WASHINGTON (Reuters) - Worried parents seeking to preserve their daughters' innocence should encourage them to join in sports, researchers said. The study found that teen-age girl athletes were less likely to get pregnant, had fewer sexual partners, postponed sex until later and were more likely to use contraceptives once they did have sex. The Women's Sports Foundation, which analyzed data from two surveys involving more than 11,000 students in grades 9 through 12 for its report, recommended that sports be made more available to teen-age girls. "Female athletes in the nationwide survey were less than half as likely to get pregnant as female non-athletes," the report said. Five percent of athletes, compared to 11 percent of girls who did not take part in sports, got pregnant. "Female athletes were more likely to be virgins," it added. "We contend that sports are a cultural resource that builds girls' confidence, sense of physical empowerment, and social recognition within the school and community," the report concluded. "Girls may be using the self-reliance and social status gained through athletic participation to resist social pressures to exchange sex for approval or popularity. The survey also checked the effects of sports on boys and found that, if anything, male athletes were more likely to have sex.