COVID-19 Severity in Pregnancy Appears Lower Than H1N1

Between March 1 and April 15, a total of 86,293 women gave birth. Only 427 of the births were to women with diagnosed COVID-19 that was serious enough for them to be hospitalized. The study does not include all women in the UK with SARS-CoV-2, as universal testing is unavailable, she said. Knight’s results only look at hospitalized women with confirmed SARS-CoV-2 infection and serious disease.

These are likely not all the women in the UK who gave birth while positive for SARS-CoV-2, said Knight, so the data still represent a small slice of the overall infection rate.

“What we can’t see is what potential impact a mild or indeed asymptomatic infection, if such a thing exists, has on the pregnancy,” Knight said. “I cannot from this study give you an infection rate. But I can give you a ‘hospitalized with infection’ rate.”

That rate is 4.9 per 1000 maternities. By comparison, the hospitalization rate — a marker of disease severity — of pregnant women with H1N1 was 8 per 1000 maternities.

This is notable and unexplained, said Christopher Zahn, MD, vice president of practice activities at the American College of Obstetricians and Gynecologists.

“It’s interesting because looking back at some of the other infectious outbreaks, such as H1N1, where pregnant women were at increased risk,” he told Medscape Medical News. “But with H1N1, pregnant women were at increased risk. But that’s not been identified in COVID either in international data or the emerging US data.”

Indeed, Lynne Mofenson, MD, senior HIV technical advisor to the Elizabeth Glaser Pediatric AIDS Foundation, saw Knight’s data, and has been tracking all the current studies on COVID-19 and pregnancy; she’s also been giving presentations on the current state of knowledge on the illness and pregnancy outcomes.

It’s a subject close to Mofenson’s heart. A former official at the Eunice Kennedy Shriver National Institute for Child Health and Human Development, Mofenson is best known for spearheading the government’s effort to prevent mother-to-child transmission of HIV in the late 1980s and early ’90s.

As of May 11, Mofenson found 100 papers — including Knight’s — describing the experiences of 1308 pregnant women with COVID-19 hospitalized worldwide. Only 44 (3.3%) those 1308 cases were single-case reports of extreme experiences. Fifty papers “appear to be duplicate reports on the same patients,” Mofenson wrote in a presentation she shared with Medscape Medical News.