Most pregnant patients not at high risk for COVID-19 complications, new study shows
November 24, 2020
It's tough to believe, but we are closing in on nearly a year of navigating the COVID-19 pandemic. More than 250,000 people in the U.S. have died of COVID-19-related causes in 2020 – more than seven times the estimated 34,200 U.S. lives lost to influenza in the 2018-2019 flu season.
Throughout the pandemic, the medical community has based recommendations for pregnant patients on what we know from past respiratory illness outbreaks – and the situation looked dire.
During the 2009 H1H1 flu outbreak, pregnant patients accounted for approximately 1% of infections but 5% of the total deaths, according to the Centers for Disease Control and Prevention (CDC). Preliminary CDC data suggested that COVID-19 would be no different, with potential for increased risks for ICU admission, mechanical ventilation, and preterm birth among patients diagnosed with the virus.
Up to now, most COVID-19 data related to pregnancy have come from hospitalized patients with severe illness. But a six-month study at UT Southwestern, published on the JAMA Network, is the first to examine outcomes of noninfected pregnant patients compared with those who had asymptomatic, mild, and severe cases of COVID-19.
Our study included 3,374 pregnant patients – 75% Latina, 18% black, and 4% white – who delivered at Parkland Health between March 18 and Aug. 22. Of these patients, 252 tested positive for COVID-19 at some point during their pregnancy and 3122 tested negative. (The higher frequency among Hispanic women in our study is consistent with data on racial and ethnic disparities in COVID-19 cases reported in the Dallas area and nationwide.)
Because we included mild and negative cases, our data are more reflective of community spread. We found that most pregnant patients who were diagnosed with COVID-19 did not experience severe symptoms and were never hospitalized, and they were not at increased risk for obstetric complications.
Now, as we approach winter, women who had COVID-19 early in pregnancy are preparing to deliver their babies. Data from their pregnancy outcomes will give us more information about how the virus affects an entire pregnancy through the baby's first days as a newborn. Using this information, we can further refine our recommendations to prevent and treat infection during pregnancy.
In that spirit, we want to take a moment to provide up-to-date information regarding COVID-19 and pregnancy – and what pregnant women should know as we enter the 2020 flu season.
1. Are pregnant women at increased risk for COVID-19 infection?
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.
2. Are all pregnant patients at high risk for severe complications?
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.
3. What is the risk to the fetus?
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.
4. What is my newborn's risk if I have COVID-19 at delivery?
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.
Pregnant in a Pandemic
For new and expectant moms, COVID-19 is encroaching on nearly every aspect of one of life’s biggest moments. Dr. Shivani Patel, a maternal-fetal medicine specialist, and one of her patients, Catandra Byrd, share firsthand the experiences of navigating a pandemic pregnancy – from prenatal care and baby showers to delivery day and postpartum worries.
Considerations for flu season
COVID-19 prevention methods – wearing a mask, washing your hands, and practicing social distancing – are similar to safety strategies for other respiratory illnesses, such as the flu and pneumonia.
Our doctors share valuable tips for navigating the potential perfect storm of dual respiratory viruses this winter.
Data show that communities that follow these strategies can greatly reduce the burden of illness. For example, the Southern Hemisphere has already gone through its 2020 flu season, which was much less severe than in previous years due to COVID-19 prevention strategies already in place.
Between Australia, Chile, and South Africa, there was a total of 51 positive influenza cases out of 83,307 tests – less than 1% positives – reported from April through July 2020. By comparison, there were 24,512 positive cases among 178,690 tests (nearly 14%) in these three countries during that same timeframe in 2019.
As the U.S. enters flu season, we recommend patients get vaccinated against influenza and continue to follow COVID-19 prevention strategies, even if cases begin to decline. By doing so, you can reduce your risk for catching either illness – or, in the worst-case scenario, suffering with both simultaneously.
Nearly a year into the pandemic, we are grateful that the situation for pregnant patients is less dire than first suspected. Nevertheless, all of us must continue to actively avoid spreading the virus and do everything we can to protect ourselves. Containing this pandemic is within our power, if we all commit to the strategies that work.
To visit with an Ob/Gyn about COVID-19 or the flu, call 214-645-8300 or request an appointment online.