The chance of a baby in the United States dying before its first birthday continues to get worse compared to that risk in other countries, new statistics show.

The U.S. now ranks 29th in the world for infant mortality, compared to its previous ranking of 27th eight years ago, according to a report released today by the Centers for Disease Control (CDC). Back in 1960, the country stood at No. 12 for those deaths.

The new ranking is based on infant deaths in 2004, the most recent year data was available for 37 developed countries. Singapore ranked first, with 2 infant deaths per 1,000 live births; Romania was last, with 16.8 infant deaths per 1,000 births.

The actual rate of U.S. infant deaths in 2005 — 6.86 per 1,000 live births — was pretty much the same as it was in 2000, when it was 6.89 per 1,000. But for the first time since the 1950s, the rate has plateaued, just as the government is pushing to lower it to 4.5 infant deaths per 1,000 births by 2010.

Why? Epidemiologists blame a growth in preterm births, or deliveries before 37 weeks gestation, when life-threatening complications are more likely. A full-term birth occurs between 37 and 41 weeks of pregnancy.

Some of the increase in early deliveries is due to more multiple births, a phenomenon tied to use of assisted reproductive technologies. Elective cesarean sections also play a role, says Marian MacDorman, a senior statistician at the National Center for Health Statistics.

As preterm births rose from nearly 12 percent to almost 13 percent between 2000 and 2005, so did preterm-related infant deaths, climbing by 5 percent to 37 percent of cases. The increase in those early births came from "medically indicated" deliveries — c-sections or induced labor ordered by doctors, MacDorman says.

"Of course, c-sections are very critical in some cases to save the life of the mother and the baby," MacDorman says. But, "There's increased talk about medically elective c-sections, which can affect infant health in a lot of ways: They're performed earlier, sometimes before the woman is in labor, and if they're performed early enough, it's preterm, when the risk of death is higher."

The U.S. c-section rate is around 30 percent — double the World Health Organization's recommendation.

Epidemiologists consider infant mortality a kind of marker of a nation's overall health, as it's linked to mothers' health, quality and access to medical care, socioeconomic conditions, and public health practices. A preliminary estimate shows that the U.S. infant mortality rate fell in 2006 to 6.71 per 1,000 births.

(Image by iStockphoto/Jenny Bonner)