Premature birth affects 450,000 U.S. babies each year and is the leading cause of newborn deaths. But in about half of cases, doctors never figure out what triggered premature labor in the pregnant mom.
Now, there's a new clue: A Stanford study, published today, gives important details of how the microbiome - the body's community of bacteria - behaves in women whose pregnancies go to the full 40-week term, and what's different in women whose babies come three weeks, or more, early. A specific pattern of vaginal bacteria was linked to greater risk of preterm delivery, and the longer the pattern persisted, the greater the risk, the study found.
The work is one piece of a larger effort by the March of Dimes Prematurity Research Center at Stanford to bring experts from many branches of science together to work on preterm birth. The researchers collected weekly bacterial samples throughout pregnancy from four body sites for 49 pregnant women, of whom 15 delivered prematurely. Patterns of vaginal bacteria that were dominated by lactobacillus bacteria were linked to low prematurity risk. Such patterns had already been shown to be linked to health in non-pregnant women.
A pattern of high bacterial diversity, low lactobacillus and high levels of gardnerella and ureaplasma bacteria was linked to higher prematurity risk, the study also showed. This was especially true if the high-diversity pattern persisted for several weeks. From our press release about the new research:
“I think our data suggest that if the microbiome plays a role in premature birth, it may be something that is long in the making,” said the study’s lead author, Daniel DiGiulio, MD, a research associate and clinical instructor in medicine. “It may be that an event in the first trimester or early second trimester, or even prior to pregnancy, starts the clock ticking.”
The researchers also followed the women's bacterial communities for up to a year after their deliveries and found that all new mothers shifted to the high-risk pattern, regardless of if their babies were born early or on time or if they had a c-section or vaginal delivery. This finding may help explain why women with closely-spaced pregnancies are more likely to have a preterm baby the second time around, however more work is needed to better understand this discovery, concluded researchers.
Ultimately, the research team hopes to use their findings to develop interventions that could prevent preterm birth. That would definitely be good news for moms and babies.
Previously: Counseling parents of the earliest-born preemies: A mom and two physicians talk about the challenges, Stanford/VA study finds link between PTSD and premature birth and Maternal obesity linked to earliest premature births, says Stanford study
Photo by bradleyolin
