Trillions of unique tiny cells called microbes harbored in the reproductive tract of pregnant women could hold the key to predicting preterm births.
Microbes cover every surface of our body, inside and out, and are unique to us – much like fingerprints. Results from a study published in the journal Proceedings of the National Academy of Sciences reveal microbiomes – a community of microbes – are significantly different for woman who give birth prematurely.
When a baby is born alive before 37 weeks of pregnancy are completed, it is defined as a preterm birth. According to the World Health Organization (WHO), an estimated 15 million preterm babies are born every year around the world, and the number continues to rise.
Preterm birth complications are currently the worldwide leading cause of death among children under 5 years old.
Those who survive may also suffer complications later in life. Medical News Today recently reported how preterm infants may be at greater risk of neurodevelopmental disorders, flu-related illnesses and introversion in adulthood.
Although more than 60% of preterm births occur in Africa and South Asia, the issue is a global one. In the US, more than 450,000 babies are born too soon every year, with the country ranked sixth in the top 10 countries with the greatest number of preterm births.
Early births have been known to occur without any possible cause identified. However, both the Centers for Disease Control and Prevention (CDC) and the WHO have warned of a number of factors that can be an influence.
Possible causes include multiple pregnancies, infections and chronic conditions such as high blood pressure and diabetes. Behavioral factors such as substance abuse, stress, tobacco and alcohol use have also been linked to preterm births.
Researchers at the March of Dimes Prematurity Research Center at Stanford University, CA, sought to investigate the issue. Senior author Prof. David Relman, from the Stanford University School of Medicine, explains:
“We wanted to develop a baseline understanding of what happens to the human microbiome during pregnancy, both in women who deliver healthy, term babies and in those who deliver prematurely.”
Scientists analyzed 49 pregnant women, of whom 15 went on to deliver prematurely. Weekly samples of microbes were taken from the women’s stool, saliva, reproductive tract and teeth and gums for research.
They discovered that women in the study with a lower level of the vaginal bacteria Lactobacillus had an increased risk of delivering their baby preterm. Lactobacillus is thought to be beneficial to health because it produces vitamin K and amino acids.
Researchers also discovered low levels of Lactobacillus, in conjunction with higher levels of the bacteria Gardnerella and Ureaplasma, further increased the risk of preterm births. This fact was validated when vaginal samples were taken from nine women, in which four went on to have preterm births.
Prof. Relman believes the results may better help us predict preterm births.
“These findings may help us screen women and identify and predict those who are more likely to have a baby born too soon,” he says.
The study’s lead author Dr. Daniel DiGiulio believes this research indicates the pivotal role of microbiomes:
“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. It may be that an event in the first trimester or early second trimester, or even prior to pregnancy, starts the clock ticking.”
Researchers also discovered women’s microbiome patterns changed immediately to a high-risk pattern after giving birth, regardless if their baby was born preterm. This revelation was described as a “surprise” by Prof. Relman, but he said this may explain why women with closely spaced pregnancies are often at risk of preterm birth.