Preterm Birth among Pregnant Persons with Severe Acute Respiratory Syndrome Coronavirus 2 Infection

Abstract

Background: Pregnant persons with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection are at increased risk of preterm birth, and evidence suggests this risk may be higher among pregnant persons with severe coronavirus disease 2019 (COVID-19) or among those infected later in pregnancy. However, the relationship between trimester of SARS-CoV-2 infection, severity of COVID-19, and preterm birth is not fully understood.Objective: This study examined the relationship between trimester of SARS-CoV-2 infection, illness severity, and risk for preterm birth after adjusting for maternal age, selected underlying conditions, and pregnancy complications.Study Design: Using a cohort of 6,396 pregnant persons with SARS-CoV-2 infection in 2020 identified through the Surveillance for Emerging Threats to Mothers and Babies Network, we analyzed data for those with infection at <37 weeks gestation who delivered a singleton liveborn infant. Illness severity groups (asymptomatic infection, mild, moderate-to-severe, and critical) were adapted from National Institutes of Health and World Health Organization criteria. Risk ratios for preterm birth (<37 weeks) were calculated for illness severity categories (referent=mild), trimester of SARS-CoV-2 infection (referent=first trimester), and illness severity stratified by trimester of infection adjusted for age, selected underlying medical conditions, and pregnancy complications.Results: Pregnant persons with critical COVID-19, compared to mild COVID-19, in the second (aRR 3.9; 95% CI: 1.7-9.0) or third (aRR 4.6; 95% CI: 3.2-6.6) trimester were at increased risk of preterm birth. Among persons infected in the second or third trimester, those with critical COVID-19 delivered sooner after infection compared with persons with mild COVID-19 (p<0.001 for second trimester and p=0.02 for third trimester). Nearly half of those with moderate-to-severe or critical COVID-19 delivered by cesarean, with most critical COVID-19 cesarean deliveries as emergent (76.6% weighted [65/96 unweighted]).Conclusion: When infection occurred in the second or third trimester, critical COVID-19 was associated with increased risk of preterm birth, and those with critical COVID-19 delivered sooner after infection compared to those with mild COVID-19. These findings can be used to guide prevention strategies, including vaccination, and inform clinical practices for pregnant persons, particularly those presenting with critical COVID-19 later in pregnancy.

Pregnancy and Infant Outcomes by Trimester of SARS-CoV-2 Infection in Pregnancy – SET-NET, 22 Jurisdictions, January 25, 2020 - December 31, 2020

“…1 A previous analysis of SET-NET data indicated that, among people with SARS-CoV-2 infection during pregnancy, critical COVID-19 illness was associated with an increased risk of preterm birth compared to those with mild-to-severe COVID-19 illness. 25 Differences in characteristics between pregnant people with and without SARS-COV-2 infection may explain the higher preterm rates in this cohort. 26 COVID-19 in pregnancy is associated with adverse fetal and infant outcomes in addition to risk of severe disease for the pregnant person themselves, necessitating access to safe and effective vaccines, as well as treatment.…”