Healthy pregnant women do not have an increased risk of severe Covid-19, a new study suggests.

At the beginning of the pandemic, pregnant women in Britain were included in the list of those deemed to be at moderate risk of the disease.

While there was no evidence that pregnant women were more likely to get seriously ill from coronavirus, they were added to the list of those deemed to be moderately clinically vulnerable as a precaution.

But a new observational study concludes that healthy pregnant women are at no higher risk of severe disease than women who are not pregnant.

However, like the general population, pregnant women who have some pre-existing conditions are at an increased risk of more severe Covid-19.

Those who have lung disease or diabetes are among those highlighted as being at increased risk, according to the study – which is yet to be peer-reviewed and has been published as a pre-print.

Researchers said that pregnant women with pre-existing conditions require “careful monitoring” if they become infected with the new coronavirus.

The team from Kings College London drew on data from people in Britain and Sweden participating in the Covid Symptom Study app and responses to the US-based Facebook Covid-19 Symptom Survey.

In the first group, the researchers analysed self-reported health data from around 14,000 pregnant women using the Covid Symptom Study app.

Among this group, 629 were deemed likely to have Covid-19 based on their symptoms and 21 were taken to hospital.

Scientists compared this with data from 387,000 non-pregnant female app users, where just over 25,000 were suspected to have the disease and nearly 600 ended up in hospital.

For the second group, the team looked at around 1.3 million survey responses from women, including nearly 42,000 from those who said they were pregnant. Just 2.9% of the pregnant respondents were suspected to have Covid-19, compared with 4% of the non-pregnant women.

Among those who did not require hospital care, the most frequent symptoms were loss of sense of taste and smell (anosmia) and headache.

For pregnant women who were taken to hospital, they frequently reported symptoms of a persistent cough and chest pain.

There was an increased incidence of gastrointestinal symptoms such as nausea and vomiting in the group of pregnant women who became most severely ill with Covid-19, which could be confused with similar symptoms that are due to the pregnancy itself, the researchers said.

Marc Modat, senior lecturer at King’s College London, said: “Our study highlights the power of gathering and analysing large-scale health data to understand how Covid-19 affects different groups within the population.

“We need to encourage as many people as possible to use simple health technology like the Covid Symptom Study app to shed light on this new disease and monitor its progress over the months ahead.”

Dr Erika Molteni from King’s College London added: “Although our findings should be reassuring for healthy women who are pregnant at this time, it highlights the importance of protecting those with underlying health conditions and keeping a close eye on them during their pregnancy, particularly if they start showing symptoms of Covid-19.

“It’s vital that we all keep taking steps to protect the health of everyone in our communities by sticking to social distancing guidelines, wearing face coverings in public and following good hand hygiene practices.”