From 1943 to 1999, the percentage of young women who approved of premarital sex climbed from 12 percent to 73 percent. That compared to the attitudes of young men, which went up from 40 percent to 79 percent.
Young women defined as "sexually active" increased from 13 percent to 47 percent during the same period, and the age for first experiencing sexual intercourse dropped from 19 to 15.
"The change in young women's beliefs about premarital sex was enormous," the study's co-author, Jean Twenge, said yesterday.
Researchers at San Diego State combed through 530 surveys involving 269,649 young people aged 12-27. The participants were evenly divided between regions of the country. About half came from what the school called "ethnically diverse" backgrounds.
The study also found that acceptance of oral sex had shown a strong increase.
Between 1969 and 1993, men engaging in oral sex grew from 48 percent to 72 percent, while women climbed from 42 percent to 71 percent.
"In previous generations, oral sex was considered disgusting," said Twenge, a psychology professor. "Now young people see it as another way of being sexual. It's also part of the general trend of sexual behavior moving away from marriage and reproduction and toward pleasure."
The study was co-authored by Brooke Wells, a former SDSU graduate student now at the City University of New York. It appears in the latest issue of the Review of General Psychology.