0.64–1.05) for ages 34–36, 0.60 (95% confidence interval: 0.44–0.81) for ages 37–39, and 0.40 (95% confidence interval: 0.22–0.73) for ages 40–45, compared with the reference group (ages 21–24 years). The association was stronger among nulligravid women. Male age was not appreciably associated with fecundability after adjustment for female age, although the number of men over age 45 years was small (n=37). Conclusion In this preconception cohort study of North American pregnancy planners, increasing female age was associated with an approximately linear decline in fecundability. While we found little association between male age and fecundability, the small number of men in our study over age 45 years limited our ability to draw conclusions on fecundability in older men.

Sugar-sweetened beverages, particularly sodas and energy drinks, were associated with lower fecundability, but diet soda and fruit juice had little association.

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