No increase found in stillbirth, preterm birth during pandemic

Two large JAMA studies yesterday found no increase in pandemic-related stillbirths or preterm births or among UK and US women.

A higher risk of infectious diseases has been documented in pregnant women—including respiratory infections and flu—leading to concerns about poorer pandemic-related pregnancy and birth outcomes. There have been confirmed cases of stillbirth deliveries among pregnant women with severe COVID-19, and a smaller previous UK study showed an increased risk.

UK stillbirth rate stable in 2020

In the first JAMA study, English public health researchers used national and regional hospitalization data in the annual Hospital Episode Statistics (HES) database to analyze stillbirth rates from April to June 2020, comparing them to baseline 2019 data. Stillbirths—fetal death after 24 weeks gestation—were identified using billing codes for delivery outcomes, but HES data did not include maternal demographic information, SARS-CoV-2 infection status, or differences in access to care.

The researchers identified 543 stillbirths from Apr 1 to Jun 30 (0.41% of all pregnancies; 95% confidence interval [CI], 0.38% to 0.45%) compared with 565 stillbirths during the same period in 2019 (0.40%; 95% CI, 0.37% to 0.44%). The overall risk of stillbirth was not significantly higher than in 2019 (incidence rate ratio [IRR], 1.02; 95% CI, 0.91 to 1.15; P = 0.69), and this remained the case when the researchers evaluated regional data (IRR ranges from 0.85 to 1.22).  

"There was no evidence of any increase in stillbirths regionally or nationally during the COVID-19 pandemic in England when compared with the same months in the previous year and despite variable community SARS-CoV-2 incidence rates in different regions," the study authors wrote.

"This contrasts with the findings from a single UK hospital and is reassuring given the concerns about patients, including pregnant women, receiving fewer services or being hesitant to access health care during the pandemic," they added.

The authors are referring to a Jul 10 JAMA study that reported higher stillbirth deliveries in a London hospital from Feb 1 to Jun 14 compared with baseline data.

No change in stillbirth, preterm birth in Philadelphia

The second JAMA study analyzed 2,992 live births at two Penn Medicine hospitals in Philadelphia from March through June 2020, comparing them with 5,875 births over the same period in 2018 and 2019. The study authors found no significant change in overall preterm or stillbirth rates during the pandemic, and no pandemic-related differences when preterm births were broken down by category—spontaneous or medically induced.

Children's Hospital of Philadelphia (CHOP) and University of Pennsylvania researchers used data from GeoBirth—an ongoing, racially diverse pregnancy database that has tracked more than 100,000 births in Philadelphia since 2008. The researchers compared rates of spontaneous and medically indicated preterm birth and stillbirth—defined as intrauterine demise after 20 weeks.

They found a 0.54% rate of stillbirth before the pandemic and a 0.50% rate during it.

In addition, the researchers classified 9.5% of pandemic births as preterm, compared with 10.5% among pre-pandemic births (adjusted difference [AD] -1.1%; 95% CI, -2.4% to 0.2%).

Spontaneous preterm births represented 4.7% of the total during the pandemic, versus 5.7% during the pre-pandemic period (AD, -1.1%; 95% CI, -2.4% to 0.2%), with no significant association between race/ethnicity for the comparison periods (P = 0.09). Medically indicated preterm births accounted for 5.0 per 1,000 pandemic births and 5.4 per 1,000 in the pre-pandemic period (AD, -0.03 per 1,000 births; 95% CI, -0.34 to 0.29).

"Preterm birth is highly complex, with a diverse set of presentations and unknown causes," said CHOP physician Heather H. Burris, MD, MPH, senior author of the study, in a CHOP news release yesterday.

"Because we have two independent reviewers assessing every preterm birth at two Penn Medicine hospitals, we were able to complete a rigorous analysis of multiple types of preterm birth for the first four months of the pandemic and compare that data to the same period in previous years."

The results of the new study differ from the findings in a demographically homogenous Danish study published Aug 11, which showed a lockdown-related decrease in preterm birth.

"While particular mechanisms that lead to preterm birth remain elusive, we know that various individual and environmental factors are linked to poor birth outcomes, and that those factors vary by demographic groups," coauthor Michal Elovitz, MD, of the University of Pennsylvania School of Medicine, said in the news release.

"Our years of work in this field led us to question other reports that suggested preterm births and stillbirths had decreased across the board over this extremely stressful and uncertain pandemic period," she added.

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