News Release

PHILADELPHIA – Depending on the specific type, bacteria in a woman’s vagina and cervix may increase the risk of premature birth or protect against it, according to new research from the Perelman School of Medicine at the University of Pennsylvania. Results of the study provide groundbreaking information that the authors suggest could help physicians learn how to prevent preterm birth, either by eliminating the “bad” bacteria, or increasing the “protective” bacteria. The study was presented this week at the Society for Maternal-Fetal Medicine’s annual meeting in Las Vegas, and received the March of Dimes Award for Best Abstract on Prematurity.

Premature birth (before 37 weeks of pregnancy) is the #1 killer of babies in the United States and the leading cause of death in children under age 5 around the world. Babies who survive an early birth often face serious and lifelong health problems, including breathing problems, jaundice, vision loss, cerebral palsy and intellectual delays. In addition to the human toll, preterm birth accounts for more than $26 billion annually in avoidable medical and societal costs, according to the National Academy of Medicine.

“For the first time in 8 years, the number of pre-term babies in the United States actually increased in 2016, and unfortunately, there are underlying causes that doctors still don't understand,” said lead author Michal Elovitz, MD, a professor Obstetrics & Gynecology at the Perelman School of Medicine at the University of Pennsylvania, director of the Maternal and Child Health Research Center at Penn, and a co-investigator for the March of Dimes’ Prematurity Research Center at the University of Pennsylvania. “Decoding the causes of prematurity has been a riddle that’s stumped researchers and clinicians for years, but our new study is finally shedding some light on a path toward offering treatment to women we can identify as being at-risk.”

In the study, researchers examined vaginal swabs from a sample of 2,000 pregnant women, taken at three distinct points in pregnancy, to determine the microbial colonies that were present. Analysis showed that among the many specific types of bacteria, some – such as certain bifidobacterium and lactobacillus species – actually lowered the risk of spontaneous preterm birth, while others – specifically several anaerobic bacteria – significantly increased the risk.

Elovitz says the new findings are the result of a multidisciplinary team of experts from immunology and microbiology, who came together and took a new approach to the issue, examining the cervix and vagina instead of limiting the scope of their study to the uterus, as conventional wisdom would suggest. The authors say more research is needed to confirm the findings, but if proven, it could mean treatments targeting “bad” cervical bacteria, or replenishing the “good” bacteria could be used to prevent premature birth in the immediate future.

Funding for the study was provided by the National Institutes of Health, and the National Institute of Nursing Research (R01NR014784).


Penn Medicine is one of the world’s leading academic medical centers, dedicated to the related missions of medical education, biomedical research, excellence in patient care, and community service. The organization consists of the University of Pennsylvania Health System and Penn’s Raymond and Ruth Perelman School of Medicine, founded in 1765 as the nation’s first medical school.

The Perelman School of Medicine is consistently among the nation's top recipients of funding from the National Institutes of Health, with $550 million awarded in the 2022 fiscal year. Home to a proud history of “firsts” in medicine, Penn Medicine teams have pioneered discoveries and innovations that have shaped modern medicine, including recent breakthroughs such as CAR T cell therapy for cancer and the mRNA technology used in COVID-19 vaccines.

The University of Pennsylvania Health System’s patient care facilities stretch from the Susquehanna River in Pennsylvania to the New Jersey shore. These include the Hospital of the University of Pennsylvania, Penn Presbyterian Medical Center, Chester County Hospital, Lancaster General Health, Penn Medicine Princeton Health, and Pennsylvania Hospital—the nation’s first hospital, founded in 1751. Additional facilities and enterprises include Good Shepherd Penn Partners, Penn Medicine at Home, Lancaster Behavioral Health Hospital, and Princeton House Behavioral Health, among others.

Penn Medicine is an $11.1 billion enterprise powered by more than 49,000 talented faculty and staff.

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