Variants in fetus's DNA may trigger some early births

Feb 4 2015

Some babies seem to have a genetic predisposition to a higher risk of being born too soon, according to researchers in a study to be presented on Feb. 5 in an oral concurrent session at 8 a.m. PST, at the Society for Maternal-Fetal Medicine's annual meeting in San Diego. The study titled Neonatal, not Maternal, Copy Number Variants are Associated with Spontaneous Preterm Birth found that variants in the fetus's DNA - not the mother's - may be what triggers some early births.

Joseph R. Biggio, MD, of the University of Alabama, and his colleagues from the Eunice Kennedy Shriver Genomics and Proteomics Network for Preterm Birth Research analyzed the number of copies of certain genes in the blood or saliva from hundreds of babies and their mothers. While there was no link between the number of copies of the mother's genes and the chances of a preterm baby, there was a two- to eleven-fold increase in preterm births before 34 weeks of pregnancy when any of four genes were duplicated or seven genes were deleted in the babies born preterm, when compared to babies born full-term.

"These findings may help explain what triggers early labor in some women even when they've done everything right during pregnancy and there's no obvious cause for an early birth," explained March of Dimes Chief Medical Officer Edward R. B. McCabe, MD, MPH. "The hope is that this finding may one day lead to a screening test to help identify which babies are at a higher risk of an early birth."

The preterm birth rate in the United States dropped more than 10 percent between 2013 and 2006, with most of the improvement focused in late preterm births (those between 34 and 37 weeks of pregnancy). Today's research findings focused on early preterm births, births before 34 weeks of pregnancy, in which there has been little improvement in recent years.

More than 450,000 babies are born too soon each year in the U.S. Preterm birth (birth before 37 weeks of pregnancy) is the leading cause of newborn death, and babies who survive an early birth often face an increased risk of a lifetime of health challenges, such as breathing problems, cerebral palsy, intellectual disabilities and others. Even babies born just a few weeks early have higher rates of hospitalization and illness than full-term infants. It is a serious health problem that costs the United States more than $26 billion annually.

Dr. Biggio's research is being honored by the March of Dimes at the annual Society for Maternal Fetal Medicine. Dr. McCabe presented Dr. Biggio with the March of Dimes award for Best Abstract in Prematurity at the SMFM's Annual Meeting. 2015 marks the 12th year the March of Dimes award has been presented.

While the differences in the number of copies of the genes may not be causing a preterm birth, they may put a baby at a higher risk of infection or reacting to other harmful environmental factors that may trigger early labor and delivery, explained Dr. Biggio.

It may also help explain why treatment with progesterone, a naturally-occurring hormone in pregnancy shown to prevent some preterm births, work for only about one-third of women.

"We always thought we were treating the mother with progesterone, but perhaps we were actually treating the baby," Dr. Biggio said. Dr. Biggio's research was funded by the Eunice Kennedy Shriver National Institute of Child health and Human Development.

Source: Society for Maternal-Fetal Medicine