Premature Births Behind US Infant Mortality

A new study by the U.S. Centers for Disease Control and Prevention finds that premature births are the main reason the United States lags behind most European countries in infant mortality.

The U.S. currently ranks 30th in the world in terms of infant mortality ““- more than twice the infant mortality rates of Sweden, Japan, Finland, Norway and the Czech Republic.

Roughly 1 in 8 U.S. births are premature, often due to poor care of low-income pregnant women, according to the report.  By contrast, early births occur much less frequently in most of Europe.  In Finland and Ireland, for instance, just 1 in 18 babies are born premature.

Experts blame smoking, maternal obesity, premature cesarean sections and induced labor, poor access to prenatal care and fertility treatments for preterm births.

Babies born before 37 weeks of gestation tend to be more fragile and have under-developed lungs, said the CDC’s Marian MacDorman, lead author of the report.

The U.S. has ranked poorly in infant mortality among industrialized nations for many years. The new CDC study sought to identify the underlying reasons for this discrepancy

If U.S. infants were as mature as Sweden’s babies at birth, nearly 8,000 premature infant births could be avoided, lowering the U.S. infant mortality rate by one-third, according MacDorman and others at the CDC’s National Center for Health Statistics.

Experts offer many possible explanations for the high rates of U.S. infant mortality, including fertility treatments and other types assisted reproduction, which frequently result in multiple births that tend to be delivered early, maternal obesity and smoking, and inducing labor or performing C-sections prior to the 37th week.

March of Dimes medical director Dr. Alan R. Fleischman told the AP that lack of access to prenatal care, particularly for the uninsured, is also a problem.  

Fleischman noted that infant deaths tend to occur in babies who have much shorter than 37 weeks gestation.

In 2006, labor was induced in about 16 percent of premature births, an increase from 8 percent in 1991. Cesarean sections were done in 36 percent of preterm births, up from 25 percent in 1991, MacDorman added.

The CDC report used 2005 data to make comparisons with 14 European countries.  More recent data, such as the International infant mortality statistics for 2006 and 2007, suggest that the U.S. infant mortality rate has remained at about 7 infant deaths for every 1,000 live births since 2000.

However, while the U.S. experienced more premature births, survival rates for infants at that gestational age were equal or better than most European countries.

"So, once the baby is born too early, we do a good job of saving it. What we have trouble with is preventing the preterm birth in the first place," MacDorman said.

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On the Net:

• CDC
• The full CDC report can be viewed at http://www.cdc.gov/nchs/data/databriefs/db23.pdf