(ABC NEWS) -- Americans had fewer babies in 2011 than in any year before, according to an annual summary of vital statistics.
In 2011, 3,953,593 babies were born in the U.S. -- 1 percent fewer than in 2010 and 4 percent fewer than in 2009, according to Brady Hamilton, PhD, of the CDC in Atlanta, and colleagues at the agency and the Johns Hopkins Bloomberg School of Public Health in Baltimore.
That number, combined with population data, yielded a crude birth rate of 12.7 per 1,000 people, the lowest rate ever reported for the nation, they reported online and in the March 2013 issue of Pediatrics.
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The general fertility rate -- defined as the number of births per 1,000 women ages 15 through 44 -- also fell by 1 percent, to a record low of 63.2 in 2011, down from 64.1 in 2010.
But the declines were not uniform according to age, the authors pointed out.
The birth rate among all teenagers (ages 15-19) fell by 8 percent from 2010 to 2011, reaching a historic low of 31.3 births per 1,000 women. That rate has been falling for years, Hamilton and colleagues noted and is down 49 percent from 1991, the most recent peak.
The birth rate for teens 15 through 17 fell 11 percent, to 15.4 per 1,000 in 2011, while the rate for 18- and 19-year-olds was down 7 percent, to 54.1 per 1,000.
Rates also fell for women in their 20s, but rose for women 35 through 39 and 40 through 44 years, Hamilton and colleagues found. Rates for women 45 through 49 were unchanged.
The authors also found that the rate of cesarean delivery was unchanged in 2011 at 32.8%, after increasing from 1996 to 2009.
Also, the rate of preterm birth – infants delivered at less than 37 weeks of gestation per 100 births -- was 11.72 percent, down from 11.99 percent in 2010. The decline is the fifth straight, but still leaves the rate higher than the in the 1980s and most of the 1990s.
The rate of low birth weight, defined as less than 2,500 grams, was 8.10 percent in 2011, slightly down from 8.15 percent in 2010.
Finally, preliminary data showed 23,910 infant deaths in the U.S., for an infant mortality rate of 6.05 deaths per 1,000 live births.
The analysis also looked at the other end of the lifespan, reporting 2,513,171 deaths overall in the U.S. in 2011, which was 44,736 more than a year earlier.
But when adjusted for age, the death rate in 2011 was 7.4 deaths per 1,000 U.S. standard population, down 1.3 percent from 7.5 in 2010, the researchers found.
All told, 20,192 children and adolescents died in 2011, yielding a death rate for children, ages 1 through 19, of 25.6 per 100,000 population that was not significantly different from 25.8 in 2010.
The leading cause of death in 2011 for children and adolescents was accidents, at 35.6 percent of all deaths, down significantly from 37 percent in 2010, while the second leading cause was homicide, accounting for 11.4 percent of deaths in 2011, again down significantly from 12.1 percent in 2010.
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