Apparently, losing their virginity is high on the list for those with significant others, according to researchers who reviewed data from a federal health survey.
While June is the most common month for teens to have sex for the first time - be it in a casual summer fling or steady relationship - sociologists from Mississippi State University say many teens who are dating seriously choose December as the time to have sex for the first time.
In fact, their findings have led them to predict that teens with romantic partners are nearly three times more likely to make their sexual debut in December than those dating casually.
The accent on romance has led them to conclude that the holiday season - and all the mushiness that surrounds it - plays a key role.
"We call it the 'Santa Claus effect,"' says Martin Levin, lead author of the study, which is published in the current issue of the Journal of Marriage and Family.
The data was drawn from the ongoing National Longitudinal Study of Adolescent Health and the responses of nearly 21,000 teens, as young as seventh-graders, collected in the mid-1990s (the most current data of its kind in the survey). The Mississippi State researchers cross-referenced the month teens said they lost their virginity with responses to questions about the seriousness of their relationships with sexual partners.
In this case, they defined losing virginity as sexual intercourse for the first time between a boy and girl.
The findings ring true to Becky Rose, a 19-year-old student at New York University.
"I'd say we're all fairly vulnerable and needy, and need someone to cling to and love," she says, laughing.
She says it's partly the stress of final exams, followed by the holidays that make her "more emotional" during the holidays. And there's the importance society and families place on relationships.
"Everything you see on TV has people kissing under mistletoe and 'Buy her a diamond - she'll love you!"' says Rose, who concedes that her summertime relationships have been of a more casual nature.
Many experts agree that the holidays have a way of bolstering physical closeness, "whether it's under a mistletoe or in the sack," says Yvonne K. Fulbright, a sex columnist for the student newspaper at NYU.
But she wonders if other factors are at play, too.
"With peer influence still being a big factor in sexual initiation, if one's chums are getting it on during the holidays, it is likely that a teen will want to, too," says Fulbright, a doctoral student in health studies with a master's degree in human sexuality.
Dr. Mark Schuster calls the Mississippi State researchers' findings "a very useful window into seasonal variation in first sexual intercourse."
"For some people, there's something romantic about snow on the ground and cuddling up by the fire," says Schuster, a pediatrician who studies teens and sexual behavior at the UCLA/RAND Center for Adolescent Health Promotion in Los Angeles.
He notes that teens are often less supervised during the holidays, since parents are "often running around buying gifts."
Meanwhile, says Dr. Lynn Ponton, teens generally have more time on their hands.
"This is about kids having sex when they're not worried about school and work and other things," says Ponton, a professor of psychiatry at the University of California at San Francisco and author of the book "The Sex Lives of Teenagers."
Still, she and the others believe teens also romanticize the holidays. Even as a teen herself in the 1960s, Ponton remembers having sex in her parents' living room, next to the Christmas tree. For her, the "forbidden aspect" was the allure.
In a separate 2001 survey, the Centers for Disease Control and Prevention found that nearly 46 percent of high school students said they've had sexual intercourse.
To fully understand what's behind the December teen sex phenomenon, the Mississippi State researchers plan more studies.
Whatever the reasons, experts say the holidays are the perfect time for parents to talk to their teens about sex. "At the very least," says study co-author John Bartkowski, "maybe we should say, 'Leave the lights on.' "
By Martha Irvine