Preemie Rates Drop After 25 Year Increase

May 11, 2010— -- After a long period of fairly steady increase, the preterm birth rate in the U.S. has declined for the second straight year, investigators found.

In 2008, the rate was 12.3 percent of all births being premature, down from 12.7 percent in 2007 and 12.8 percent in 2006, Joyce A. Martin, of the U.S. Centers for Disease Control, and colleagues reported in a statistical brief.

"It's a very encouraging decline, and we're hopeful that it portends the beginning of a long-term downward trend, but it's too early to tell if that's the case," Martin told MedPage Today.

The new numbers mark the first two-year decline in nearly three decades, Martin said.

Between 1980 and 2006, rates of premature births rose by more than a third.

The researchers speculated that the increase may have been driven by greater use of interventions such as inducing labor and cesarean delivery earlier in pregnancy.

More recently, they wrote, obstetricians may be putting a halt on early use of those procedures.

"I think it is very likely that this decrease relates to the widely publicized criticism of delivering babies 'early' for a laundry list of poorly-defended indications," Dr. Ian Holzman, chief of newborn medicine at Mount Sinai Medical School in New York City, said in an e-mail.

"We are finally not scheduling inductions for convenience at less than 39 weeks," he said. "Similarly, cesarean sections don't occur early unless there is a strong medical indication."

Holzman, who was not involved in the study, added that there's likely also better control of multiple gestations via reproductive technology, as multiples have higher preterm rates than singletons.

But Martin noted that declines in preterm birth occurred across all categories, even among non-induced births.

"Fewer interventions might be influencing the decline, but the fact that it occurred among non-induced births is very interesting," she said. "It's a very complex puzzle."