Of the 1,140 pregnant women who presented at 15 hospitals in Maharashtra, 141 were found to be infected with novel coronavirus, translating to 12.3% prevalence. Pooled data of 141 pregnant women and 180 women from Nair Hospital in Mumbai revealed that only 11.5% of those infected showed symptoms, while the remaining 88.5% were asymptomatic.A small study of 1,140 pregnant women in Maharashtra found that 141 women were infected with novel coronavirus, translating to 12.3% prevalence of coronavirus infection among pregnant women. The study by researchers from the Mumbai-based ICMR-National Institute for Research in Reproductive Health (NIRRH) also found that nearly one in 10 pregnant women did not show any symptoms of coronavirus infection at the time of presentation in a hospital.
The prevalence of infection among pregnant women was based on data collected between April 25 and May 20 from 15 hospitals in the State where pregnant women presented at the time of labour or who were likely to deliver in the next five days. When the researchers pooled the data of 141 pregnant women with 180 women from Nair Hospital in Mumbai, which exclusively caters COVID-19 patients, they found that only 11.5% of pregnant women who were infected with the virus showed symptoms, while the remaining 88.5% were asymptomatic.
“Pregnant women generally have low immunity and are at increased risk of getting infected. It is therefore important to test pregnant women for coronavirus infection,” says Dr Deepak Modi from NIRRH and one of the authors of the study published in the European Journal of Obstetrics & Gynecology and Reproductive Biology. “Low immunity does not mean they would automatically show symptoms when infected.”
“Pregnancy is to some extent an immunocompromised state to protect the fetus. So yes, pregnant women are always at higher risk for infections, just like people on immunosuppression therapy (eg recovering cancer patients) and those with an immunodeficiency,” says virologist Dr Shahid Jameel, CEO of DBT-Wellcome Trust India Alliance says in email.
“The proportion of symptomatic to asymptomatic individuals varied greatly across the different cities. Our results estimate presence of one symptomatic to every nine asymptomatic pregnant women,” they write.
Can prevalence be extrapolated to community?
Can the prevalence of coronavirus infection among pregnant women be extrapolated to the general community? “No, I don’t think you can do that unless the sample size is very large. The other problem is that there are gender differences for infection and disease, and you would completely miss that out by looking only at women. For example, COVID-19 appears to have worse outcomes in men vs women. We don’t know whether men and women have different susceptibility to infection,” says Dr Jameel.
Dr Gautam Menon, Professor of Physics and Biology at Ashoka University, Sonepat, Haryana, says: “This is hard to [tell] without more information on the testing of close family members and on their locations. The prevalence in the general community is likely to be larger than that seen in the pregnant women in this study, but it is hard to estimate how much larger. The Mumbai serosurveys saw large differences between more and less affluent regions in the city, a difference that might be reflected in this data as well, if it could be analysed at a more granular level.”
Advantages of universal testing
The Indian Council of Medical Research (ICMR) had recommended universal testing for SARS-CoV-2 in pregnant women as infected women, including those who do not show symptoms, can infect the newborns and also pose a risk to health-care workers attending on them.
“This study has shown the importance of universal testing of pregnant women. Only this helped identify pregnant women who did not show symptoms,” says Dr Rahul Gajbhiye from NIRRH and a co-author of the paper. “Detecting asymptomatic pregnant women helped prevent the spread of the virus to newborns, health-care workers and others in the community.”