No, COVID-19 vaccines don't affect women's fertility

Some women are holding off on being vaccinated against COVID-19 because of concerns the jab could affect their fertility, at times taking to social media to voice their concerns.

Anti-vaccination campaigners appear to be fuelling these fears and misleading women into thinking the vaccine may affect their chance of getting pregnant now or in future, or increase their risk of a miscarriage.

But there is no research evidence to support these claims. The science shows COVID vaccines have no effect on fertility, do not impact the chance of a miscarriage, and are safe and effective while pregnant.

Read more: Should pregnant women have a COVID vaccine? The evidence says it's safe and effective

COVID-19, however, can cause severe disease in pregnant women. Currently one in six of the most critically ill COVID patients in the UK are unvaccinated pregnant women.

Where did the fertility myth come from?

Myths about the vaccine affecting fertility can be tracked back to websites in the United States, which highlighted a claim by a European doctor in December 2020, while the vaccine was in Phase 3 trials.

In a blog post which has since been deleted, he hypothesised there were proteins in the placenta which have similarities with the spike protein in the virus. He thought antibodies in the vaccines that block the spike protein might also attach to the placenta.

But the viral and placental proteins are not similar enough that we would expect this to happen; studies have now confirmed this.

Read more: Pregnant or worried about infertility? Get vaccinated against COVID-19

What else does the science say?

Since the vaccine rollout began, six billion doses of COVID vaccines have been administered around the world, including Pfizer and Moderna, the recommended vaccines in Australia for under-60s, including pregnant women. Pfizer is the only vaccine offered in New Zealand.

There has not been a concurrent epidemic of infertility nor miscarriage.

Several populations of women have been followed up after vaccination. Women who have received COVID vaccinations have no difference in markers of ovarian follicle (egg) quality compared to unvaccinated women.

Studies have demonstrated no difference in embryo implantation rate for women who had received vaccination against COVID prior to having in vitro fertilisation (IVF) compared to unvaccinated women.

Studies have also looked for an effect of the vaccine on male fertility. These have demonstrated no change in sperm volume, concentration, motility (the ability to swim the right way) and total motile sperm count when comparing samples taken before and after COVID vaccination.

Read more: COVID-19 could cause male infertility and sexual dysfunction – but vaccines do not

What about in pregnancy?

Studies have also looked specifically at miscarriage. If antibodies against the spike did cause problems for the placenta, we would expect to see miscarriages. This is not the case.

The science is also clear the vaccine is safe in pregnancy. In studies of pregnant women in Canada and the United States who received the vaccine, minor side effects were similar to non-pregnant adults, and pregnancy complications and baby outcomes were similar to the background rate.

Research has shown there’s additional benefit of vaccination in pregnancy, with the baby gaining some protection against COVID. Antibodies have been found in cord blood and in breastmilk, suggesting temporary protection for babies (called passive immunity).

Getting vaccinated at any stage of pregnancy will provide this additional benefit.

What about future fertility?

The COVID vaccine – like every other vaccine you received during childhood, and like the flu vaccine that you get every flu season – induces your body to create an immune response. The components of the vaccine itself are broken down by the body within hours.

In other words, COVID vaccines don’t stay in your body. After vaccination, you are left with antibodies ready to act in case you get exposed to the COVID virus in the future. There is no link with infertility or miscarriage.

Read more: No, COVID vaccines don't stay in your body for years

Women who are pregnant, planning a pregnancy or are concerned about their future fertility might still have concerns or questions about getting a COVID vaccination. If this is you, talk to your own doctor or midwife who can discuss the science with you and answer any questions in a non-judgemental way.

Dr Erena Browne, Registrar in O&G at Auckland District Health Board, co-authored this article.