New data from the University of Oxford shows a rise in hospital admissions for unvaccinated pregnant women, leading experts to encourage mothers-to-be to have the Covid jab.
We take a look at the latest situation.
Since the start of the pandemic, the UK Obstetric Surveillance System (UKOSS) has been gathering information on all pregnant women who've been admitted to hospital in the UK with symptoms of confirmed Covid-19.
The latest UKOSS data shows there's been a worrying rise in unvaccinated pregnant women being admitted to hospital with severe Covid-19, amounting to 200 in the past week.
The statistics, published by the University of Oxford on the MedRXiv site, reveal that out of these 3,371 women admitted to hospital with symptomatic Covid:
The research also shows that Covid-19 vaccines offer effective protection from these risks - 55,000 pregnant women in the UK have had one or both doses of the vaccine, and as only 1% of pregnant women hospitalised by Covid-19 were vaccinated this shows that vaccination isthe most effective way of protecting women and their babies against the effects of Covid-19.
As a result, Jacqueline Dunkley-Bent, the chief midwifery officer for England, has written to GPs and fellow midwives across the country to stress how important it is for pregnant women or those considering pregnancy to get vaccinated as soon as possible.
She says: 'Vaccines save lives, and this is another stark reminder that the Covid-19 jab can keep you, your baby and your loved ones safe and out of hospital.'
Up until now, simply being pregnant wasn't seen as a reason to be given the vaccine.
In line with the rest of the population, pregnant women were advised to have the vaccine based on their age and clinical risk group. However, this latest rise in hospital admissions among pregnant women, caused by the Delta variant, has altered this strategy.
Gill Walton, chief executive of the Royal College of Midwives, says: 'It's so important for pregnant women to get their jab, particularly with the virus being so prevalent and the Delta variant proving itself to be so much more transmissible.'
In fact, the UKOSS data suggests that pregnant women with Covid-19 are getting it more severely now than with the first wave - 45% of pregnant women admitted to hospital with the Delta variant experienced moderate or severe disease, compared with 36% with the Alpha variant and 24% with the first wave.
Women who are unsure about having the jab are being reassured that any potential side effects - such as a localised swelling at the injection site - are far outweighed by the clinically recognised benefits of being jabbed. For example, as well as protecting the mother, studies have shown that women who have received the vaccine pass on antibodies to their babies.
Experts are united in their view that pregnant women should be vaccinated as soon as possible.
Marian Knight, professor of maternal and child population health at the Nuffield Department of Population Health, University of Oxford, and chief investigator of the study, says: 'Around 200 pregnant women were admitted to hospital with Covid-19 last week. I cannot emphasise more strongly how important it is for pregnant women to get vaccinated in order to protect both them and their baby.'
Nicola Vousden, registrar in public health and the first author of the study, says: 'This study shows that very few pregnant women are admitted to hospital with Covid-19 after they have received a vaccine.'
Dr Edward Morris, president of the Royal College of Obstetricians and Gynaecologists, says: 'Every day our members are seeing very sick pregnant women with Covid-19 in hospital, and the majority are unvaccinated.
'We want to reassure pregnant women that Covid-19 vaccines are the safest and best way to protect you and your baby from severe illness and premature birth.'
Professor Knight says: 'Until they are vaccinated, pregnant women must continue to be extremely attentive to social distancing measures including mask wearing, 2-metre distancing and meeting outdoors where possible.'
Whether you're already pregnant or considering pregnancy, get your first jab - and book your second one as soon as you're able to. You can have your second dose eight weeks after your first.
Gill Walton says: 'Getting the vaccine is the best way to protect you and your baby against Covid-19. It really is that simple. Hundreds of thousands of pregnant women worldwide have been vaccinated, safely and effectively protecting themselves against Covid and dramatically reducing their risk of serious illness or harm to their baby.'
'If you have questions, talk to your midwife, talk to your obstetrician, talk to your GP,' says Gill Walton. 'Get the answers you need and get the jab.'
The Joint Committee on Vaccination and Immunisation (JCVI), which advises the government on vaccinations, says it's preferable for pregnant women in the UK to be offered the Pfizer-BioNTech or Moderna mRNA vaccines, where available.
This is because the data from these vaccines hasn't raised any safety concerns.
Some women may have had their first dose of the AstraZeneca vaccine prior to or earlier on in their pregnancy and are wondering what to do now that their second dose is due.
There have been very rare reports of serious blood clots after a second dose of the AstraZeneca vaccine in some people (not specifically pregnant women) so the Green book - the official national publication on vaccines - advised on 7 May 2021 that Pfizer and Moderna vaccines are the preferred vaccines for eligible pregnant women of any age.
Although there are no reported concerns with the AstraZeneca vaccine in pregnancy, there is more extensive experience of the Prifzer and Moderna vaccines being given to pregnant women, hence the JCVI recommending the Pfizer-BioNTech or Moderna mRNA vaccines, where available.
If you have had the first dose of AstraZeneca, you can choose whether to have the second dose in pregnancy or to defer until afterwards but the advice is to complete the same vaccine because the second dose will be important for longer lasting protection against Covid-19.
The safety of mixing different vaccines is being investigated in an ongoing trial (the ComCov trial), although it doesn't include pregnant women. The RCOG says: 'Initial data from the study, published on 12 May 2021, showed that mixing vaccines appears to be safe overall.'
However, there was an increase in short-lasting effects such as fever for individuals who were given two different vaccines compared to individuals who had two doses of the same vaccine.
Further information from this trial is expected later this year.
The RCOG is aware that there are concerns about the second vaccine, particularly given the conflicting information that was given in the early stages of the vaccine roll out.
It says it has been working closely with various organisations including the RCM, NHS England and Public Health England to provide accurate information on vaccines. It has also been in regular contact with the JCVI to ask them to give consideration to pregnant women when making their decisions.
This month it's been announced that UK researchers from St George's, University of London have launched a clinical trial called Preg-CoV that will explore the optimal vaccination schedule for pregnant women, and help to allay any concerns about getting the jab.
The trial experts hope to recruit 600 pregnant women aged between 18 and 44 from 13 sites across England.
Randomised groups of pregnant women will receive either the Pfizer or Moderna vaccines at different points in their pregnancy, with their second doses also at different points.
Researchers aim to fill in any gaps in knowledge about the vaccine, including potential side effects and also the benefits of the jab for babies - the team will track outcomes for the babies up to 12 months after birth.