Coronavirus: COVID-19 believed to have caused woman's miscarriage

Worryingly, the virus appears to have breached the placental barrier. Photo credit: Getty

Boris Johnson's partner Carrie Symonds gave birth to a healthy boy last week, despite spending part of her pregnancy bedridden with a likely COVID-19 infection.

While her experience and other studies have found there's no increased risk of death for pregnant women compared to others, COVID-19 is now suspected to be the cause of a miscarriage in Switzerland.

Worryingly, the virus appears to have breached the placental barrier.

The 28-year-old, pregnant for the first time, showed up at Lausanne University Hospital on March 20 with fever, dry cough and fatigue - all symptoms of COVID-19, which has killed hundreds of thousands of people worldwide since emerging from China at the start of the year.

She miscarried two days later. Testing of the placenta showed it had been infected with SARS-CoV-2, the virus behind COVID-19. 

"This case of miscarriage during the second trimester of pregnancy in a woman with COVID-19 appears related to placental infection with SARS-CoV-2, supported by virological findings in the placenta," the doctors said in a case study, published online by the journal JAMA.

"No other cause of fetal demise was identified."

The woman was obese, known to increase the risk of death in COVID-19 patients.

The researchers say more research is needed into whether the virus could be a risk to unborn babies, or if it's an isolated case.

Unlike most other viral diseases with high mortality rates, COVID-19 rarely kills young children.

Few viruses are known to be capable of crossing the placental barrier - among them are rubella, chickenpox, HIV and zika.