For a study, researchers sought to report the maternal and perinatal outcomes of SARS-CoV-2 infection during pregnancy and identify characteristics linked to severe illness in the pregnant population. CANCOVID-Preg is a surveillance program in Canada for SARS-CoV-2–affected pregnancies. For the period March 1, 2020, to October 31, 2021, the study included experimental population-level data from six Canadian provinces. A total of 6,012 pregnant women with a positive SARS-CoV-2 polymerase chain reaction test result at any point during pregnancy (primarily due to symptomatic presentation) were included in the study, and they were compared to two contemporaneous groups of age-matched female SARS-CoV-2 infected pregnant women and unaffected pregnant women from the pandemic period.

The majority of SARS-CoV-2 cases were detected between 28 and 37 weeks of pregnancy among 6,012 pregnant women in Canada (median age, 31 [IQR, 28-35] years) (35.7%). Individuals who were not white were overrepresented. Pregnancy was linked to a higher risk of SARS-CoV-2–related hospitalization compared to SARS-CoV-2 cases in the general population of Canada (7.75% vs. 2.93%; relative risk, 2.65 [95% CI, 2.41-2.88]), as well as an increased risk of intensive care unit/critical care unit admission (2.01% vs. 0.37%; relative risk, 5.46 [95% CI, 4.50-6.53]). Maternal outcomes were substantially linked with increasing age, preexisting hypertension, and gestational age upon diagnosis. Even in cases of milder sickness not requiring hospitalization, the risk of preterm delivery was considerably higher in SARS-CoV-2–affected pregnancies (11.05% vs. 6.76%; relative risk, 1.63 [95% CI, 1.52-1.76]), compared to unaffected pregnancies over the same time.

SARS-CoV-2 infection during pregnancy was substantially related to an increased risk of unfavorable maternal outcomes and preterm delivery in this exploratory surveillance research conducted in Canada from March 2020 to October 2021.