Pregnant COVID-19 patients are about 40% more likely to develop serious complications or die than their uninfected peers, suggests a study led by University of Utah Health researchers published yesterday in JAMA.
The retrospective cohort study examined the outcomes of 41,104 women who delivered at 17 US hospitals from Mar 1 to Dec 31, 2020, following them up to Feb 11, 2021. Among the patients, 2,352 had COVID-19 and 11,752 did not.
Most women (80.1%) tested positive for COVID-19 in the third trimester, while 17.6% were in the second trimester, and 2.3% were in the third trimester. Among the 103 patients (4.4%) who first tested positive after delivery, the median timing was 18 days after delivery.
Among patients testing positive, 58 (2.5%) did so more than 2 weeks after delivery. COVID-19 was categorized as critical in 59 patients (2.5%), severe in 180 (7.7%), moderate in 347 (14.8%), mild in 728 (31.0%), and asymptomatic in 1,038 (44.1%).
Risks for cesarean birth, ICU admission
Relative to uninfected patients, those diagnosed as having COVID-19 were significantly more likely to die or become seriously ill because of high blood pressure-related pregnancy disorders, postpartum hemorrhage, or other respiratory infection (13.4% vs 9.2%; adjusted relative risk [aRR], 1.41). All five maternal deaths occurred in COVID-positive women.
"We already knew that pregnant people are at higher risk for the complications of COVID-19 itself," lead study author Torri Metz, MD, said in a University of Utah Health news release. "Our research is among the first to find that infection with SARS-CoV-2 can elevate the risk of serious consequences related to progression of common pregnancy complications."
Moderate to severe COVID-19, compared with asymptomatic or mild illness, was significantly tied to serious maternal illness, cesarean birth (45.4% vs 32.4%), intensive care unit (ICU) admission (12.8% vs 1.2%), and death (26.1% vs 9.2%).
Patients with asymptomatic or mild infection were at significantly higher risk for superficial or deep surgical-site infection (1.8% vs 0.7%; RR, 2.55) and high blood pressure–related pregnancy disorders (7.1% vs 6.5%; aRR, 1.28).
Other adverse maternal outcomes, including the need for mechanical ventilation, vasopressor support for treating low blood pressure, cardiomyopathy (disease of the heart muscle), and venous thromboembolism (blood clots), were significantly more common among COVID-19 patients than their uninfected counterparts. All four patients who needed extracorporeal membrane oxygenation had COVID-19.
Odds for preterm birth, NICU admission
A total of 14,471 newborns were included in the analysis; 2,297 were delivered by women who had COVID-19 while pregnant, and 12,017 were born to uninfected women. SARS-CoV-2 exposure was significantly linked to preterm birth at less than 37 weeks' gestation (17.7% vs 14.1%; aRR, 1.15) and to admission to a neonatal ICU (22.0% vs 17.8%; aRR, 1.15).
Most preterm births among COVID-19 patients were medically indicated or didn't result from spontaneous preterm labor (58.8%). COVID-19 was the indication for preterm birth in 8.3% of women who had a medically indicated preterm birth. Among 1,323 live births to COVID-19 patients, 1.2% of neonates tested positive for COVID-19 before hospital release.
Overall, COVID-19 infection was not significantly linked with cesarean birth (34.7% vs 32.4%; aRR, 1.05), and 1,766 patients with asymptomatic or mild infections were not more likely to become seriously ill or die (9.2% vs 9.2%; aRR, 1.11) or to give birth via cesarean (31.2% vs 32.4%; aRR, 1.00). Patients with moderate or severe COVID-19, however, were prone to cesarean delivery (45.4% vs 32.4%; aRR, 1.17).
"Some pregnant individuals who have COVID-19 are just too sick for us to attempt a vaginal birth," Metz said. "In certain circumstances, such as the onset of preeclampsia [high maternal blood pressure leading to seizures], the fetus is also far less likely to tolerate it."
Previous cesarean birth was the reason for cesarean birth in 28.9% of COVID-infection women, compared with 28.6% of their negative peers. Among infected women, 2.3% of the cesarean births were indicated for COVID-19.
"We know from other studies that vaccination prevents the most severe symptoms of the disease," Metz said. "So, this is just another piece of the puzzle that should encourage pregnant people to get vaccinated."