SARS-CoV-2 and pregnancy outcomes during universal and non-universal testing in Sweden: register-based nationwide cohort study – Stephansson – – BJOG: An International Journal of Obstetrics & Gynecology
Goal
To assess the association between SARS-CoV-2 infection and pregnancy outcomes in terms of test policy and test-positivity-to-delivery interval.
Design
Nationwide cohort study.
Environment
Sweden.
Population
From the pregnancy register, we identified 88,593 single births, 11 March 2020-31 January 2021, linked to data on SARS-CoV-2 positivity from the Swedish Public Health Agency and information on neonatal care admission from the neonatal quality register. Adjusted odds ratios (aOR) were estimated stratified by test policy and test-positivity-to-delivery intervals.
Main performance measures
5-minute Apgar score, neonatal hospitalization, stillbirth and premature birth.
Results
During pregnancy, the SARS-CoV-2 test positivity was 5.4% (794/14 665) during universal and 1.9% (1402/73 928) during non-universal testing. There were generally lower risks associated with SARS-CoV-2 during universal than non-universal tests. In women who tested positive> 10 days after delivery, no significant differences in risk were generally observed during any of the test policies. Neonatal hospitalization was more common (15.3% vs. 8.0%; aOR 2.24, 1.62-3.11) in women who tested positive ≤10 days before delivery during universal testing. There was no significant association with 5-minute Apgar score <7 (1.0% vs. 1.7%; aOR 0.64, 0.24-1.72) or stillbirth (0.3% vs. 0, 4%; aOR 0.72, 0.10-5.20). Compared with preterm births (2.1%), the test positivity was higher in medically indicated preterm birth (5.7%; aOR 2.70, 1.60-4.58) but not significantly increased in spontaneous preterm birth (2.3%; aOR 1.12, 0.62-2.02).
Conclusions
Test policy and timing of test positivity affect the relationship between SARS-CoV-2 positivity and pregnancy outcomes. During non-universal testing, women with complications close to childbirth are more likely to be tested than women without complications, which increases the association with unfavorable pregnancy outcomes compared with findings during universal tests.