Project Summary

This research project is in progress. PCORI will post the research findings on this page within 90 days after the results are final.

What is the research about?

Severe maternal morbidity, or SMM, refers to unexpected outcomes of labor and delivery that pose serious risks to the mother and baby. SMM includes health problems such as heart failure, sepsis, and blood clots. Black women are at increased risk of SMM compared with White women.

Pregnant women with genital herpes have an increased risk of SMM. Medicine may help reduce this risk. Because Black women have a higher rate of genital herpes infection than White women, treating herpes infections during pregnancy may also help reduce racial disparities in SMM.

In this study, the research team is looking to see if treating herpes infection during pregnancy helps reduce disparities in SMM between Black and White women. The team also wants to know if starting treatment for herpes infection earlier is more effective at reducing racial disparities in SMM than treating infection during the third trimester. Current guidelines recommend treating herpes in the third trimester to prevent the baby from becoming infected. But this timing may be too late to prevent SMM.

Who can this research help?

Results may help doctors and patients when deciding on the best time to treat herpes in pregnancy.

What is the research team doing?

The research team is using clinical data from electronic health records, or EHRs, for 339,000 pregnant women. Based on whether women have herpes and whether they received treatment, the team is creating four groups:

  • Women with herpes who received treatment before the third trimester
  • Women with herpes who received treatment during the third trimester
  • Women with herpes who didn’t receive treatment during pregnancy
  • Women without herpes

Next, the research team is comparing rates of SMM across these groups. The team is also comparing rates of SMM between Black and White women.

Lastly, the research team is selecting a group of 1,200 women from the four groups by chance to take part in interviews. The team wants to learn more about risk factors that could affect SMM, such as whether women had a past pregnancy. The team is looking to see how these risk factors affect study results.

Patients who have had herpes during pregnancy, doctors, and advocacy groups are helping to plan and conduct this study.

Research methods at a glance

Design Element Description
Design Observational: cohort study
Population 339,000 pregnant women who are members of Kaiser Permanente of Northern California
  • Treatment for genital herpes before third trimester
  • Treatment for genital herpes during third trimester
  • Untreated genital herpes
  • Pregnant adults (controls) without genital herpes with no treatment

Primary: SMM (based on the Centers for Disease Control and Prevention’s 21 indicators)

Timeframe Timeframe Length of follow-up for collecting data on primary outcomes. View Glossary Immediate follow-up after delivery for primary outcome

Project Information

De-Kun Li, MD, MPH, PHD
Kaiser Foundation Research Institute, a Division of Kaiser Foundation Hospitals
Comparative Effectiveness of Treating Genital Herpes Infection to Reduce Racial Disparities in the Risk of Severe Maternal Morbidity (SMM)

Key Dates

April 2026

Study Registration Information


Award Type
Health Conditions Health Conditions These are the broad terms we use to categorize our funded research studies; specific diseases or conditions are included within the appropriate larger category. Note: not all of our funded projects focus on a single disease or condition; some touch on multiple diseases or conditions, research methods, or broader health system interventions. Such projects won’t be listed by a primary disease/condition and so won’t appear if you use this filter tool to find them. View Glossary
Populations Populations PCORI is interested in research that seeks to better understand how different clinical and health system options work for different people. These populations are frequently studied in our portfolio or identified as being of interest by our stakeholders. View Glossary
Intervention Strategy Intervention Strategies PCORI funds comparative clinical effectiveness research (CER) studies that compare two or more options or approaches to health care, or that compare different ways of delivering or receiving care. View Glossary
State State The state where the project originates, or where the primary institution or organization is located. View Glossary
Last updated: April 12, 2024