Babies' Genes May Hold Clues To Preterm Birth
Much of the existing research on babies who are born preterm, or before 37 weeks of pregnancy, has focused on their mothers, investigating what causes some women to deliver early.
But that conversation could soon begin to shift, based on a preliminary new piece of research suggesting that a fetus' DNA -- not a mother's -- may contribute to at least some premature births.
The findings will be presented this week at the annual Society for Maternal-Fetal Medicine meeting. The study compared the DNA of some 900 babies born before 34 weeks and their mothers with a comparably-sized control group of babies born full-term and their mothers. (Though a premature baby is technically defined as one born before the 37th week of pregnancy, the researchers used a baseline of 34 weeks. Generally speaking, the earlier a baby is born, the greater his or her risk of serious problems, including death.)
Using blood and saliva samples, the study's researchers, led by Dr. Joseph Biggio, director of the University of Alabama at Birmingham's Division of Maternal-Fetal Medicine, looked for copy number variations, or areas where the DNA had duplications or deletions.
In the women's genes, the researchers found no clear link between copy number variations and increased risk of preterm birth. However, there was a twofold to elevenfold increase in preterm birth among infants who had any four gene duplications or seven gene deletions.
"The fact that we identified areas where there was a fetal predisposition [to being born before 34 weeks] tells us that preterm labor is not just a maternal problem ... that there is something inherent to the fetus that could contribute to this," Biggio told The Huffington Post. "We have to begin to think outside the box and say, 'Okay, what can we address there?' Maybe many of the treatments we've tried haven't worked because we're trying to stop maternal processes, whereas this really started far earlier, with the fetus."
Preterm birth can lead to a host of short- and long-term health issues for babies, and has been estimated to cost the U.S. health care system more than $26 billion annually.
In 2013, the national preterm birth rate dropped to a 17-year low, according to a report issued by the March of Dimes, a nonprofit that works to curb premature birth. But the organization -- which also awarded Biggio's research "Best Abstract in Prematurity" at the SMFM meeting this week -- gave the U.S. a "C" on its annual report card, pointing out that the nation still has among the highest rates of preterm birth of any high-resource country.
Part of the reason that premature birth remains a major public health issue is that doctors and researchers do not fully understand its many causes. In an email to HuffPost, Dr. Edward McCabe, chief medical officer for the March of Dimes, said the new findings represent a novel way of approaching that question. To date, he noted, research has focused largely on women, looking at modifiable behaviors and internal biomarkers that may be linked with increased risk.
"This research opens a new line of thinking about preterm birth -- it shifts the paradigm," McCabe said. "There is nothing that can be done at this moment to prevent [it], but it indicates that we cannot investigate the mother in isolation from the baby in her womb. The baby's genetic makeup may have a physiologic cross-talk with the mother that results in preterm birth."
Yet Biggio himself was careful to emphasize that his team's findings are preliminary, estimating that it may be at least 10 years before they have any real-world applicability. It is not yet known what these particular duplications or deletions do to the function of a baby's genes, he said, or how this might contribute to the problem of preterm birth. Nor are researchers able to estimate how many fetuses carry these genetic variations.
"But," Biggio said, "it gives us some place new to look, and gives us a little more hope that we may be able to identify something we can treat."