Researchers have found genetic mutations that affect whether a woman is likely to have her baby early or carry it to full term.
Even late preterm babies, those born between 34 and 36 weeks of gestation, are more likely to die or experience problems, even if they are the size and weight of some full-term infants born after 37 to 41 weeks in the womb.
Preterm birth is the leading cause of death among children younger than 5 worldwide. These babies have higher death rates even into adolescence and beyond.
Several studies show health problems related to preterm birth persist through adult life, problems such as chronic lung disease, developmental handicaps, vision and hearing losses. The World Health Organization reports that every year, an estimated 15 million babies are born early, and this number is rising. Until now, little was known about the causes, but these findings could help solve the mystery.
Beginning of a journey
Dr. Louis Muglia coordinated the study of the DNA of more than 50,000 pregnant women. The study identified six gene regions, which influence the length of pregnancy and the timing of birth. While the study doesn’t provide information about how to prevent prematurity, Muglia says it could eventually do that.
“It’s just the beginning of the journey, but at least we know now, what the foundation is,” he says.
Muglia is co-director of the Perinatal Institute, which focuses on preterm babies, at Cincinnati Children’s Hospital Medical Center. He’s also the principal investigator of one of the March of Dimes’ five prematurity research centers. The March of Dimes helped pay for the study along with the National Institutes of Health, the Bill and Melinda Gates Foundation and other medical research institutes.
Muglia said scientists have known for a long time that preterm birth is a combination of genetic and environmental factors. This study showed the genes involved were from the mother.
“For the first time, we have an idea of what tissue in the mom is the one that is likely driving the one for preterm birth,” Muglia says.
One of the genes identified is involved in how the body uses selenium, a common mineral provided in food or supplements, but not currently included in vitamins women commonly take while pregnant. Selenium supplements are low-cost, and if the results are confirmed, this supplement could save millions of lives. Supplements including folic acid have been shown to greatly reduce birth defects, so much so that food in many countries is fortified with this particular B vitamin.
Another gene indicated that cells that line the uterus play a larger-than-expected role in the length of pregnancy.
The researchers were from the U.S. and from Norway, Denmark, Finland and Sweden. They only tested women of European descent, so more work needs to be done involving women of other races and ethnic origins.
But their study does open up areas for researching potential diagnostic tests, new medications, improved dietary supplements or other changes that could help more women have full-term pregnancies, all areas which will require several more years of study.
The study was published in the New England Journal of Medicine.