Pregnant women should feel reassured by a UK study showing similar birth outcomes between those who have had a Covid-19 vaccine and those who have not, a researcher has said.

There were no statistically significant differences in the data, with no increase in stillbirths or premature births, no abnormalities with development and no evidence of babies being smaller or bigger, a paper from a team at St George’s, University of London said.

Thousands of pregnant women in England have been vaccinated against coronavirus, with no safety concerns reported.

But the latest data – which researchers said is the first from the UK focusing on safety outcomes for pregnant women – should add an extra layer of reassurance for expectant mothers, said lead author Professor Asma Khalil.

Separate research last month revealed the vast majority of pregnant women admitted to hospital with Covid-19 are unvaccinated and there has been a drive in recent weeks to encourage more to get a jab, with England’s chief midwife writing to GPs and fellow midwives to spread the message.

The latest study considered 1,328 pregnant women – of whom 141 received at least one dose of vaccine before giving birth and 1,187 women who did not.

All the women gave birth at St George’s University Hospitals NHS Foundation Trust in London between March 1 and July 4 this year.

The paper, which has been peer-reviewed and published in the American Journal of Obstetrics and Gynecology, states: “This study contributes to the body of evidence that having Covid-19 vaccination in pregnancy does not alter perinatal outcomes.”

Researchers compared those who had a vaccine to a propensity score-matched cohort of pregnant women who did not receive a jab, taking account of factors such as deprivation, ethnicity and co-morbidities.

They found that there was evidence of reduced vaccine uptake in younger women, those with high levels of deprivation, and women of Afro-Caribbean or Asian ethnicity, compared to Caucasian ethnicity.

Of the pregnant women eligible for a vaccine, less than one third accepted a jab during pregnancy, the researchers said.

Prof Khalil, a professor of obstetrics and maternal fetal medicine, said pregnant women should take comfort from this latest data.

She told the PA news agency: “This is data from the UK, from women who have given birth between March and July and we compared them with women who were pregnant at the same time during the pandemic, exposed to the same changes that we all have been exposed to during the pandemic and we looked at the outcomes in full detail and reviewed all the records in detail, and this is the data and there was no difference.”

She said they were “really pleased” with the data when it comes to safety, but added that it is “worrying” in terms of the low vaccine uptake among pregnant women.

Prof Khalil said in her experience in speaking to pregnant women, she believes there has been a change in uptake in recent weeks with “a significant proportion of pregnant women” saying they have now received a jab.

Dr Edward Morris, president at the Royal College of Obstetricians and Gynaecologists (RCOG), said: “This is the first data from the UK showing the safety outcomes in pregnancy after having the Covid-19 vaccine.

“The data shows that pregnant women who had received the Covid-19 vaccine were not at an increased risk of stillbirth, nor their babies more likely to have fetal abnormalities or be small at gestational age, compared to women who had not had the vaccine.

“With emerging data like this, we hope pregnant women feel reassured that the vaccine is safe in pregnancy and it is the best way to protect women and their babies from the known harms of Covid-19 in pregnancy, including severe illness and premature birth.

“We are seeing higher numbers of pregnant women in hospital with severe symptoms of Covid-19 and urge pregnant women take up the offer of a vaccine.”

Earlier this month a new study was launched to determine what the best gap is between coronavirus vaccine doses for pregnant women.

Researchers are aiming to recruit more than 600 pregnant women for the trial, which will monitor the vaccine’s effectiveness and follow the development of children up to one year old.

Those involved, including Prof Khalil, said they hope the findings will reassure expectant mothers further on the safety of Covid-19 jabs.