By Jay Furst

The COVID-19 pandemic has added a new and hard-to-answer concern for pregnant women: Does COVID-19 pose greater risks for the mother during pregnancy?

Kavita Narang, M.D., a fellow in the Mayo Clinic Division of Maternal and Fetal Medicine, recently co-authored a review in Mayo Clinic Proceedings on COVID-19 and pregnancy. The review of research to date concludes that pregnant women may be at greater risk for COVID-19 infection.

"The severity of the disease is highly variable, and pregnant women with underlying comorbidities or medical health conditions are at higher risk of worse outcomes," says Dr. Narang.

According to Dr. Narang, most of the knowledge on respiratory viral infections that occur during pregnancy comes from data on influenza, SARS and MERS pandemics. Pregnancy could represent a vulnerable condition that increases the risk of infection and complications such as preterm delivery. This has been true in past pandemics, and Mayo Clinic researchers are exploring how the SARS-CoV-2 virus may or may not be different.

Early and late stages of pregnancy pose greater risk

The physiological changes that occur during a normal pregnancy open the door to impacts from the virus. The virus enters cells via the angiotensin-converting enzyme 2 (ACE2) receptor, which is upregulated during normal pregnancy. As a result of higher ACE2 expression, pregnant women may be at elevated risk for complications. The cascade of events that occur once the virus binds to the ACE2 receptor is similar to what occurs with preeclampsia, a potentially serious complication during pregnancy that can lead to high blood pressure and possible damage to other organs.

In fact, several overlapping cellular mechanisms can be affected by the viral infection, all potentially resulting in progressive vascular damage. Tissue injury also can occur due to excessive inflammatory and immune responses during pregnancy. Though data on immune responses to SARS-CoV-2 in pregnant women are limited, research from previous pandemics suggests that pregnancy may increase the risk of becoming infected, and the timing of infection during gestation may result in differences in the mother's immune responses, viral clearance and outcomes.

Because women’s bodies naturally promote inflammation during first and third trimesters to encourage implantation and labor, women infected with respiratory viruses, particularly SARS-CoV-2, early or late in pregnancy may be at higher risk of exaggerated immune responses to the virus.

”During pregnancy, a woman’s immune system must adapt to support the growth and development of her baby,” says Elizabeth Enninga, Ph.D., a study co-author and clinical researcher in Mayo Clinic's Department of Obstetrics and Gynecology. ”This adaption tightly controls responses that would harm the baby while also protecting the mother from viruses and/or bacteria.”

Knowledge regarding the care, treatment and preventative strategies of pregnant women during the era of the SARS-CoV-2 pandemic is rapidly evolving. Data are limited and preliminary and likely to change once larger data sets become available.

“If you are pregnant and you have concerns about virus exposure or symptoms, it’s important to consult your obstetrician so you can work together to ensure you are receiving the most up-to-date care,” says Dr. Narang.

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Learn more:

• Read Pregnancy and COVID-19: What are the risks?
• Listen to the Mayo Clinic Q&A Podcast: Pregnancy during the COVID-19 pandemic
• Read Women’s Wellness: Is it safe to get a flu vaccination during pregnancy

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Tags: COVID-19, Elizabeth Enninga, Findings, gynecology, Kavita Narang, Mayo Clinic Proceedings, News, obstetrics, preeclampsia, pregnancy, women's health