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Microbiome may help predict risk for preterm birth

The unique microbiome in the female reproductive tract may eventually be used to predict a woman’s probability of giving birth prematurely, according to a presentation at the NIH’s workshop, “The Human Microbiome: Emerging Themes at the Horizon of the 21st Century.”

“The microbiome of the female reproductive tract is thought to have a major impact on women’s reproductive health and well-being, including but not limited to health during pregnancy and its adverse outcomes including preterm birth and still birth,” Gregory A. Buck, PhD, from the department of microbiology and immunology at the Virginia Commonwealth University, wrote in the abstract. “Bacterial vaginosis, with its still poorly defined etiology, has a point prevalence of up to 30%, and carries a higher risk for adverse pregnancy outcomes.”

During the presentation, Buck underscored the prevalence and adverse risks of preterm birth, stating that approximately one in ten births are preterm (prior to 37 weeks gestation) and more than 12 million preterm births occur each year.

“The mortality rate is as high as 40% and survivors have short- and long-term health issues,” he said. “In addition, more than $26 billion is spent in the United States each year for prematurity associated health care.”

“Thirty to 40% of preterm births are caused by poorly defined bacterial agents,” he added. “We know that complex vaginal microbiomes have negative risks for preterm births.”

Buck and colleagues conducted the Multi Omic Microbiome Study: Pregnancy Initiative (MOMS PI) to determine the mechanisms by which the microbiome of the female reproductive tract affects pregnancy outcomes, specifically preterm birth, using longitudinal multi omic strategies. They collected nearly a quarter million comprehensive samples from 1,594 mothers and offspring over 3.5 years. For pregnant women, cervical, vaginal, buccal, rectal and skin swabs, and blood, plasma and urine samples were collected. For neonates, placenta, cord and cord blood taken at birth, and buccal, meconium, skin and first stool samples were collected. Premature delivery occurred in approximately 10% of participants.

The researchers used taxonomic, metagenomic, metatranscriptomic and cytokine profiling to select panels of samples from participants who gave birth prematurely or at term. The preliminary data confirmed that during pregnancy there is a uniquely complex microbiome in the female reproductive tract that is altered and influenced by environmental and clinical factors. This alteration demonstrates racial biases that are seen in preterm births. Buck stated that blacks have a significantly higher rate of adverse outcomes during pregnancy, including preterm births. Multi omic analyses revealed associations between multi omic profiles and clinical observations and suggest that strain differences may impact pregnancy outcomes.

“The results are altering the traditional view of women’s vaginal and reproductive health and promise earlier prediction of adverse reproductive events,” Buck said.

Eventually, multi omic data may have clinical implications to predict preterm risk during pregnancy, he said.

Buck emphasized that there are critical gaps and clear racial differences that are influenced by both genetics and environmental factors. He indicated a need to look more into the human genome and epigenomics to determine the reason for these gaps. – by Alaina Tedesco

Disclosure: Buck reports receiving grants from the NIH Common Fund Human Microbiome Project program.