SARS-CoV-2 infection during pregnancy and preterm birth in Massachusetts from March 2020 through March 2021.

BACKGROUND: SARS-CoV-2 infection during pregnancy has been linked to preterm birth, but this association is not well understood. OBJECTIVES: To examine the association between SARS-CoV-2 infection and spontaneous and provider-initiated preterm birth (PTB), and how timing of infection, and race/ethnicity as a marker of structural inequality, may modify this association. METHODS: We conducted a retrospective cohort study among pregnant people who delivered singleton, liveborn infants (22-44 weeks gestation) from 1 March 2020 to 31 March 2021 (n = 68,288). We used Cox proportional hazards models to compare the hazard of PTB between pregnant people with and without laboratory-confirmed SARS-CoV-2 infection during pregnancy. We evaluated this association according to the trimester of infection, timing from infection to birth, and timing of PTB. We also examined the joint associations of SARS-CoV-2 infection and race/ethnicity with PTB using the relative excess risk due to interaction (RERI). RESULTS: Positive SARS-CoV-2 tests were identified for 2195 pregnant people (3.2%). The prevalence of PTB was 7.2% (3.8% spontaneous, 3.6% provider-initiated). SARS-CoV-2 infection during pregnancy was associated with an increased risk of PTB overall (adjusted hazard ratio [HR] 1.53, 95% confidence interval [CI] 1.34, 1.74), and provider-initiated PTB (HR 1.79, 95% CI 1.50, 2.12) but not spontaneous PTB (HR 1.09, 95% CI 0.89, 1.36). Second trimester infections were associated with an increased risk of provider-initiated PTB, and third trimester infections were associated with an increased risk of both PTB subtypes. A joint inverse association between White non-Hispanic race/ethnicity and SARS-CoV-2 infection and spontaneous PTB (HR 0.56, 95% CI 0.34, 0.94; RERI -0.6, 95% CI -1.0, -0.2) was also observed. CONCLUSIONS: SARS-CoV-2 infections were primarily associated with an increased risk for provider-initiated PTB in this study. These findings highlight the importance of promoting infection-prevention strategies among pregnant people.

Characteristics of People With and Without Laboratory-Confirmed SARS-CoV-2 Infection During Pregnancy, Massachusetts, March 2020-March 2021.

OBJECTIVES: Pregnant people infected with SARS-CoV-2, the virus that causes COVID-19, are at increased risk for severe illness and death compared with nonpregnant people. However, population-based information comparing characteristics of people with and without laboratory-confirmed SARS-CoV-2 infection during pregnancy is limited. We compared the characteristics of people with and without SARS-CoV-2 infection during pregnancy in Massachusetts. METHODS: We compared maternal demographic characteristics, pre-pregnancy conditions, and pregnancy complications of people with and without SARS-CoV-2 infection during pregnancy with completed pregnancies resulting in a live birth in Massachusetts during March 1, 2020-March 31, 2021. We tested for significant differences in the distribution of characteristics of pregnant people by SARS-CoV-2 infection status overall and stratified by race and ethnicity. We used modified Poisson regression analyses to examine the association between race and ethnicity and SARS-CoV-2 infection during pregnancy. RESULTS: Of 69 960 completed pregnancies identified during the study period, 3119 (4.5%) had laboratory-confirmed SARS-CoV-2 infection during pregnancy. Risk for SARS-CoV-2 infection was higher among Hispanic (adjusted risk ratio [aRR] = 2.3; 95% CI, 2.1-2.6) and non-Hispanic Black (aRR = 1.9; 95% CI, 1.7-2.1) pregnant people compared with non-Hispanic White pregnant people. CONCLUSIONS: This study demonstrates the disproportionate impact of SARS-CoV-2 infection on Hispanic and non-Hispanic Black pregnant people in Massachusetts, which may widen existent inequities in maternal morbidity and mortality. Future research is needed to elucidate the structural factors leading to these inequities.

Birth and Infant Outcomes Following Laboratory-Confirmed SARS-CoV-2 Infection in Pregnancy - SET-NET, 16 Jurisdictions, March 29-October 14, 2020.

Pregnant women with coronavirus disease 2019 (COVID-19) are at increased risk for severe illness and might be at risk for preterm birth (1-3). The full impact of infection with SARS-CoV-2, the virus that causes COVID-19, in pregnancy is unknown. Public health jurisdictions report information, including pregnancy status, on confirmed and probable COVID-19 cases to CDC through the National Notifiable Diseases Surveillance System.* Through the Surveillance for Emerging Threats to Mothers and Babies Network (SET-NET), 16 jurisdictions collected supplementary information on pregnancy and infant outcomes among 5,252 women with laboratory-confirmed SARS-CoV-2 infection reported during March 29-October 14, 2020. Among 3,912 live births with known gestational age, 12.9% were preterm (<37 weeks), higher than the reported 10.2% among the general U.S. population in 2019 (4). Among 610 infants (21.3%) with reported SARS-CoV-2 test results, perinatal infection was infrequent (2.6%) and occurred primarily among infants whose mother had SARS-CoV-2 infection identified within 1 week of delivery. Because the majority of pregnant women with COVID-19 reported thus far experienced infection in the third trimester, ongoing surveillance is needed to assess effects of infections in early pregnancy, as well the longer-term outcomes of exposed infants. These findings can inform neonatal testing recommendations, clinical practice, and public health action and can be used by health care providers to counsel pregnant women on the risks of SARS-CoV-2 infection, including preterm births. Pregnant women and their household members should follow recommended infection prevention measures, including wearing a mask, social distancing, and frequent handwashing when going out or interacting with others or if there is a person within the household who has had exposure to COVID-19.†.