A U.S. Census Bureau report indicates the birthrate continues to decline.  In 2004, the average number of children that women can expect to have in their lifetime stands at two.

This average compares with three children from the previous generation. In the early 1900s, American women averaged about four children, according to the Census report.

Over one third of women, ages 40-44, polled in 2004 gave birth to two children. The next most common number of children was none, followed by three children.

Population experts attribute the declining U.S. birthrate to varying factors: education, marriage in later life, infertility, divorce, full-time employment, and homosexual relationships.

The U.S. population is expected to reach 300 million by year’s end. A United Nations report estimates the world’s population which now stands at 6.5 billion will reach nine billion by 2050.

A federal survey of U.S. teenagers concludes that the percentage of high school students involved in risky behaviors fell from 51 percent in 1991 to 43 percent in 2005.  The findings were released Thursday by the U.S. Centers for Disease Control.

Nearly 14,000 students from 40 states took part in the 2005 National Youth Risk Behavior Survey involving public and private high schools across the country.  The data is used to assess trends in risky behavior levels for the purpose of shaping school health programs.

The findings show that teens are smoking and drinking less than they were 15 years ago, fewer are sexually active, and the number who rarely or near wear a car safety belt is significantly lower than in 1991.

However, efforts must persist to reduce risky behaviors across racial and ethnic lines, according to CDC officials. For example, white students generally smoke more frequently or engage in heavy drinking; black students are more likely to be sedentary or engage in sexual risk behaviors; Latinos use drugs and attempt suicide at higher rates than their white and black classmates.

About 71 percent of deaths among 10- to 24-year-olds in the U.S. are a result of motor vehicle crashes, unintentional injuries, murder or suicide, according to the study.