Women who are obese before they become pregnant face an increased risk of delivering a very premature baby, according to a new study of nearly 1 million California births.
The findings from the Stanford University School of Medicine provide important clues as to what triggers extremely preterm births, specifically those that occur prior to 28 weeks of pregnancy.
The study, published in the July issue of Paediatric and Perinatal Epidemiology, found no link between maternal obesity and premature births that happen between 28 and 37 weeks of the normal 40-week gestation period. The disparity suggests that premature birth may have different causes at different stages of pregnancy.
"Until now, people have been thinking about preterm birth as one condition, simply by defining it as any birth that happens at least three weeks early," said Gary Shaw, DrPH, professor of pediatrics and lead author of the new study. "But it's not as simple as that. Preterm birth is not one construct; gestational age matters."
Preterm births affect one in nine pregnancies, or more than a half-million U.S. babies per year. Prematurity can lead to lifelong health problems, such as cerebral palsy, developmental delays and impaired vision or hearing. Babies born before 28 weeks of pregnancy are at especially high risk.
High U.S. prematurity rates prompted the 2011 launch of the March of Dimes Prematurity Research Center at Stanford University School of Medicine, the first of five such centers the March of Dimes has planned across the country. The new findings are a product of the center's work.
The study, which examined nearly all California births between January 2007 and December 2009, was the largest ever to look for population-based links between maternal obesity and prematurity. To focus on spontaneous preterm births, the researchers excluded from analysis women who were pregnant with twins or other multiples, as well as wo
|Contact: Erin Digitale|
Stanford University Medical Center