COVID-19, pregnancy, fertility and vaccines: Your questions answered

September 9, 2021


In our latest expert webinar, Professor Emma Duncan, professor of clinical endocrinology at King’s College London was joined by Professor Laura Magee, an obstetric physician specialising in medical problems during pregnancy.  

They took a look at the evidence around COVID-19 infection and COVID-19 vaccination in pregnancy and whether vaccines can affect fertility.


Does the COVID-19 vaccine affect fertility?

Despite the misinformation circulating online, there is no evidence that COVID vaccines affect the fertility of women.  

This misinformation may have first started because an important protein in the development of the placenta (Syncytin-1) has some similarities to the spike protein on the surface of the SARS-CoV-2 virus that causes COVID-19.  

“A false claim was made that the antibodies the vaccine would generate might also be directed towards the placenta,” Laura says.

However, since then, there have been many detailed studies comparing the structures of the Syncitin and spike proteins. While some parts of the structures do look the same, they’re no more similar than many other proteins found in our bodies, so it’s highly unlikely that there would be a biological effect. What’s more, there is  no evidence so far to show that COVID vaccines can interfere with fertility.

“Even though pregnant women were not planned to be part of the initial vaccine trials, we  learned a lot from accidental and unplanned pregnancies that happened within these trials,” Laura says.

Reassuringly, there was no difference in the rate of accidental pregnancies in the group who got the vaccine and those who received a dummy (placebo) jab, strongly suggesting there is no impact on fertility.

Researchers are also looking into whether COVID-19 infection itself might affect fertility.

The pandemic has been a challenging time for couples seeking fertility support because many fertility units had to close at certain points or became more limited in the services they have been able to offer. However, for those individuals who were able to access fertility support, there does not seem to have been any effect from the pandemic.  

A large study from Italy looked at data from fertility treatment units and found that the outcomes of fertility treatments for couples were just as good after the pandemic started, as before.  

Some people may also wonder about vaccines and male fertility.  This has been studied and there is no evidence that sperm counts, motility or fertility are affected by vaccination. 

Is COVID-19 a risk while pregnant?

While everyone who is pregnant hopes for a healthy outcome, this doesn’t always happen.

“It’s important for everyone to be aware that up to 20% of recognised pregnancies - one in five - end in a miscarriage, even if the person who is pregnant is fit and well,” explains Laura.

There have been some reports of women suffering a miscarriage in their first trimester, just after catching COVID-19. However, while this is concerning, COVID-19 and miscarriage are both common, therefore they may occur together by chance alone.

A review of recent studies showed that there is no increased risk of pregnancy loss in the first trimester in women with COVID-19, compared with those without. However, this changes later on in pregnancy.  A large UK study of hospital data found that having COVID near the time of birth increased the chances of the mother having problems with their blood pressure, giving birth early, needing a cesarean  birth, and of their baby needing some neonatal (newborn) care.

“While the risk of the tragedy of stillbirth remains low - less than 1 in 100 births - catching COVID near your due date doubles the risk of stillbirth above the background risk - which tragically is 3 to 4 births out of 1000 for pregnant women who are COVID-negative population,” cautions Laura.

Also, we also know that women from certain minority ethnic group backgrounds – such as Black or Asian women - are at higher risk of developing severe COVID-19 infection when not pregnant; and the chances of contracting severe COVID in pregnancy and having these complications follow this same trend

Are COVID-19 vaccines safe in pregnancy and how well do they work?

There is a long, established history of giving vaccines during pregnancy, including for infections, such as whooping cough and flu.

In the UK, advice for vaccination during pregnancy comes from different bodies of medical, nursing and midwifery experts, including The British Fertility Society, The Royal College of Obstetricians and Gynaecologists, and The Royal College of Midwives.

Another key source of expertise is the UK Teratology Information Service (teratology is the study of birth defects) which studies the safety of drugs, vaccinations and exposure to other things during pregnancy.

