Researchers at the University of California, San Francisco found that girls are "at particular risk for experiencing negative social and emotional consequences of having any type of sex," including oral sex. According to Healy, "Early sex is a threat, and it remains a greater threat to girls than to boys." "Just because a girl has matured physically, doesn’t mean she’s socially or psychologically mature."
The American Psychological Association task force in 2007 found that an early emphasis on sexuality stunts girls' development in other areas. "When kids are about defining themselves, if you give them this idea that sexy is the be-all and end-all, they drop other things," says Sharon Maxwell, a psychologist who specializes in adolescent sexuality.
Casual sex
Benoit Denizet-Lewis, a fellow at the Alicia Patterson Foundation, found in his study of casual sex among adolescents that many girls believe they can have a purely sexual experience with no emotional ties, and they believed it was sexist to assume otherwise. However, he believes that both the girls and the boys who were hooking up often really were depressed and didn't feel very good about themselves.
In his research, Denizet-Lewis found that "all the experts who talk about teen sexuality maintain that... it's impossible" for girls to enjoy meaningless sex as much as boys. Girls will "inevitably regret what they did." Speaking on National Public Radio, Lukas noted that girls "particularly are suffering from the new regime [i.e. casual sex] and are having some lasting problems" as a result of it.
On the other hand, a 2009 study of college-age young adults by Marla Eisenberg and colleagues did not find any significant differences in terms of harmful psychological outcomes between those who engaged in casual sex and those who were in more committed relationships, and also found no significant gender differences in such effects.
Emotional effects
While teens may believe that their sexual activities are fine at the time, Lukas cautions that they may feel very differently in time and may regret the choices they made. She points to research that shows 2/3 of sexually active girls wish they had waited longer before having sex. Sex therapists have found that the roots of sexual issues facing adults often date back to regretful teenage experiences. Of seniors in high school, 74% of girls regret sexual experiences they have had.
Girls are more than twice as likely as boys to say they felt bad about themselves and more than three times as likely to say they felt used as a result of engaging in sex. For girls, even modest involvement in sexual experimentation elevates depression risk. Sexually active teenage girls are more than twice as likely to suffer depression compared to those who are not sexually active.
Research has also found that adolescent sexual abstinence was associated with better mental health at age 29, and that girls who were virgins at age 18 were less likely to have a mental illness at age 40.
Dating violence
Girls who have engaged in sexual intercourse are five times more likely than their virgin peers to be the victim of dating violence. Girls who were intentionally hurt by a date in the past 12 months are at a "significantly elevated risk for a broad range of sexual health concerns and for pregnancy." Girls who have been victims are also twice as likely to report high levels of multiple sexual partners.