What do expectant mothers' gum diseases have to do with premature births?
The long-established relationship between maternal gingivitis and neonatal health remains a scientific mystery. But new findings reported in Science Translational Medicine have helped scientists start conceiving some ideas around the potential connection—ideas that could eventually improve diagnoses of diseases affecting unborn babies.
It was long thought that we spend our prenatal existences wrapped in the hospital gurney-like sterility of a bacteria-free placenta. But as science has gradually come to grips with the vast ecosystems of bacteria that pervade our entire bodies, the notion of a sterile placenta has, during the past decade or so, faded away.
It was long thought that we spend our prenatal existences wrapped in the hospital gurney-like sterility of a bacteria-free placenta. But the notion of a sterile placenta has, during the past decade or so, faded away.
To get a clearer look at the intercellular bacteria that tend to congregate along the basal plate, where the maternal immune system intersects with the placenta, a team of Texas-based researchers used PowerSoil DNA isolation kits to study frozen placental tissue. The scientists found that the concentration of microbes in the samples was lower than in other parts of the body. But it certainly wasn't free of microbes. The team discovered non-disease causing communities of bacteria dominated by the same phyla that have been discovered in the microbial ecosystems of our mouths—albeit at lower concentrations.
The placental microbial communities more closely matched the make-up of our mouths than those of any other parts of the body analyzed—including, perhaps surprisingly, the vagina.
"We were surprised to see the overlap in some of the shared communities between the oral microbiome and the placental microbiome," says Kjersti Aagaard, an associate professor at the Baylor College of Medicine and one of the authors of the new paper. "We know there's a relationship between oral health and, at the least, pre-term birth—that data has been around for decades. When faced with that data, this [finding] actually makes some sense."
This field of research is young, and at this point, Aagaard and her colleagues can only speculate on the purpose of placentas' bacterial alliances.
"We think that it's probably important for early feeding of the infant," Aagaard says. "That's the site of glucose exchange, fatty acid transport, and lipid transport between the maternal circulation and the fetus. So maybe a part of what happens is that the bacteria is important for enabling those processes."
Ongoing research could eventually help researchers and doctors pinpoint signals of diseases afflicting unborn babies.
"When we think about very complex diseases, one thing we spend a lot of time thinking about is pre-term birth," Aagaard says. "We don’t know where the signal is going to come from that may herald somebody is at risk. A lot of the focus has been around the vagina, but we don’t really know—is that the best place to pick up that signal?"