A new study from China has identified a possible link between gut health and preterm birth, suggesting that the presence of a common bacterium in pregnant women could increase the risk of early delivery.
The research, published this week in the journal Cell Host & Microbe, focused on Clostridium innocuum (C. innocuum), a gut bacterium found to produce an enzyme capable of breaking down estradiol, a hormone essential for maintaining pregnancy. Women carrying the bacterium in their gut microbiome were found to face a higher likelihood of giving birth before 37 weeks of pregnancy.
“Preterm birth is a leading cause of death in newborns and children under five,” said An Pan, an epidemiology professor at Huazhong University of Science and Technology and one of the study’s authors. “This study suggests that for pregnant women or those preparing to conceive, monitoring the gut microbiome may help prevent potential adverse outcomes.”
Preterm birth and its risks
According to the World Health Organization (WHO), preterm birth remains a major global health issue, accounting for around 900,000 deaths in children under five in 2019 alone. Babies born before 37 weeks often face breathing difficulties, developmental delays, and higher risks of long-term disabilities, particularly if born before 32 weeks.
While known risk factors include infections, diabetes, multiple pregnancies, and genetic influences, many preterm births have no clear cause. The Chinese study suggests that gut bacteria may represent a previously overlooked factor.
How the study was conducted
Researchers analyzed data from two large cohorts of more than 5,000 women in early and mid-pregnancy across China. Stool and blood samples were collected to study microbial composition, genetic variation, and hormone metabolism.
The team identified 11 microbial groups linked to preterm birth, with C. innocuum showing the strongest association. Laboratory analysis revealed that the bacterium produces an enzyme that depletes estradiol levels, potentially disrupting pathways critical to sustaining pregnancy.
“Estradiol regulates processes that support pregnancy and trigger childbirth,” explained Zelei Miao, a co-author from Westlake University. “We propose that dysregulated estradiol levels caused by C. innocuum could explain the link between the gut microbiome and preterm birth.”
Broader implications and caveats
The findings could pave the way for new approaches to monitoring pregnancy health, potentially using microbiome testing to flag higher-risk cases. However, researchers cautioned that their study was limited to Chinese cohorts, where preterm birth rates are relatively low. Since the gut microbiome is influenced by diet, environment, and genetics, further studies are needed in more diverse populations to confirm the results.
Despite these limitations, experts say the research highlights the gut microbiome as a potentially modifiable factor in reducing preterm births worldwide—a condition that remains one of the most pressing challenges in maternal and child health.
