COVID-19 vaccination does not reduce chances of conception, study suggests

News release

Thursday 20 January 2022

NIH-funded research shows that infection can affect male fertility.

COVID-19 vaccination does not affect the chances of conceiving a child, according to a study of more than 2,000 couples funded by the National Institutes of Health. Researchers found no differences in the chances of conception if either male or female partner was vaccinated, compared to unvaccinated couples. However, married couples had a slightly lower chance of conception if the male partner was infected with SARS-CoV-2 within 60 days before a menstrual cycle, suggesting that COVID-19 may temporarily reduce male fertility. The study was conducted by Amelia K. Wesselink, Ph.D., of Boston University, and colleagues. It appears in the American Journal of Epidemiology.

“The findings provide reassurance that vaccination for couples seeking pregnancy does not appear to impair fertility,” said Diana Bianchi, MD, director of NIH’s. Eunice Kennedy Shriver National Institute of Child Health and Human Development, which funded the study. “They also provide information for doctors counseling patients hoping to conceive.”

Researchers analyzed data from the Pregnancy Study Online (PRESTO), an Internet-based prospective cohort study of American and Canadian couples trying to conceive without fertility treatment. PRESTO is led by Lauren A. Wise, Sc.D., of Boston University.

Study participants were identified as female and were 21 to 45 years old. They completed a questionnaire about their income and education levels, lifestyle, and reproductive and medical history, including whether or not they had been vaccinated against COVID-19 and whether they or their partners had ever tested positive for SARS-CoV-2. They also invited their male partners aged 21 or over to complete a similar questionnaire. Female partners completed follow-up questionnaires every eight weeks until they became pregnant, or up to 12 months if they did not.

The researchers found no major differences in conception rates per menstrual cycle between unvaccinated and vaccinated couples in which at least one partner received at least one dose of the vaccine.

Results were similar when the researchers looked at factors that might affect the results, such as whether study participants or their partners received one or two doses of a vaccine, the type of vaccine they received, how recently they were vaccinated, whether they was american. or Canadian, or they were health care workers, or they were couples without a history of infertility.

Overall, testing positive for SARS-CoV-2 infection was not associated with a difference in conception. Couples in which the male partner tested positive within 60 days of a given cycle were 18% less likely to conceive in that cycle. There was no difference in conception rates for couples in which the male partner tested positive more than 60 days before a cycle compared to couples in which the male partner did not test positive.

Fever, which is known to reduce sperm count and motility, is common during SARS-CoV-2 infection and may therefore explain the temporary decline in fertility the researchers observed in couples in which the male partner had a recent infection. Other possible reasons for a decline in fertility among male partners who have recently tested positive may be inflammation in the testes and nearby tissues and erectile dysfunction, all common after SARS-CoV-2 infection. The researchers noted that this short-term decline in male fertility could potentially be avoided by vaccination.

The researchers concluded that their results suggest that vaccination against COVID-19 has no harmful association with fertility. Vaccination against COVID-19 can also help prevent the risks that SARS-CoV-2 infection poses to maternal and fetal health.

Over the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): NICHD leads research and education to understand human development, improve reproductive health, improve the lives of children and adolescents, and optimize capabilities for all. For more information, visit https://www.nichd.nih.gov.

About the National Institutes of Health (NIH):NIH, the nation’s medical research agency, includes 27 institutes and centers and is a component of the US Department of Health and Human Services. NIH is the primary federal agency that conducts and supports basic, clinical, and translational medical research, investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

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