Getting vaccinated does not impact pregnancy rates but a study shows catching Covid can temporarily make it less likely a couple will conceive.
Researchers have confirmed that getting vaccinated won’t hurt your fertility but getting Covid can.
The United States study looked at 2126 couples and found there was no difference in conception rates when at least one member of the couple was vaccinated, compared to those who were unvaccinated.
However, there was a slightly lower chance of conception if the man had been infected with Covid within 60 days of the woman’s menstrual cycle, suggesting that getting Covid-19 could temporarily reduce male fertility.
The study was conducted by Boston University and funded by the National Institutes of Health in the United States. It was published in the American Journal of Epidemiology on Thursday.
“The findings provide reassurance that vaccination for couples seeking pregnancy does not appear to impair fertility,” NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development director Diana Bianchi said in a statement.
“They also provide information for physicians who counsel patients hoping to conceive.”
It comes as a separate NIH-funded study found Covid-19 vaccines could cause some small, temporary changes to the length of women’s menstrual cycles, but these were well within the range of normal variability.
For the fertility study, researchers looked at data from the Pregnancy Study Online, an internet-based resource of US and Canadian couples who are trying to get pregnant without fertility treatment.
The women were aged between 21 and 45 years old and were asked to complete a questionnaire about their income, education levels, lifestyle, reproductive and medical histories.
They were also asked whether they were vaccinated against Covid-19 and whether their male partners, who could also complete a similar questionnaire, had ever tested positive for the virus.
The women were followed up every eight weeks until they became pregnant or for up to 12 months if they did not.
About 73 per cent of the women had received at least one dose of a vaccine, mainly the Pfizer-BioNTech, Moderna or Johnson & Johnson vaccines. About 74 per cent of their male partners were also vaccinated.
The investigators found no major differences in conception rates per menstrual cycle between unvaccinated and vaccinated couples in which at least one partner had received at least one dose of the vaccine.
The findings add to support evidence from animal studies, studies of humans undergoing fertility treatment, and the Covid-19 vaccine trials, that there is no link between vaccination and lower fertility.
“Similarly, several studies have documented no appreciable association between Covid-19 vaccination and miscarriage risk,” the researchers wrote.
Results were similar when the investigators looked at other factors such as whether they had received one or two doses of a vaccine, the type of vaccine they received, how recently they were vaccinated, whether they were American or Canadian, whether they were health care workers , or they were couples without a history of infertility.
But among the couples in which the man had tested positive within 60 days, they were 18 per cent less likely to conceive during that cycle.
After 60 days, there did not seem to be any difference.
Fever is known to reduce sperm count and motility and it’s quite common to develop a fever during a Covid infection, which could explain the temporary decline in fertility.
Other possible explanations could be inflammation in the testes and nearby tissues and erectile dysfunction, which are all common after a Covid infection.
More research is needed but the researchers noted that vaccination could in fact help to avoid this short-term impact to fertility.