Pregnant COVID-19 Patients Have Low In-Hospital Mortality Rates

By Lisa Rapaport

May 11, 2021

(Reuters Health) - Women hospitalized with COVID-19 appear to have lower mortality rates when they're pregnant than those who are not pregnant, even when they're admitted to intensive care, a U.S. study suggests.

Researchers examined data on 1,062 pregnant and 9,815 non-pregnant U.S. women hospitalized with COVID-19 and viral pneumonia from April to November 2020. Overall, in-hospital deaths were less common among pregnant patients (0.8%) than among non-pregnant patients (3.5%).

Even in the high-risk subset of patients admitted to intensive care units, in-hospital mortality was still lower among pregnant patients (3.5%) than among non-pregnant patients (14.9%), the study team reports in the Annals of Internal Medicine.

"The result is surprising in that most of the other studies including ones done by the CDC showed an increased risk of mortality among pregnant women with COVID-19," said senior study author Dr. Anthony Harris, an associate hospital epidemiologist at the University of Maryland Medical System in Baltimore.

"But the other studies that found an increased risk suffered from a reporting bias which likely led to a higher proportion of pregnant women with bad outcomes being reported to the voluntary reporting system and pregnant women who did well not being reported," Dr. Harris said by email.

While COVID-19 remains dangerous to all patients, regardless of pregnancy status, these results should be reassuring to pregnant women and clinicians, Dr. Harris said.

For the study, researchers did a retrospective analysis of data from patients in the Premier Healthcare Database, a repository of discharge records from 853 hospitals and from all payers that includes 20% of hospitalizations in the U.S.

Women included in the analysis ranged in age from 15 to 45 years old. Researchers excluded asymptomatic COVID-19 patients and focused instead only on individuals who had a viral pneumonia diagnosis.

Pregnant patients were typically younger, had fewer comorbidities, and were more likely to have public insurance than non-pregnant patients.

Limitations of the study include the fact that only hospitalized patients and in-hospital deaths were included, meaning results would not be generalizable to patients who were not hospitalized. Researchers also lacked data on lab tests to confirm COVID-19 diagnoses.

It's also not clear whether the indication for hospitalization in pregnant patients was for viral pneumonia or for delivery, said Dr. Emily Adhikari, an assistant professor of maternal-fetal medicine at UT Southwestern Medical Center, Dallas, and medical director of perinatal infectious diseases at Parkland Hospital.

"The pregnant patient might have milder symptoms of COVID-19 which were coded as viral pneumonia at the time of admission for delivery, and non-pregnant patients hospitalized with COVID-19 can't really be admitted for obstetric reasons," Dr. Adhikari, who wasn't involved in the study, said by email.

"So even though these are all hospitalized patients, you might be looking at two groups that differ in severity of illness," Dr. Adhikari said.

Pregnant women with COVID-19 might also be admitted earlier in the course of illness out of an abundance of caution, said Dr. Matthew Blitz, director of clinical research in maternal-fetal medicine at Northwell Health. Better outcomes were almost certainly not related to pregnancy itself but instead related to other underlying differences in the groups compared, Dr. Blitz, who wasn't involved in the study, said by email.

"Several studies have now convincingly demonstrated that pregnant women with COVID-19 are at increased risk for both maternal and fetal complications," Dr. Blitz said. "However, it's important to remember that most pregnant women are young and healthy and those who are infected usually recover without any serious problems."

SOURCE: Annals of Internal Medicine, published online May 10, 2021.