Division of Vital Statistics, Centers for Disease Control and Prevention, National Center for Health Statistics, Hyattsville, MD 20782, USA.
Pediatrics. 2012 Feb;129(2):338-48. doi: 10.1542/peds.2011-3435. Epub 2012 Jan 30.
The number of births in the United States decreased by 3% between 2008 and 2009 to 4 130 665 births. The general fertility rate also declined 3% to 66.7 per 1000 women. The teenage birth rate fell 6% to 39.1 per 1000. Birth rates also declined for women 20 to 39 years and for all 5-year groups, but the rate for women 40 to 44 years continued to rise. The percentage of all births to unmarried women increased to 41.0% in 2009, up from 40.6% in 2008. In 2009, 32.9% of all births occurred by cesarean delivery, continuing its rise. The 2009 preterm birth rate declined for the third year in a row to 12.18%. The low-birth-weight rate was unchanged in 2009 at 8.16%. Both twin and triplet and higher order birth rates increased. The infant mortality rate was 6.42 infant deaths per 1000 live births in 2009. The rate is significantly lower than the rate of 6.61 in 2008. Linked birth and infant death data from 2007 showed that non-Hispanic black infants continued to have much higher mortality rates than non-Hispanic white and Hispanic infants. Life expectancy at birth was 78.2 years in 2009. Crude death rates for children and adolescents aged 1 to 19 years decreased by 6.5% between 2008 and 2009. Unintentional injuries and homicide, the first and second leading causes of death jointly accounted for 48.6% of all deaths to children and adolescents in 2009.
2008 年至 2009 年，美国的出生人数减少了 3%，降至 4130665 人。总生育率也下降了 3%，降至每 1000 名女性 66.7 人。青少年出生率下降了 6%，降至每 1000 名女性 39.1 人。20 至 39 岁的女性和所有 5 岁年龄组的出生率也有所下降，但 40 至 44 岁的女性出生率继续上升。2009 年，未婚女性所生孩子的比例上升至 41.0%，高于 2008 年的 40.6%。2009 年，所有分娩中有 32.9%是通过剖腹产进行的，这一比例继续上升。早产儿的比例连续第三年下降，至 12.18%。2009 年，低出生体重率保持不变，为 8.16%。双胞胎、三胞胎和更高胎次的出生率都有所增加。2009 年婴儿死亡率为每 1000 例活产婴儿 6.42 例。这一比例明显低于 2008 年的 6.61。2007 年的活产婴儿和婴儿死亡关联数据显示，非西班牙裔黑人婴儿的死亡率仍然明显高于非西班牙裔白人和西班牙裔婴儿。2009 年出生时的预期寿命为 78.2 岁。2008 年至 2009 年，1 至 19 岁儿童和青少年的粗死亡率下降了 6.5%。2009 年，意外伤害和凶杀是儿童和青少年死亡的前两个主要原因，共占所有死亡人数的 48.6%。
