Women who have Covid-19 towards the end of their pregnancy are more vulnerable to stillbirths, newborn deaths and birth related complications, a new study suggests.

The research also found that most complications occurred in women who were not vaccinated, with the majority (98%) of pregnant women with Covid-19 who were admitted to critical care being unvaccinated.

The study, which included more than 87,000 women in Scotland found that preterm births, stillbirths and newborn deaths were more common among women who had the virus 28 days or less before their delivery date, compared to background rates.

All the women whose babies died had not been vaccinated against Covid-19 at the time of infection, though experts stressed that it is not possible to say if Covid-19 contributed directly to the deaths or preterm births as they did not have access to detailed clinical records for individual women.

Researchers found that vaccination uptake during the study period, between December 2020 and October 2021, was lower in pregnant women, compared with women aged 18 to 44 in the general population.

Just under a third (32%) of pregnant women who gave birth in October 2021 were fully vaccinated – meaning more than 14 days had elapsed since a second vaccine – compared with 77% of the general female population aged 18 to 44.

Experts said the findings, which are part of the the Covid-19 in Pregnancy in Scotland (Cops) study, highlight the importance of getting the vaccine.

Cops co-lead Dr Sarah Stock, of the University of Edinburgh’s Usher Institute , who is also a consultant obstetrician, said: “Our data add 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 Covid-19.”

The team analysed data on extended perinatal deaths, which is defined as the death of a baby in the womb after 24 weeks of pregnancy, or in the first 28 days after birth.

They found that the extended perinatal death rate among babies born within 28 days of their mother developing Covid-19 was 23 per 1,000 births.

This was then compared to the background perinatal mortality rate, the rate for all babies born in Scotland regardless of whether their mother had previously had Covid-19 or been vaccinated, which was six per 1000 births during the pandemic.

Some 17% of babies born within 28 days of their mother developing Covid-19 were delivered prematurely – more than three weeks before their due date – compared to a background preterm birth rate of 8%.

The study said that, to date, there has been one maternal death following Covid-19 infection in pregnancy in Scotland.

Since the start of Scotland’s vaccination programme, a total of 4,950 cases of Covid-19 have been confirmed during pregnancy, with 77% of these cases in unvaccinated women.

The team monitored complication rates in women who received a Covid-19 vaccination during pregnancy and found that the perinatal mortality and preterm birth rates in women within 28 days of receiving a vaccine were very similar to background rates, which experts said provides further reassurance on the safety of vaccination during pregnancy.

The Joint Committee on Vaccination and Immunisation (JCVI), in December, said that pregnant women should be regarded as a clinical risk group for Covid-19 and should be given vaccines quickly.

Cops co-lead, Dr Rachael Wood, Consultant in Public Health Medicine with Public Health Scotland, said: “It is clear that vaccination is the safest and most effective way for pregnant women to protect themselves and their babies from severe Covid-19 disease.”

The research team included scientists from the Universities of Edinburgh, Glasgow, Aberdeen, Strathclyde, and St Andrew’s, Public Health Scotland, and Victoria University of Wellington.

The findings have been published in Nature Medicine.