SALT LAKE CITY — Pregnant women who developed severe symptoms of COVID-19 were at higher risk of pregnancy complications and even death compared to women who experienced no symptoms, or mild or moderate symptoms, according to a new study led by a University of Utah researcher.
The good news, according to the study, is that most pregnant women who were studied didn't experience severe or critical effects of COVID-19; however, Dr. Torri Metz, an associate professor and maternal-fetal medicine subspecialist at University of Utah Health, and the study's lead author, said it's still difficult to know why some pregnant women developed severe symptoms while others didn't.
"(Adverse effects) do seem to be predominately limited to that severe and critical group but we don't have control over who ends up being in that severe and critical group," she said, in a briefing with media Friday. "And since that was 12% of our population, I think we have to take that into context to know that if pregnant women do develop COVID-19, they are at risk for developing severe and critical illness. And if they do, they are at risk for adverse pregnancy outcomes."
The study was released Friday in time to be presented at the Society for Maternal-Fetal Medicine's annual meeting. Researchers analyzed data from more than 1,200 pregnant women at 33 hospitals across 14 states from March 1 through July 31, 2020.
In all, nearly half were asymptomatic, while 27% reported mild symptoms and 14% experienced moderate symptoms. Another 8% experienced severe symptoms and 4% experienced critical symptoms.
Who is most at risk?
The new study builds off recent findings from the Centers for Disease Control and Prevention, which found that pregnant women were at higher risk for death or complications than nonpregnant women who contracted the virus. Metz said that her study's findings could be viewed as reassuring for women who experience mild or moderate COVID-19 symptoms, which was the majority of those who experienced any symptoms of the coronavirus.
That said, the difficulty in knowing why some women ended up asymptomatic while others were hospitalized make it difficult to project what will happen when someone gets the virus. The research pinpointed some factors that were higher in severe and critical cases compared to the other groups.
Those who tended to experience worse symptoms were older, had higher body mass index, and were more likely to have underlying health conditions like asthma, diabetes or high blood pressure, researchers discovered. The women more likely to suffer severe outcomes from the coronavirus were more likely to die or have serious complications like preterm birth, postpartum hemorrhage or heavy bleeding after childbirth, high blood pressure during pregnancy, or have a cesarean delivery.
The death rate from the study of COVID-19 in women was also 0.3%, which would equate to 3 deaths per 1,000 or 300 per 100,000. The last known rate of 17.4 deaths per 100,000 in pregnant women without COVID-19, according to the CDC.
"This is much higher than would be expected at baseline and it's certainly concerning," Metz said. "In pregnancy, we're seeing the same thing that we're seeing in nonpregnant people in that there are increased death rates over this time period."
The data on higher deaths tied to COVID-19 is something that Metz's University of Utah Health colleagues mentioned during a briefing Thursday. During that briefing, experts said COVID-19 was the third-leading cause of death in Utah during 2020 behind heart disease and cancer. It even outpaced heart disease and cancer at points during the end of the year.
While the study found the rate of minority women contracting COVID-19 was disproportionate to population data, the study didn't find a difference in disease severity by race. Those results mirrored other studies that showed minority communities adversely affected by COVID-19 infection but no known biological difference that would result in a worse reaction to the coronavirus.
The researchers were "in some ways" surprised by the findings. Metz explained that they weren't sure if there were adverse pregnancy outcomes with COVID-19 when they began the study. They also didn't know if those would be influenced by the severity of the disease.
There were some limitations to the study as well. She added a "vast majority" of the patients studied were in the third trimester of their pregnancy. Researchers still don't know if infection in the first trimester would cause birth defects.
What to consider before pregnancy
There is no formal advice for pregnancy during the pandemic. Knowing the risks of COVID-19 illness is something women have to weigh in the decision over having a child during the pandemic, Metz said.
Women who have high blood pressure, diabetes, or are obese already have at higher risk for complications, she said. Adding the high risk for severe COVID-19 outcomes just adds on top of those risks.
"We do want these patients to weigh all of these things when they're considering pregnancy, when they're considering the COVID-19 vaccine in pregnancy, but I don't think there's a one size fits all answer for that question."
Since there is no way of knowing someone's outcome in advance, she advised that pregnant women wear a mask, practice social distancing and follow all other public health measures aimed at reducing the risk of contracting COVID-19.
Advice for COVID-19 vaccination during pregnancy
Pregnant women weren't included during the initial COVID-19 vaccine trials. Pfizer is currently in the process of studying the vaccine in pregnant women but those trials aren't yet completed. At this point in the vaccine rollout, pregnant medical professionals, emergency response or teachers would be among the individuals who would have to make the decision about vaccination.
The CDC's official stance on the matter is that those who are pregnant should consult their health care provider since there are no data on the subject. It added there are no indications of risk from mRNA vaccine studies.
"When making a decision, pregnant people and their health care providers should consider the level of COVID-19 community transmission, the patient's personal risk of contracting COVID-19, the risks of COVID-19 to the patient and potential risks to the fetus, the efficacy of the vaccine, the side effects of the vaccine, and the lack of data about the vaccine during pregnancy," the CDC advises.
While the study didn't address vaccines, Metz said that study allows medical experts to better pinpoint the risks of not getting vaccinated during pregnancy. She added that it would have been much easier to weigh all of the benefits and risks of the virus or vaccine had pregnant women been included in the initial vaccine trials. She expected those who are most at risk for severe outcomes and thus pregnancy complications would be most likely to want the vaccine.
"Ultimately, this is a choice that needs to be offered to pregnant people," she said, "and I'm so glad it's available in the United States for women."