The COVID-19 pandemic continues to change our everyday lives while we await the progress of new treatments and vaccines to combat the risks of the illness. People who are pregnant and nursing are more susceptible to severe infections from respiratory viruses, such as the flu. This susceptibility may also put pregnant people at a greater risk for severe COVID-19 infection, but how it affects fetal development was a major unknown as the SARS-CoV-2 virus began to spread in early 2020. Although there are limited data, studies are beginning to shed light on the pregnancy-related risk of severe COVID-19.

We frequently hear about the “cytokine storm,” an overreaction of the immune system that is a significant risk factor for more serious progression of COVID-19. Pregnancy, especially the later stages, causes changes to the immune system. A healthy pregnancy produces more of two types of “helper” immune cells. The shift in the ratio between these two types of cells could lead to an increased risk of becoming infected with the coronavirus because the virus may be more likely to grow in this altered immune system. However, studies suggest that pregnant people may not be more susceptible to COVID-19 infection, but that COVID-19 severity may be worse in pregnant people.

A recent study found that pregnant women hospitalized for COVID-19 had a higher rate of preterm delivery and stillbirth than those without COVID-19. In addition, the study found a significant correlation between people who had gestational diabetes and pre-pregnancy obesity and more severe COVID-19 symptoms and the need for mechanical ventilation. Immune system dysfunction is common in gestational diabetes and obesity in pregnancy. This study helped form the basis for the American College of Obstetricians and Gynecologists’ recommendation that people who are pregnant—especially those with metabolic syndrome—need to take particular care to avoid coronavirus exposure.

Whether or not a fetus can become infected with the coronavirus remains a question. A recent review published in Physiological Reviews found that the coronavirus has been detected in the placenta, amniotic fluid and umbilical circulation in rare situations, however another recent paper found that no infants born to parents with COVID-19 tested positive for the virus 24 hours after birth. No cases of fetal COVID-19 infection in other reports have been found so far. However, more research with larger clinical sample sizes is needed. While current data may indicate that infection can’t cross the placenta, scientists don’t know yet what the lasting effects are on a baby whose parent had COVID-19 during pregnancy.

Until we know more about COVID-19 and pregnancy, guidelines recommend taking precautions to avoid exposure: wear masks, practice physical distancing, get a flu shot and avoid potentially infectious situations. Although in-person doctor’s visits may be suspended for some, virtual monitoring of prenatal care—particularly of those with high-risk pregnancies due to metabolic disorders—should continue.