New Tommy’s research investigates link between COVID-19 and pregnancy complications

New study finds women infected with COVID-19 in later pregnancy are more likely to have birth-related complications.

A new study published in Nature Medicine journal has found a link between COVID-19 infections in pregnant women and pregnancy complications.  

The study, part-funded by Tommy’s and co-led by Dr Sarah Stock from the University of Edinburgh and Dr Rachael Wood Public Health Scotland, used healthcare data from across Scotland to investigate the impact of COVID-19 on pregnancy.  

Since the COVID-19 pandemic began in March 2020, pregnant women have been classed as an ‘at risk’ group with growing evidence suggesting they might be at increased risk of becoming severely unwell if infected, particularly in the third trimester. This can lead to further health complications for both mum and baby. 

The latest research from the Tommy’s-funded COVID-19 in Pregnancy Scotland (COPS) study, found women who catch COVID-19 towards the end of their pregnancy are more vulnerable to potential complications such as premature birth and stillbirth, further supporting the need for pregnant women to be protected against COVID-19. 

COPS was specifically set up to provide research and information on COVID-19 infection, vaccination and pregnancy. It does this by analysing the links between pregnancy health records in Scotland and the records of COVID-19 test results and vaccinations.  

What did we find? 

The study included over 87,000 women in Scotland who were pregnant between December 2020 and October 2021. 

From the data available, the team found that women who caught the virus towards the end of their pregnancy – 28 days or less before due date – were more likely to have complications than those who caught it in the earlier stages of their pregnancy, or not at all.  

Most of these cases were found to be women who hadn’t received a vaccine. Since the start of Scotland’s vaccination programme, 4,950 cases of COVID-19 have been confirmed during pregnancy with 77% of these in unvaccinated women.   

For women who contracted the virus within 28 days of labour, 17% gave birth prematurely (their babies were born more than 3 weeks before their due date) . This was double the Scottish premature birth rate (at 8%) for other women during the same study period.  

Sadly, the study also showed an increase in perinatal deaths in women who contracted COVID-19 within 28 days of giving birth – with 23 deaths per 1,000 births, compared to the background perinatal mortality rate in Scotland of 6 per 1,000. The experts stressed that it is not possible to say for certain if COVID-19 contributed directly to the deaths or preterm births as they did not have access to detailed clinical records for individual women. 

Unvaccinated pregnant women were also more likely to need hospital care with the research showing 98% of women admitted to critical care due to COVID-19 had not received any form of vaccination. It’s important to note that during the study period vaccine uptake was lower in pregnant women compared with women aged 18 – 44 in the general population. The RCOG and other public health bodies have since re-issued vaccination guidance to show the importance of vaccination for pregnant women.  

Why is this important? 

COPS co-lead Dr Sarah Stock, of the University of Edinburgh’s Usher Institute – who is also a consultant obstetrician - said: “Our data adds to the evidence that vaccination in pregnancy does not increase the risk of complications in pregnancy, but COVID-19 does.  

“COVID-19 vaccination in pregnancy is crucial to protect women and babies from preventable, life-threatening complications of the virus.” 

Research studies such as this are vital in our effort to save babies’ lives as they give us insight into the impact COVID-19 can have on mum and baby. This information helps to ensure we provide the best, and most up-to-date, care and advice to parents during pregnancy.  

Should I get vaccinated? 

Dr Sarah Stock, added:  

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“We know that complications from COVID-19 while pregnant can be serious for mothers and babies. It’s understandable that pregnant women may be anxious about getting the vaccine, but I hope that our results reassure mothers who are seeking to make informed choices for themselves and their babies. It should also give confidence to midwives, doctors, vaccinators and others who are in a position to support them in their decision.”

Kate Marsh, Tommy’s Midwifery Manager said:

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“There is no known risk with the COVID-19 vaccine during pregnancy or while breastfeeding and we know that the vaccines do not contain live coronavirus and cannot infect a pregnant woman or her unborn baby in the womb. It is completely understandable to be concerned about getting a vaccine during pregnancy, but you don’t have to make this decision alone. We would encourage all pregnant women to talk to their GP or midwife about the vaccination so they can make an individual decision about how to protect themselves.”

For more information and guidance on the COVID-19 vaccine during pregnancy, visit our PregnancyHub: The COVID-19 vaccine in pregnancy and breastfeeding | Tommy's (  

You can also watch our latest Covid-19 Q&A Instagram Story on @tommys_pregnancyhub.