SARS-CoV-2 infection in pregnancy and infant outcomes in the first year of life: a retrospective cohort study

Background — There are known maternal and obstetrical risks following SARS-CoV-2 infection in pregnancy, but the impact on offspring is not well known. The objective of this study was to examine offspring risks of hospitalization and emergency department visits in the first year of life following SARS-CoV-2 infection in pregnancy.

Methods — This was a retrospective cohort study in Ontario, Canada of infants born from March 1, 2020 to December 31, 2021 using health administrative databases. The exposure group was defined by a positive SARS-CoV-2 PCR test in pregnancy, while the comparator group included pregnancies without a positive test recorded. The primary outcomes included all-cause offspring hospitalizations and emergency department (ED) visits in the first year of life. Poisson regression was used to adjust for maternal sociodemographic factors, medical and obstetrical history, and health behaviours. The main secondary outcome was risk of infections (including respiratory, gastrointestinal and otitis media infections) in the first year of life. A sensitivity analysis was conducted in which individuals with a negative SARS-CoV-2 test served as the comparator group.

Results — There were 222,448 live births during the study period; following matching 45,958 pregnancies were included. Cases were matched on maternal age, geography, and last menstrual period date in a 10:1 ratio. The exposed group included 5,291 pregnancies and the comparator group included 40,667 pregnancies. There was no significant difference observed between groups in risk of hospitalization (aRR (95% CI): 1.10 (0.99–1.22)). Small increases in risk of both ED visits (aRR 1.12 (1.06–1.17)), and infections (aHR 1.16 (1.11–1.21) were observed in the exposed group. When the comparator group was limited to pregnancies with a negative SARS-CoV-2 test, there was no difference in risk of ED visits, but the increased risk of infections persisted.

Conclusions — A positive SARS-CoV-2 test in pregnancy was not associated with an increased risk of hospitalization in the offspring’s first year, which may be reassuring to parents and healthcare providers. However, there may be a small increased risk of offspring infections.