You are currently using an unsupported browser which could affect the appearance and functionality of this website. Please consider upgrading to the latest version or using alternatives such as Mozilla Firefox, Google Chrome or Microsoft Edge.

Blog: Pregnancy and COVID-19 vaccines: why the messaging evolved

9 Mar 2022

Dr Jonathan Richardson, a Senior Medical Information Scientist at the UK Teratology Information Service (UKTIS), writes…

Since COVID-19 vaccines were first offered to pregnant women at the beginning of 2021, the decision about whether to have the vaccine has been difficult and confusing for many pregnant women. There have been lots of reasons for this, a swathe of misinformation online, changing Government guidance and women wanting to make sure the vaccine was safe for their baby.

Vaccines in pregnancy
As a Senior Medical Information Scientist, I have been involved in analysing the latest data around the use of the COVID-19 vaccine in pregnancy and would like to explain how and why the messaging on this has evolved.
I work for UKTIS, an organisation funded by the UK Health Security Agency to provide independent evidence-based advice and guidance to healthcare professionals and pregnant women in the NHS about the use of medicinal products, including medicines and vaccines.
In my role, I discuss vaccination in pregnancy with people from a wide variety of backgrounds, all with varying levels of health literacy. Many of the people I have spoken with don’t know how clinical experts make decisions about whether medicinal products can be used in pregnancy, or not.
Which is why I think it’s important to explain.
For the general, (non-pregnant) population the effectiveness of the medication and some basic information about its safety are provided from clinical trials that are conducted before a medicine or vaccine is approved for use.
Yet, because pregnant women are generally excluded from clinical trials, pre-clinical information is very rarely available for pregnant women. As a result, information about safety and effectiveness is collected using real-world data, which looks at people who have had the vaccine or medicine and seeing whether there were any adverse outcomes to consider. The main constraint of this approach is how long it takes for this information to be collected, particularly about safety.

COVID-19 vaccines in pregnancy

With the COVID-19 pandemic came new challenges. There was a need to analyse data at a rapid rate.

From early in the pandemic, it became apparent that pregnant women were at increased risk of severe COVID-19. Additionally, some pregnant women were at high risk of COVID-19 exposure due to their jobs and/or had pre-existing medical conditions that put them at even higher risk of severe illness.

When the vaccination programme was launched in December 2020, the initial advice from the Government’s Joint Committee on Vaccination and Immunisation (JCVI) was not to recommend the COVID-19 vaccine in pregnancy at all, because at that stage there wasn’t enough data available about what had happened to pregnant women who had received the vaccine.

This was largely due to pregnant women not being included in the vaccine clinical trials, despite the RCOG, Royal College of Midwives (RCM) and UKTIS calling for their inclusion from early on , along with real-world data and outcomes not yet being available.

While there was a data deficit at this time, UKTIS produced a review  of all the significant knowledge that has been collected for other non-live or non-replicating vaccines (similar to the COVID-19 vaccines) such as the flu jab and whooping cough vaccine, which have been used safely in pregnancy for years.

This review showed there are currently no fetal risks following gestational exposure to ‘non-live’ vaccines. It was therefore considered highly unlikely that COVID-19 vaccines would be harmful if administered in pregnancy.

RCOG and RCM supported this with their communications – stating the new COVID-19 vaccine would not be expected to have adverse effects on the developing fetus. However, at this stage, without reliable safety evidence for the COVID-19 vaccines specifically, we had to take a cautious approach.  At this point we advised that pregnant women who were at significant risk of developing severe COVID infections (those with medical co-morbidities or frontline health or social care workers)could choose to have the vaccine after discussing the benefits and risks with a healthcare professional.


Timeline of events

From the outset, it was always the opinion of the RCOG and RCM, supported by numerous expert organisations including UKOSS, MBRRACE-UK and UKTIS, that the benefits of vaccination in pregnancy would likely outweigh any risks.

The timeline demonstrates the numerous ways the RCOG, RCM and others promoted vaccination in pregnancy, drove research into safety and effectiveness, and improved risk-benefit communication.

Collectively, the RCOG and RCM vaccine subgroup worked closely with the Department of Health and Social Care, JCVI, UKHSA, NHS England and the devolved nations to ensure they had the latest evidence available on COVID-19 and pregnancy, encouraging the JCVI to offer the vaccine to all pregnant women and prioritise them for vaccination, once it was clear the benefits far outweighed any theoretical risks.

In April 2021, 100,000 pregnant women had been vaccinated in the US with no safety concerns raised and there was evidence available to show the vaccine didn’t cause adverse effects. The JCVI therefore announced pregnant women should be offered the vaccine along with other people in their age group.

When did the RCOG/RCM recommend the vaccine?

With the publication of each new dataset, the risk-benefit balance for COVID vaccination in pregnancy became better understood, and will continue to improve further in the future.

Safety data by themselves only relate to one side of the risk-benefit analysis. Throughout the pandemic, the RCOG, RCM and UKTIS have always recognised the non-static risk that the pregnant population in general faced from COVID-19.

For example, during lockdowns, pregnant women who were not high risk due to medical co-morbidities and could work from home, were likely at low risk of COVID-19. Yet, as rules eased, social distancing measures reduced and mask-wearing mandates discontinued, and with the arrival of more contagious variants, risks increased, particularly for the unvaccinated.

That is why in July 2021, as lockdown rules eased but the incidence rate increased, the RCOG and RCM strengthened their calls for all pregnant women to get vaccinated – updating their messaging from ‘strongly consider’ to ‘strongly recommend’. The American College of Obstetricians and Gynecologists updated their own advice to ‘recommend’ a few weeks later.

Where we are now

The arrival of new variants (Delta and Omicron) has posed different risks to pregnant women. Increasingly data has shown that COVID-19 in pregnancy has led to an increase in the risks of stillbirth, preterm birth and the mother requiring critical care.

In December 2021, after campaigning from RCOG and RCM, among others, and very clear data on the high risks of COVID-19 for unvaccinated pregnant women, the JCVI placed pregnant women in the ‘at-risk’ category recommending priority vaccination over and above people of the same age.

At the time of writing, studies investigating COVID-19 vaccine safety in pregnancy have included over 100,000 pregnant women, and 280,000 pregnant women in the UK and US have now received the vaccine.

There is no evidence that vaccination in pregnancy increases the risk of adverse pregnancy outcomes such as miscarriage, fetal anomalies, stillbirth, preterm delivery or impaired fetal growth.

The latest data from the UKHSA and Public Health Scotland has found more than 40% of women in the UK who gave birth in October 2021 had been vaccinated against COVID-19, although we think the figure now may be even higher. Our aim, of course, is for all pregnant women who don’t have a contra-indication – as well as anyone planning a pregnancy - to be vaccinated against COVID-19.

To reaffirm the message that the benefits of vaccination in pregnancy outweigh the risks, and the importance of being vaccinated in pregnancy, a national campaign from the Department for Health and Social Care was launched in January 2022, calling on all pregnant women to get either their first, second or booster dose as soon as possible.

While it has taken time for the message to evolve as the evidence accumulated – it is now clear. The benefits of COVID-19 vaccines in pregnancy vastly outweigh the risks and are strongly recommended, as they are the best way to protect women and their babies from the serious harm posed by COVID-19.

  • Clinical and research
  • Pregnancy and birth