Changes in Adverse Pregnancy Outcomes Associated With the COVID-19 Pandemic in the United States

This cross-sectional study evaluates the change in rates of pregnancy complications during the COVID-19 pandemic among pregnant women with commercial health insurance across the US.


Introduction
The COVID-19 pandemic and ensuing government response has led to profound changes in lifestyle, physical and mental health, and health care access and delivery.2][3][4] Accordingly, we evaluated the change in rates of pregnancy complications associated with the pandemic period among pregnant women with commercial health insurance across the US.

Methods
This cross-sectional study involved analysis of deidentified data and was deemed nonhuman participants research by the institutional review board at Boston University, and, therefore, informed consent was waived.This analysis followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.
We identified medical claims indicative of a delivery (ie, International Statistical Classification of Diseases, Tenth Revision [ICD-10] Z37.xx) and adverse pregnancy outcomes, which have been previously defined (eAppendix in the Supplement). 5We analyzed claims from January 1, 2019, to December 31, 2020, from the OptumLabs Data Warehouse, a longitudinal database of deidentified administrative claims among commercial and Medicare Advantage enrollees throughout the US.
Claims separated by 182 days or more were considered separate pregnancies.
We defined the COVID-19 pandemic period as March 1 to December 31, 2020, and compared the proportion of deliveries with each adverse outcome during this period vs the analogous period in 2019 (ie, referent period).We obtained risk ratios (RR) and 95% CIs using Poisson regression with the logarithm of number of deliveries as an offset.We performed sensitivity analyses restricted to women who were continuously enrolled in a commercial health insurance plan from March 1, 2019, to December 31, 2020.We also examined geographic variation in the RR by fitting a separate model in each state and using a random-effects meta-analytic model to examine statistical heterogeneity across states.We conducted analyses in R version 3.6.1 (R Project for Statistical Computing) and considered a 2-sided P < .05 as statistically significant.Data analyses took place from May to August 2021.

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Discussion
To our knowledge, this is the largest and most comprehensive study to date of the impact of the COVID-19 pandemic on adverse pregnancy outcomes.Our finding that the pandemic period was not associated with a changing risk of stillbirth and provided only modest evidence of a lower risk of preterm birth is broadly consistent with the existing literature. 1,3Our study provides novel evidence of the association of the pandemic with the risk of complications that have rarely been documented, including gestational hypertension, poor fetal growth, and preeclampsia.
This study had limitations, including the reliance on billing codes from health care claims to ascertain complications of pregnancy, the lack of data on gestational age at the time of birth, and the inability to ascertain iatrogenic preterm deliveries and COVID-19 status.Our results may not generalize to pregnant women without commercial health insurance or those outside of the US.

Table .
Absolute and Relative Risk of Delivery With an Adverse Outcome During March 1 to December 31, 2020, vs the Same Period in 2019 a