Link Implicated Between Bacteria and Premature Birth

Premature Baby in HospitalAccording to a new study published in the journal PLOS ONE, bacteria may cause premature preterm rupture of membranes (PPROM) in pregnant women, often leading to the premature birth of the baby.

Researchers in the Department of Obstetrics and Gynecology at the Vanderbilt University Medical Center in Nashville, Tennessee and at the Duke University Medical Center in Durham, North Carolina recently examined bacteria levels in relation to fetal membrane chorion thinning in PPROM, preterm, and term babies.

The fetal membranes, or water sac, play an important role in protecting the developing baby inside the womb. The fetal membranes consist of two layers, the amnion and the chorion. The amnion is the inner membrane that contains the amniotic fluid and the fetus. The chorion is the outer membrane that contains the amnion and is part of the placenta.

PPROM occurs when the fetal membranes rupture (water breaks) prematurely, or prior to 36 weeks of gestation. As Amy P. Murtha, an associate professor of obstetrics and gynecology at Duke University School of Medicine, explains:

“Complications of preterm births can have long-term health effects for both mothers and children. Our research focuses on why the fetal membranes, or water sac, break early in some women, with the overall goal of better understanding the mechanisms of preterm membrane rupture.”

PPROM accounts for nearly one-third of premature births.

In a previous study, Prof. Murtha and her colleagues discovered that infection is linked to a higher rate of cell death in the chorion, which can result in PPROM.

In the present study, the researchers discovered that pregnant women who suffer from PPROM tend to have thinner chorions. Mothers with chorioamnionitis, an inflammation of the fetal membranes due to a bacterial infection, had the highest rate of chorion cell deaths.

To determine if any patterns between presence of bacteria and membrane thinning existed, the researchers collected samples from 48 women after the women gave birth. The participants included women who gave birth at term and preterm and women with PPROM.

The researchers then measured the amount of thinning in the chorion membrane as well as the the presence of bacteria, both near and far from the rupture.

In all the subjects, the chorion was thinner at the site of the rupture. In the subjects who experienced PPROM, the chorion was thinner overall, not just at the site of the rupture.

Furthermore, despite previous thought that the fetal membranes create a sterile environment, bacteria were present in all the samples. Unsurprisingly, bacteria levels were also higher at the site of the rupture. Additionally, women who experienced PPROM had the highest levels of bacteria at both the site of the rupture and at other locations on the sac. The most bacteria were present at the thinnest areas of the chorion.

The results of this study establish a link between bacteria and early rupturing of the fetal membranes. However, Prof. Murtha cautions that the link is not yet causal:

“We still know little about changes occurring within the fetal membrane in the presence of bacteria, but our data suggest the chorion and its thinning may be the battleground for these changes.”

If researchers can determine that increased bacteria levels are responsible for PPROM and can determine which bacteria are responsible, then preventive treatments and screening tools can be used to prevent PPROM.

Prof. Murtha concludes:

“For instance, if we think that certain bacteria are associated with premature rupturing of the membranes, we can screen for this bacteria early in pregnancy. We then might be able to treat affected women with antibiotics and reduce their risk for PPROM. Our research is several steps away from this, but it gives us opportunities to explore potential targeted therapeutic interventions, which we lack in obstetrics.”

More research still needs to be conducted on the link between bacteria and premature birth.


Bacteria ‘Could Be a Cause of Preterm Births’:
Bacteria Linked to Water Breaking Prematurely During Pregnancy:
Bacteria Localization and Chorion Thinning among Preterm Premature Rupture of Membranes:

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