Health leaders are urging pregnant women to get a Covid-19 vaccine after figures suggested only around one in 10 may have had a first dose.
The data, from Public Health England (PHE), shows for the first time that 51,724 women in England who were pregnant or thought they could be have received at least one dose of a jab since mid-April.
The figure is likely to be at least 4,000 higher when taking into account the numbers who have already had a vaccine because they are clinically vulnerable or because they are a health or social care worker.
Nevertheless, leaders say they want more women to come forward, with 95% of pregnant women in hospital last week with Covid-19 being unvaccinated.
In the 2020/21 flu season, 606,540 women were registered as pregnant with their GP, suggesting only around one in 10 may have had a first dose across England.
However, determining an accurate number of eligible women is difficult due to how pregnancy is recorded and the number of women entering and leaving the group due to giving birth, miscarriage or abortion.
Of the total number vaccinated after mid-April, just 20,648 women have received their second dose.
Pregnant women who do get symptomatic Covid-19 are two to three times more likely to give birth to their baby prematurely.
Though uncommon, severe illness due to Covid-19 is more likely in later pregnancy.
Dr Edward Morris, president of the Royal College of Obstetricians and Gynaecologists, welcomed the figures but said he hoped more women would take up the vaccine.
He said: “We are encouraged to see more than 50,000 pregnant women in England have received one dose of a Covid-19 vaccine.
“We recommend vaccination in pregnancy as it’s the most effective way of protecting women and their babies from severe illness and premature birth.
“We are concerned that increasing rates of Covid-19 infection will adversely impact pregnant women.
“Of the pregnant women in hospital with Covid-19 last week, 95% were unvaccinated.”
“While uncommon, severe illness from Covid-19 is more likely in later pregnancy, and infection increases the risk of a premature birth.
“The Covid-19 vaccines are one of the best defences against infection, preventing at least 11.7 million infections in England alone.”
Dr Mary Ramsay, head of immunisation at PHE, said: “It is encouraging that thousands of pregnant women have received a Covid-19 vaccine.
“We strongly urge anyone who has not yet taken up the offer to get both doses as soon as possible and for pregnant women to come forward for their second dose eight weeks after their first dose.
“The vaccines continue to save thousands of lives and we are confident that they can be safely offered to pregnant women, but if you have any questions or concerns please don’t hesitate to discuss these with a healthcare professional.”
Gill Walton, chief executive of the Royal College of Midwives, said: “It’s really encouraging that so many pregnant women have already come forward to the vaccine – particularly bearing in mind this figure doesn’t include the pregnant health and care workers or those who are clinically extremely vulnerable, who would have received at least their first vaccine before April 16.
“We’re all very aware of just how widely the virus is still circulating.
“That’s why it’s so important for pregnant women to take up the vaccine.
“We are seeing increasing numbers of pregnant women being admitted to hospital with serious illness, almost all of whom are unvaccinated.
“Pregnant women are at greater risk of serious illness if they get Covid, and those with severe Covid are twice as likely to experience a stillbirth and three times as likely to have a preterm baby. Getting the vaccine is the best way to keep you and your baby safe.”