The nearly 1.5 million unwed births amounted to about 36 percent of all births in the country. And those moms were more likely to be 20-somethings than teenagers, according to the new federal data.
Last year, teens accounted for just 24 percent of the unwed births -- down from 50 percent in 1970. The report was compiled by the National Center for Health Statistics.
Births last year to both married and unwed mothers totaled more than 4 million, up from 2003. The government said increases in unmarried births have been among women in their 20s, particularly those 25 to 29.
Researchers found many women in that age group are living with partners but still count as unmarried mothers if they haven't formally married.
The report also finds that births to older women continued to increase. The birth rate for women ages 35 to 39 increased 4 percent from 2003 to 2004. It rose 3 percent for women ages 40 to 44 and 9 percent for those 45 to 49.
