“What we would like to do is identify in a broad way the factors that increase the incidence of premature delivery,” Muglia said. “We want to identify families and examine them for polymorphisms,” genetic differences associated with an increased incidence of premature childbirth.
Muglia and his colleagues have been working with 75 families in the St. Louis area for the past three years, and have started a study of similar families in Finland. “We don’t have data yet,” he said. “It would take many subjects to pick out those genes.”
One working hypothesis is that there might be some hidden evolutionary benefit to preterm delivery. “For maternal survival, it might be better to deliver early,” Muglia theorized.
To support that notion he cited sickle cell anemia, a genetic condition more common in blacks than whites. Carriers of two genes for the condition are at a handicap, but it has been found that the presence of a single sickle cell gene protects the carrier against malaria, Muglia noted.
“I’m not sure it really gives us definitive answers,” said Dr. Diane Ashton, deputy medical director of the March of Dimes. “But it is one aspect that the March of Dimes is looking at to assess the differences in premature births.”
There have been hints of a genetic factor, Ashton added, citing a study indicating that black women were more susceptible to early rupture of the membranes.
“There is some evidence here, but this is one study, and until we have some reproducible results I don’t think we can base our final opinion on just one study,” she said.
A 2006 report by the U.S. Institute of Medicine found that 12.5 percent of American babies were born at least three weeks ahead of their full-term delivery date. Care for those babies costs the nation $26 billion a year, with some requiring neonatal intensive care for two weeks.
Potential problems for premature babies include hearing loss, vision loss, cerebral palsy and seizures. Such problems are most common in babies born before 32 weeks of pregnancy.