About 1 in 10 women, who have COVID-19 during pregnancy, are likely to develop long-term COVID-19, according to a study.

While there is a growing body of research about the long-term effects of COVID-19 on the general adult population, little research has been done on the long-term impacts on those who get COVID-19 while pregnant.

Researchers from the University of Utah Health in Salt Lake City, US, followed a group of women from 46 US states plus Washington, DC, who got COVID while pregnant to see whether they developed long-term COVID-19, and if so, what factors put people at greater risk.

They found that 9.3 per cent of pregnant women developed long-term COVID-19 when evaluated six months or more after their initial infection. The most common symptoms people reported included feeling worn out after even minor physical or mental activity, also known as post-exertional malaise, fatigue, and dizziness.

The team also found that pregnant women who were obese or suffered from depression or chronic anxiety as well as those who reported having difficulty paying their bills were all at greater risk of developing long COVID. Those who had a more severe case of COVID-19 and required oxygen while pregnant were also at higher risk of developing long-term COVID-19.

"The key takeaway for clinicians who are taking care of pregnant patients is that nearly 1 in 10 people who have COVID during pregnancy still have persistent symptoms six months later," said lead author Torri D. Metz, a maternal-foetal medicine subspecialist and associate professor of obstetrics and gynaecology at the varsity.

"The trimester of infection was not associated with the development of long-term COVID-19, so it did not seem to matter when in their pregnancy people were infected."

The team also compared their findings to the larger cohort findings, which include non-pregnant women, and discovered that the rate of long-term COVID-19 appeared to be lower in pregnant women than in non-pregnant women.

"That could be due to several reasons that are worth investigating in the future," Metz said.

An important next step is to look at the outcomes of the infants of pregnant women who developed long-term COVID-19, the team said.

The findings will be presented at the ongoing Society for Maternal-Foetal Medicine's (SMFM) annual Pregnancy Meeting in the US.