Expectant mothers who are obese before they become pregnant are at increased risk of delivering a very premature baby, according to a new study of nearly 1,000,000 California births.
The study, which appears in the July issue of Paediatric and Perinatal Epidemiology, is part of a major research effort by the March of Dimes Prematurity Research Center at Stanford University School of Medicine to understand why 450,000 U.S. babies are being born too early each year. Figuring out what causes preterm birth is the first step in understanding how to prevent it, but in many cases, physicians have no idea why a pregnant woman went into labor early.
The new study focused on preterm deliveries of unknown cause, starting from a database of nearly every California birth between January 2007 and December 2009 to examine singleton pregnancies where the mother did not have any illnesses known to be associated with prematurity.
The researchers found a link between mom’s obesity and the earliest premature births, those that happen before 28 weeks, or about six months, of pregnancy. The obesity-prematurity connection was stronger for first-time moms than for women having their second or later child. Maternal obesity was not linked with preterm deliveries that happen between 28 and 37 weeks of the 40-week gestation period.
From our press release about the research:
“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 the lead author of the new research. “But it’s not as simple as that. Preterm birth is not one construct; gestational age matters.”
The researchers plan to investigate which aspects of obesity might trigger very early labor. For example, Shaw said, the inflammatory state seen in the body in obesity might be a factor, though more work is needed to confirm this.
Previously: How Stanford researchers are working to understand the complexities of preterm birth, A look at the world’s smallest preterm babies and New research center aims to understand premature birth
Photo by Evelyn