Most pregnant patients not at high risk for COVID-19 complications, new study shows

There is no evidence that pregnant women are more susceptible to COVID-19 infection than non-pregnant women in their same age range. Pregnant women face the same risks of infection from gatherings and group settings as nonpregnant women and should use masks, social distancing, and other recommended measures to prevent transmission. However, people often confuse risk of acquiring infection with risk of experiencing severe symptoms.

We know that pregnant women generally have more severe symptoms for other respiratory illnesses, such as influenza. In the third trimester, a pregnant woman's lung capacity decreases 20% to 30% and her oxygen consumption increases by 20%. So, pregnant patients with respiratory infections potentially need more breathing support or supplemental oxygen than their nonpregnant peers, which brings us to our next question.

Probably not – at least not as high risk as was thought at the beginning of the pandemic. UT Southwestern's data showed that 95% of pregnant patients had asymptomatic or mild illness, while 5% develop severe or critical illness from COVID-19.

The overall risk of hospitalization among pregnant patients diagnosed with COVID-19 was similar to that reported in nonpregnant patients, at approximately 5%. Unfortunately, when a virus affects millions of people, that still accounts for a high proportion of individuals who might need intensive care, ventilators, and experience long hospital stays.

Throughout the pandemic, CDC data have been alarming for patients and physicians. In June, CDC's Morbidity and Mortality Weekly Report showed much higher rates of hospitalization and nearly double the rate of ICU admission among pregnant patients with COVID-19.

In November, the CDC reported that the risk of preterm birth was 12.9% overall compared to approximately 10.2% for the general population and the risks of ICU admission, mechanical ventilation, and death among pregnant patients with COVID-19 were approximately three times higher (1 in 100 pregnant patients vs. 1 in 333 nonpregnant patients).

The marked differences in reporting are likely due to which patients' outcomes were tracked. The CDC acknowledges that much of its data are missing from the preliminary reports and may be skewed toward more severe cases. The absolute risk for complications is still relatively low.

UT Southwestern's data reflect patients diagnosed with COVID-19 prior to and at various stages of pregnancy, giving us a deeper pool of information about symptom severity, illness progression, and outcomes from the start of the pandemic to date.

Keep in mind that, just as in the general population, having underlying medical conditions may place you at higher risk of complications. Our data show that pre-existing and gestational diabetes are associated with increased severity of maternal illness. And you are more likely to experience COVID-19 complications if you were obese prior to pregnancy or had other high-risk conditions such as high blood pressure, an immunocompromising disease, or asthma.

So far, we have not seen an increase in babies born with congenital malformations associated with this virus like we see with rubella or Zika virus.

We know COVID-19 is a respiratory virus, which means it is transmitted through droplets from breathing, coughing, sneezing, and speaking. To get to the placenta, the virus would have to enter the mother's bloodstream and breach the placenta, which is possible but unlikely.

Very few cases of vertical transmission – in utero infection – have been reported. At UT Southwestern, we have seen one case in which there were COVID-19 viral particles in the placental membrane. Though there is some evidence vertical transmission can occur, it appears to be rare with risk factors that are not yet known. Horizontal infection (after delivery) is more plausible, but still relatively low at approximately 3%.

Our study showed no increased risk for preterm birth among pregnant patients with COVID-19 compared to patients who did not have COVID-19. However, among the few patients who developed severe or critical illness from COVID-19, the risk of preterm birth was higher. Because underlying medical conditions such as diabetes may place you at risk for developing severe or critical COVID-19 infection, prevention strategies are key to protecting both you and your baby.

Before we knew that the risk of newborn infection was low, the American College of Obstetricians and Gynecologists (ACOG), as well as hospitals around the U.S., recommended isolating newborns from mothers who were known to be infected with COVID-19.

Now that we know most newborns who get COVID-19 exhibit mild or no symptoms and have good outcomes, we no longer recommend isolating the baby from the mother after delivery if the mother is infected but does not have active symptoms – unless there is a clinical reason to do so, such as fever or respiratory distress. If the baby stays in the mother's room, the mother must wash her hands frequently and wear a face covering at all times when near her baby.

We also provide an in-room isolette, a clear, enclosed crib, which helps reduce a newborn's exposure to germs. Keeping babies with their mothers when it’s safe increases opportunities for bonding and breastfeeding. We also do not routinely test newborns whose mothers recovered from COVID-19 over a month before delivery unless the baby shows symptoms.

If a mother is infected and has active respiratory symptoms, we will likely recommend the baby stay separate from the mother to promote healing and reduce the risk of infection to the newborn or other family members.