key: cord-0957090-23i62c2c
authors: Chen, Jiajia; Ferre, Cynthia; Ouyang, Lijing; Mohamoud, Yousra; Barfield, Wanda; Cox, Shanna
title: Changes and Geographic Variation in Rates of Preterm Birth and Stillbirth during the COVID-19 Pandemic According to Health Insurance Claims in the United States, April-June 2019-2020
date: 2021-10-14
journal: Am J Obstet Gynecol MFM
DOI: 10.1016/j.ajogmf.2021.100508
sha: 6c4d66e773c3939cb12af10cfd90d868837e94e3
doc_id: 957090
cord_uid: 23i62c2c

nan

Studies from Europe 1 reported a reduction in preterm birth rates early in the COVID-19 pandemic, but data from other world regions offered conflicting evidence 2 . In the United States, evidence on preterm birth and stillbirth rates during the pandemic is also mixed [3] [4] . Existing studies were often limited to specific US hospitals, states, or missing information on stillbirth. We examined temporal changes in US preterm birth and stillbirth rates comparing pre-pandemic rates with those during a period of reduced population movement (lockdown) and investigated the geographic variation in the changes by census regions.

We used IQVIA's PharMetrics Plus database, a large convenience sample of claims data that included about one-fifth of US births covered by commercial health insurance, to compare rates between the lockdown period (April-June 2020) and a comparison period (April-June 2019). We identified singleton delivery hospitalizations ≥20 weeks gestation using ICD-10 and CPT codes. We extracted information on weeks of gestation and birth outcomes (live birth or stillbirth) for each delivery. Preterm birth rates (born <37 gestation weeks), late (34-36 weeks), and early preterm birth (<34 weeks) were examined.

Stillbirth rates were also examined. We used logistic regression to compare birth outcome rates between both time periods, adjusting for census region and maternal age. While race/ethnicity data were available through data linkages for 12% of the sample, the missing/unknown category in the linked data was still more than 30%, limiting our ability to adjust or stratify by this variable. We reported adjusted rate measured in percentage point (%), adjusted rate difference (ARD), and adjusted rate ratio (ARR) using predictive margins from each regression model. To examine geographic variation, we used interaction terms between the indicator variables for time period and census region.

The adjusted rate of preterm birth during the 2020 lockdown was lower than the adjusted rate during the same months in 2019 (7.0% vs. 7.4%; ARD = -0.4%, 95% CI [-0.6%, -0.1%]). There was no change in the adjusted rate of stillbirth (ARD =-0.02%, 95% CI [-0.07%, 0.02%]). The reduction in preterm birth was driven by the decrease in late preterm birth (ARD = -0.3%, 95% CI [-0.6%, -0.1%]) (Panel A, Table 1 ). The largest reduction in preterm birth was in the Northeast (ARD = -1.1, 95% CI [-1.8%, -0.5%]) (Panel B, Table 1 ).

This study reported a decrease in US preterm birth rate by 0.4 percentage points during the COVID-19

lockdown period compared with a similar period in the previous year using a sample of delivery hospitalizations covered by private health insurance. Decreases were greatest in the Northeast region.

No changes were observed in stillbirth rates. The reduction was notable because the overall US preterm birth rate increased annually from 2014-2019 5 . This study has limitations. Our results did not adjust for maternal characteristics other than age. The source database comprised a convenience sample of privately-insured individuals, which may impact representativeness. Understanding patterns of adverse birth outcomes before and after the pandemic could help identify opportunities for prevention. 

Effects of the COVID-19 pandemic on maternal and perinatal outcomes: a systematic review and meta-analysis. The Lancet Global Health

Change in the incidence of stillbirth and preterm delivery during the COVID-19 pandemic

Association of preterm birth rate with COVID-19 statewide stay-at-home orders in Tennessee

Singleton preterm birth rates for racial and ethnic groups during the coronavirus disease 2019 pandemic in California

Vital statistics rapid release

Notes: In Panel A, each row shows predicted rates, rate difference, and rate ratio using predictive margins from the same logistic regression, with the dependent variables (preterm birth, late preterm birth, early preterm birth, and any stillbirth) shown on the left-hand side. In Panel B, all predicted rates, rate difference, and rate ratio were obtained from the same logistic regression, and the dependent variable is preterm birth rate. 95% confidence intervals in brackets. All regressions adjusted for indicators for year (2019 and 2020), age group in years