FRIDAY, July 9 (HealthDay News) -- In an annual report gauging the health and well-being of America's children, a group of 22 federal agencies reports progress in some areas, preterm births and teen pregnancies in particular, but bad news in other areas, like the number of teens living in poverty.

"This report is a status update on how our nation's children are faring, and it represents large segments of the population," Dr. Alan E. Guttmacher, acting director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, said during a press conference.

The report, titled America's Children In Brief: Key Indicators of Well-Being, 2010, was released July 9.

According to the report, in 2009 there were 74.5 million people under 18 years of age living in the United States. That number is up 2 million since 2000.

Seventy percent of those children lived in households with two parents, while 26 percent lived with just one parent. Four percent of the nation's children live without either parent.

One of the most positive findings from the study was a drop in the rate of preterm births.

"There was a decline in the number of preterm births, and the decline was seen in each of the three largest racial and ethnic groups," said Edward Sondik, director of the Centers for Disease Control and Prevention's National Center for Health Statistics, during the press conference.

The preterm birth rate -- babies born before 37 weeks of gestation -- dropped from 12.7 percent in 2007 to 12.3 percent in 2008. This is the second straight decline after years of steadily increasing rates of preterm birth, according to the report.

According to Sondik, "the etiology of preterm birth is quite complex and it's hard to know for sure which factors are responsible for this dip."

Dr. Diane Ashton, deputy medical director for the March of Dimes, said some research suggests that a reduction in the number of elective Cesarean births done before 39 weeks of gestation may be at least part of the reason that preterm birth rates are going down.

"We're pleased that we're seeing a turn in preterm birth rates, and hope the trend continues," said Ashton. She recommended that women hoping to avoid preterm birth seek good preconception care and have regular medical care throughout pregnancy. In addition, she said, folic acid can help to prevent birth defects and may reduce the risk of preterm birth.

The report also found that the rate of teens giving birth has declined. In 2008, teens between 15 and 17 years old gave birth at a rate of 21.7 per 1,000 girls. In 2007, that number was 22.2 per 1,000, according to the report.

Other good news in the report included slight gains in test scores in reading and math for eighth graders, more kids completing high school and going to college, more children covered by health insurance, fewer children having untreated dental cavities and fewer children being exposed to secondhand smoke.

But, the news wasn't all good for the nation's youngsters.

"These data clearly show that the economy is affecting children," said Sondik.

In 2008, 22 percent of America's children lived in homes dubbed "food insecure," which means that there isn't always access to enough food in the home. That number was up from 17 percent in 2007.

Not surprisingly, the number of children living in homes where at least one parent was working full-time also decreased by 2 percent, and the number of children living in poverty rose from 18 percent to 19 percent from 2007 to 2008, according to the report.

"It's good that this snapshot of America's children shows that most indicators are positive," said Dr. Kenneth Bromberg, chairman of pediatrics at the Brooklyn Hospital Center in New York City. "It looks like child health right now is stable, but given what we know about the economy, I worry we'll have challenges in the next year or two."

More information

To read the full report, visit the Federal Interagency Forum on Child and Family Statistics.