Bacteria linked to cancer now associated with deadly pregnancy complication
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A gut bacteria that has been linked to cancer has now also been connected to preterm births among pregnant women.
Researchers from Huazhong University of Science and Technology in China looked at stool samples from more than 5,000 pregnant women.
From their analysis, they found that women who had higher levels of the bacterial species Clostridium innocuum - a small, rod-shaped bacteria - were more likely to have preterm births - births before 37 weeks of pregnancy.
A further study of C. innocuum revealed that this species makes an enzyme that degrades estradiol - the most potent form of estrogen that plays a pivotal role during pregnancy.
Estrogen helps the uterus grow, maintains uterine lining, regulates key hormones and triggers the development of baby's organs. Low levels of the hormone in early pregnancy are associated with an elevated risk of miscarriage.
The researchers believe that low estradiol levels caused by high levels of C. innocuum living in the gut could be behind the increased risk of preterm birth.
And previous research has shown a correlation between cancer and C. innocuum, which can promote chronic inflammation - a known risk factor for the disease.
Kelly Spill Bonito from New Jersey was 27 years old when she found blood in her stool while pregnant with her first child. It turned out to be stage 3 colon cancer
In the new study, researchers used samples and data from two large pregnancy cohorts - the Tongji-Huaxi-Shuangliu Birth cohort from southwest China and the Westlake Precision Birth cohort from southeast China.
For the first cohort, the team collected stool samples from 4,286 participants in early pregnancy, at an average of 10.4 gestational weeks.
For the second cohort, they collected stool samples from 1,027 participants in mid-pregnancy, or around 26 gestational weeks.
They also collected blood samples from all participants, which were used to measure human genetic variations and hormone metabolism.
The researchers only looked at the link between different types of gut bacteria and preterm birth and they did not distinguish a link with other conditions.
The results suggested women who deliver preterm exhibit high levels of the gut bacteria as early as the first trimester.
While pregnant, a woman's immune system is suppressed to prevent her body from rejecting the fetus but the scientists believe C. innocuum could trigger preterm birth as it activates an immune response.
Commenting on the findings of their analysis, first author Zelei Miao of Westlake University, said: 'Estradiol regulates critical pathways that sustain pregnancy and initiate the process of childbirth.'
Researchers from Huazhong University of Science and Technology in China looked at stool samples from more than 5,000 pregnant women. From their analysis, they found that women who had higher levels of the bacterial species Clostridium innocuum - a small, rod-shaped bacteria - were more likely to have preterm births, which is before 37 weeks of pregnancy
About one out of every 10 births in the world is premature and this results in one million child deaths per year.
Therefore, the finding that C. innocuum disrupts estradiol 'could be the mechanism that links the gut microbiome to preterm birth.'
Corresponding author An Pan of Huazhong University of Science and Technology, highlighted that preterm birth is a leading cause of death in newborns and children under five.
He said the study suggests that for pregnant women or women preparing to become pregnant, it 'may be important to monitor their gut microbiome to prevent potential adverse pregnancy outcomes.'
About one out of every 10 births in the world is premature and this results in one million child deaths per year.
Along with drug use, other reasons for pre-term births can include chronic health conditions such as diabetes or heart disease, expecting multiples (about 60 percent of twins and triplets are born prematurely), and vaginal bleeding or infections during pregnancy.
One study by Icahn School of Medicine found that women who give birth to a premature baby have a 1.7-fold and 2.2-fold increased risk of death from any cause, respectively, during the next 10 years compared with those who deliver full term.
And the risk of an early death persists for up to 40 years after delivery, say researchers.
Women who deliver pre-term or extremely pre-term, defined as after 22 to 27 weeks of pregnancy, have been reported to have increased risks of developing conditions including heart disease or diabetes in later life.
Studies have also shown that estrogen has a protective effect in colon cancer development due to its anti-inflammatory properties. Therefore, if estrogen levels are jeopardized due to the presence of C. innocuum (pictured), it could put people at higher risk of colon cancer
The researchers note that because their study was based on two China-based cohorts with a relatively low prevalence of preterm birth, the findings may not be generalizable to other populations.
However, they hope to better understand how Clostridium innocuum impacts preterm birth risk to develop intervention and treatment strategies.
Also, their future line of work will look at how the bacteria works with estrogen to regulate health beyond pregnancy.
The findings were published in the Cell Press journal Cell Host & Microbe.
Daily Mail
