More than nine out of 10 Americans, men and women alike, have had premarital sex, according to a new study. The high rates extend even to women born in the 1940s, challenging perceptions that people were more chaste in the past.

"This is reality-check research," said the study's author, Lawrence Finer. "Premarital sex is normal behavior for the vast majority of Americans, and has been for decades."

The study, released Tuesday, appears in the new issue of Public Health Reports.

The study, examining how sexual behavior before marriage has changed over time, was based on interviews conducted with more than 38,000 people. According to Finer's analysis, 99 percent of the respondents had had sex by age 44, and 95 percent had done so before marriage.

The study found women virtually as likely as men to engage in premarital sex, even those born decades ago. Among women born between 1950 and 1978, at least 91 percent had had premarital sex by age 30, while among those born in the 1940s, 88 percent had done so by age 44.

"The data clearly show that the majority of older teens and adults have already had sex before marriage, which calls into question the federal government's funding of abstinence-only-until-marriage programs for 12- to 29-year-olds," Finer said.

Under the Bush administration, such programs have received hundreds of millions of dollars in federal funding.

"It would be more effective," Finer said, "to provide young people with the skills and information they need to be safe once they become sexually active."

Vocabulary:  premarital sex  : 婚前性行为