About 18 percent (1.9 million) of American women ages 40-44 were childless in 2008, a 10 percent increase from 1976, according to a study by the Pew Research Center.
The independent group's analysis of census data found that about 20 percent of white women are childless, compared with 17 percent of Hispanics and blacks, and 16 percent of Asians, the Associated Press reported.
Since 1994, rates of childlessness among Hispanics and blacks has increased by 30 percent, about three times the rate for whites, according to the study.
"Social pressure to bear children appears to have diminished for women and that today, the decision to have a child is seen as an individual choice," according to study authors Gretchen Livingston and D'Vera Cohn, the AP reported. "Improved opportunities and contraceptive methods help create alternatives for women," they added.