Rise of the Delta variant increases COVID-19 hospitalizations among unvaccinated pregnant women

Reviewed by Emily Henderson, B.Sc.Sep 30 2021

Unvaccinated pregnant women are increasingly being hospitalized with COVID-19 during a nationwide surge of the Delta variant, according to research from UT Southwestern Medical Center.

The study – which covers more than 1,500 cases in the Dallas area since May 2020 – offers a snapshot of what doctors believe is happening in communities across the country. The research shows the proportion of pregnant COVID-19 patients requiring hospitalization increased to 10 to 15% in late August and early September, more than double the percentage of last year before the emergence of the Delta variant.

"This is a concerning trend, and we're primarily seeing these cases in unvaccinated women," said Emily Adhikari, M.D., Assistant Professor of Obstetrics and Gynecology, and a lead author of the study published in the American Journal of Obstetrics and Gynecology.

Dr. Adhikari said the findings offer the first objective evidence that the case number and severity of illness in pregnant women rose with a spike in the Delta variant. The study included 1,515 pregnant women diagnosed with COVID-19 who received care from Parkland Health & Hospital System – Dallas County's public hospital – from May 2020 through Sept. 4, 2021.

Overall, 82 patients had severe or critical illness, including 10 requiring ventilators, and two deaths. The proportion of severe or critical cases was around 5% until after the new year, and were then largely nonexistent in February and most of March.

However, the rise of the Delta variant coincided with a new wave of hospitalizations that peaked this August and early September, including more than a third of COVID-19 cases the week of Aug. 29. By this time, genetic sequencing conducted at UT Southwestern showed nearly all the local variants sequenced were the Delta B.1.617.2 strain.

Of the 82 patients hospitalized since May 2020, all but one were unvaccinated.

Dr. Adhikari acknowledged that some women fear the vaccine may not be safe to take during pregnancy, but said research has debunked those concerns. She co-authored a JAMA article earlier this year that elaborated on the issue of vaccines and pregnancy.

Dr. Adhikari said pregnant women are at greater risk for complications with any type of severe respiratory infection, so these findings further emphasize the need for pregnant and lactating women in all communities to get vaccinated for COVID-19.

If they are exposed and infected, they run a higher risk of severe illness from this most recent Delta variant. Pregnant women should get immunized as soon as possible."

Dr. Emily Adhikari, Medical Director of Perinatal Infectious Diseases at Parkland

The genomic sequencing that revealed nearly all the local SARS-CoV-2 variants were Delta was performed in the McDermott Center Next Generation Sequencing (NGS) Core with analysis performed by the McDermott Bioinformatics Lab, both under the supervision of Helen H. Hobbs, M.D., a Howard Hughes Medical Institute investigator and Professor of Internal Medicine and Molecular Genetics, who directs the Eugene McDermott Center for Human Growth and Development at UT Southwestern. Jeffrey SoRelle, M.D., Assistant Professor of Pathology and a co-author on the study, is collaborating with Dr. Hobbs by providing all positive COVID-19 samples tested at UT Southwestern and interpreting sequencing results with support from a rapid, focused PCR-based test. The collaboration with the McDermott Center Next Generation Sequencing (NGS) Core at UT Southwestern allows whole genome whole sequencing of SARS-CoV-2 virus in a state-of-the-art facility that performs NGS coupled with bioinformatic analysis.