Premature birth is a leading cause of death among newborn babies in India and around the world. The majority of death among children occur among neonates, that is, children within the first 28 days of their lives. While countries like India, Brazil and Nigeria have a preterm birth rate of about 12%, the rate is high even in the United States at close to 10%.

While the exact causes of premature delivery remain unknown, there are several risk factors like genetic predisposition, maternal habits like smoking and alcohol consumption and infections of the uterus and urinary tract. Different studies now show that the kinds of microorganisms present in a pregnant woman’s vagina can actually indicate whether she is at higher risk of having a premature delivery.

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A research team at the bio-sciences division of Tata Consultancy Services Research recently published their analysis of 1,621 vaginal microbiome samples from four studies that had been previously conducted. These samples were of women from India, China and the United States. The researchers then mapped the diversity of the microbiomes and the week of pregnancy during which the samples were collected to the outcome of each pregnancy – whether delivery was at term or before term.

They found that women with preterm delivery outcomes tended to have less diversity in their vaginal microbiome during the first 15–20 weeks of pregnancy as compared to women with term delivery outcomes. After about 20 weeks of pregnancy, the vaginal microbiome diversity in both groups appear to converge and remain stable.

Another recent smaller study from the Washington University School of Medicine in the US of predominantly African American women also showed an association of between lower diversity of vaginal microbes of pregnant women and preterm birth. The team studied 77 pregnant women, 24 of whom delivered at least three weeks early. The researchers found that women whose pregnancies went to full term maintained a stable amount and diversity of vaginal microbes, while pregnant women who delivered their babies early experienced decreases in the amount and diversity of such microbes between the first and second trimesters.

The studies show that the vaginal microbiome diversity can be used as predictive tool for the risk of preterm birth and therefore help direct antenatal care, physical or pharmacological interventions and monitoring of women at risk. This could help cut down the risk of preterm birth or have suitable care for a prematurely born baby to ensure its survival.