A new study from UTHealth Houston found that the common sexually transmitted disease Mycoplasma genitalium (also known as MGen) does not appear to increase the risk of recurrent preterm birth.
The survey results are American College of Obstetricians and Gynecologists.
Mycoplasma genitalis is a common sexually transmitted disease caused by small bacteria that can infect the urethra and reproductive tract. Most people with this disease have no symptoms, but when they do, they can cause irritation and inflammation that requires treatment.
Preterm birth is defined as birth before 37 weeks and is the leading cause of infant morbidity and death. Previous studies have suggested that certain Mycoplasma species may contribute to preterm birth, but those studies have been limited.
These findings provide important new insights into the role of Mycoplasma genitalium in pregnancy. Given the association between HIV infection and increasing antimicrobial resistance, continued research into this emerging infectious disease remains an important public health priority. ”
Eileen Stafford, MD, MPH, lead author of the study and assistant professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School, Texas State University Health Houston
Mycoplasmas are a group of small bacteria that can live in the reproductive tract. Unlike most bacteria, bacteria do not have a cell wall, making them difficult to detect and treat. Because Mycoplasma genitalium is associated with inflammation, researchers wondered whether Mycoplasma genitalium might be involved in pregnancy complications such as repeated preterm births.
To better understand this association, researchers conducted the first prospective study of its kind in nearly 500 pregnant women with a history of preterm birth or related complications. Patients were enrolled from July 2023 to December 2025. Participants were tested for Mycoplasma genitalium during the first trimester using an FDA-approved vaginal swab test.
The study found that 12% of participants tested positive for Mycoplasma genitalium. This infection was significantly more common among people who had previously given birth prematurely. However, Mycoplasma genitalium did not increase the risk of another spontaneous preterm birth or second trimester loss due to cervical insufficiency, which was also investigated in this study.
The results of this study suggest that while Mycoplasma genitalium may be associated with complications of previous pregnancies, it does not appear to cause recurrent preterm birth in subsequent pregnancies. Researchers note that Mycoplasma genitalium may pose a greater risk during initial or incidental infections, when the body’s immune response has not yet developed.
“This study provides important clarity for patients and clinicians,” said Stafford, a maternal-fetal medicine physician. “For people who are already at high risk for preterm birth, Mycoplasma genitalium infection alone is unlikely to increase the likelihood of preterm birth again.”
The researchers emphasize that more research is needed, as preterm birth is complex and influenced by many factors. Still, these results are reassuring and can help guide future screening and treatment decisions.
Other UT Health Houston researchers on this study include Sean Blackwell, MD; Dr. Hanyang Chen. Sahana Kodali, Bachelor of Science; and Mason Colley, Bachelor of Science.
Additional contributors are Dr. Erik Munson of Marquette University and Dr. Damon Getman of Hologic Inc.
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University of Texas Health Science Center at Houston
Reference magazines:
Stafford, Iowa, others. (2026). Mycoplasma genitalium infection and adverse perinatal outcomes. Journal of the American College of Obstetricians and Gynecologists. DOI: 10.1016/j.ajog.2026.04.041. https://www.sciencedirect.com/science/article/abs/pii/S0002937826002450?dgcid=author
