Women who have Covid-19 towards the end of their pregnancy are vulnerable to birth-related complications. They are more likely to have complications than those who get Covid-19 in the earlier stages of pregnancy or who haven’t had Covid-19 at all, according to research published in Frontiers in Immunology.

The findings show that preterm births, stillbirths and newborn deaths are more common among women who have the virus 28 days, or less, before their delivery date. The majority of complications, which also include Covid-related critical care admissions, occurred in unvaccinated women, according to one of the first national studies of pregnancy and Covid-19.

Researchers say more should be done to increase vaccine uptake in pregnant women, whose vaccination rates are much lower than those of women in the general population.

The team analyzed data relating to all pregnant women in Scotland. It included more than 87,000 women who were pregnant between the start of vaccination uptake in December 2020 and October 2021.

Vaccination uptake during the study period was lower in pregnant women, compared with women aged 18 to 44 in the general population.

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

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

Some 12% of Covid-19 cases were in partially vaccinated pregnant women – those who had only received one vaccine dose, or were diagnosed less than 14 days since their second dose. This compares with 11% of cases in fully vaccinated women.

The team analyzed data on extended perinatal deaths, which is defined as 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.

All baby deaths occurred to women who were unvaccinated against Covid-19 at the time of infection.

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.

These data were then compared to the background rates of extended perinatal deaths and preterm births, which are the rates for all babies born in Scotland regardless of whether their mother had previously had Covid-19 or been vaccinated.

The background perinatal mortality rate during the pandemic in Scotland was six per 1,000 and preterm birth rate was 8%.