The birth rate for U.S. teenagers continues to decline, reaching a historical low in 2010, according to a new report from the Centers for Disease Control and Prevention.

In that year, there were 34.3 births per 1,000 women ages 15 to 19 — the lowest reported since record-keeping began in the 1940s, the report says.

This 2010 birth rate is 9 percent lower than the 2009 rate; and 44 percent lower than the 1991, when a spike in teen births occurred. It's 64 percent lower than the all-time high of 96.3 births per 1,000 teens ages 15 to 19, which occurred in the baby-boom year of 1957.

If the 1991 teen birth rate had not declined, there would have been an estimated 3.4 million additional births to teens between 1992 and 2010, the report says.

The highest birth rate in 2010 was in Mississippi, at 55.0 births per 1,000 teenage women, and the lowest was in New Hampshire, at 15.7 births per 1,000 teenage women, the report says. Since 2007, teen birth rates declined in all states in 2010 except Montana, North Dakota, and West Virginia.

Rates tended to be highest in the South and Southwest, and lowest in the Northeast and Upper Midwest, a pattern that has persisted for many years, the report says.

Rates also fell across all teenage ethnic groups, according to the report.

Strong pregnancy prevention messages directed at teenagers have been credited for the decline, the CDC says. Recent survey data have shown teens are increasingly using contraception when they first have sex, and are using dual contraception methods, such as condoms and hormonal methods, when they are sexually active.

Childbearing by teenagers is a matter of public health concern because of the elevated health risks for teen mothers and their infants. In addition, teenage births costs an estimated $10.9 billion annually, the report says.

The 2010 birth rate estimates are based on preliminary data from the CDC's National Vital Statistics System, which includes information on all births in the United States.

Pass it on: The U.S. teen birth rate in 2010 was the lowest reported in seven decades.

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