Study Quantifies Risk Factors for Preterm Birth

CINCINNATI -- A significant portion of preterm births might be avoided by reducing or eliminating three major risk factors.

A new Cincinnati Children's Hospital Medical Center study shows that as many as 25 percent of preterm births might be attributed to abnormalities in the interval between pregnancies, the mother's body mass index prior to pregnancy, and the amount of weight gain in pregnancy. All of these risk factors may be modifiable to reduce the risk of premature births - those before 37 weeks of gestation.

The study is published online in the Maternal and Child Health Journal.

"The highest risks for premature birth were in women who were underweight, had poor weight gain during pregnancy, or short periods of time between pregnancies," says Emily DeFranco, DO, a physician-researcher at the Center for Prevention of Preterm Birth at Cincinnati Children's and an associate professor of maternal-fetal medicine at the University of Cincinnati College of Medicine. "However, excessive weight gain in obese women also increased the risk."

DeFranco and her colleagues conducted the study from birth records in Ohio from 2006 to 2011. Nearly 400,000 live, non-multiple births were included. Potentially modifiable risk factors for preterm birth were present in more than 90 percent of women in the study. Fewer than half of women begin pregnancy with a normal weight, and only 32 percent achieve the recommended pregnancy weight gain.

"Attention should be paid to educational interventions on the importance of birth spacing, achieving an optimal pre-pregnancy weight, and ensuring adequate nutrition and weight gain during pregnancy," says DeFranco. "Improvements in these modifiable risk factors could have significant influence on premature birth and infant mortality worldwide."

According to the March of Dimes, the rate of preterm birth in the United States is 12 percent. This is above the global average of 11.1 percent.

The research was funded in part by the March of Dimes.