A new study of premature birth rates around the world finds that early deliveries are common in the United States -- caused by a combination of factors ranging from high obesity rates to fertility treatments that result in multiple births.
Countries with the greatest number of pre-term births were in the developing world, where malnutrition, poor access to prentatal care and lack of family planning contribute to the high numbers, according to the World Health Organization report.
But compared to other developed countries, rates of premature births in the United States were high. The average rate for high-income countries was just over nine percent. Nearly 12 percent of U.S. babies are born too soon, the report says.
For U.S. births, the report pointed to different factors, including births to older mothers, increased rates of multiple births associated with assisted reproduction, and population risk factors, including diabetes, obesity and high blood pressure.