These organisations and others, have come together in discussion and together, they recommend COVID vaccination in pregnancy. Also, they advise that all women of reproductive age be offered and encouraged to have the vaccine.

“There’s no evidence that having the COVID vaccine during pregnancy increases the risk of stillbirth, early birth or smaller birth weight. This data are very reassuring and are accumulating rapidly, from thousands of pregnant women who have had their jabs in the UK,” Laura explains.

“Thinking about all types of vaccines – whether for COVID or for any other infection - the only type of vaccine that we do not give during pregnancy is one containing a ‘live’ virus- and none of the COVID vaccines are of this kind,” she adds.

Similarly a study looking into pregnant women who received an mRNA COVID-19 vaccine before conceiving or within the first 20 weeks of their pregnancy, found that getting the vaccine is not associated with an increased risk of miscarriage.

As well as being safe, we know that COVID vaccines are also effective for pregnant women.

“We know that there are changes to the immune system in pregnancy, but people seem to respond to vaccines in the same way during pregnancy as they would outside of pregnancy,” says Laura.  This issue is being studied in detail. 

While protective antibodies produced by the mother’s immune system in response to a vaccine can cross the placenta to help build immunity in the baby, the COVID vaccine itself does not cross the placenta, as it’s broken down within the arm muscle where it’s injected.

When is the best time to get a COVID-19 vaccine if I’m pregnant?

“I would actively encourage any woman to get vaccinated while planning pregnancy and at any point during pregnancy or during breastfeeding,” says Laura.  “What we do know is that for those women who have had their vaccine during the early stages of pregnancy, there has been no increased risk of miscarriage or other concerns.” Emma adds “women who catch COVID-19 in their third trimester are also more likely to have severe COVID and to need hospital, as well as all the potential complications this causes”. 

The Royal College of Obstetricians and Gynaecologists recognises that some people may feel uncertain about being vaccinated in the first trimester of pregnancy, and may want to wait until 14 weeks of pregnancy (the end of the first trimester) to receive their first jab.  However, women can catch COVID at any time during their pregnancy, so waiting to get a jab means that they might not have the best possible chance of preventing severe infection.  

“It’s most important to look after yourself during pregnancy and prepare by keeping as healthy as possible,” says Laura.

“It takes a total of 10 weeks from your first jab to be fully protected. Currently you’ll have to wait eight weeks between your first and second dose, plus it takes another two weeks after your second dose to be best protected.”

Is it safe to breastfeed after having a COVID-19 vaccine?

Everything we know so far shows that it’s safe to breastfeed after having a COVID-19 vaccine. In fact, it’s likely to be beneficial, by passing on protection from the virus to your child.

Researchers have found that people who are vaccinated during pregnancy do pass protective antibodies on to their baby through the umbilical cord and breast milk, with more studies under way.

Early breast milk, called colostrum, is particularly rich in antibodies. Where possible, women who decide to breastfeed are encouraged to give their babies this early milk to help give their baby’s immune system a head start.

“This advice stays the same and is particularly important with COVID still around,” says Laura. “If you are vaccinated and able to breastfeed, you’ll pass on those antibodies to your baby, which will help protect them from infection.”

Be part of vital COVID-19 research

Over the course of the pandemic, daily health reports and vaccine logs from our million-strong ZOE COVID Study contributors have played a vital role in understanding this new disease and how it affects us.

We’ll soon be launching a new study looking at the experience of women who are trying to conceive, are currently pregnant or have been pregnant during the course of the pandemic.  

Together with our research colleagues at King’s College London, we’ll be exploring a number of things, including the outcomes of any pregnancies and what healthcare has been like for people planning and having babies during the pandemic.

If you’re interested in taking part, and haven't already, simply download the ZOE COVID Study and keep an eye out for more details coming soon.  

Additional links for COVID-19 and women’s health

Please note these links will take you to an external website and redirect you away from the ZOE COVID Study. 

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