"Given the potential for negative emotional and physical health outcomes as a result of sexual hookups, including unplanned pregnancy and depression, it is important to identify the factors that influence hookup behavior," said lead author Robyn L. Fielder, M.S., a research intern at The Miriam Hospital's Centers for Behavioral and Preventive Medicine.

Fielder and her team surveyed 483 incoming first-year female college students about their risk behaviors, personality traits and social environment. Specific questions covered the students' sexual behavior, hookup attitudes and intentions, self-esteem, religious beliefs, parents' relationship status, alcohol and marijuana use, smoking, impulsivity and sensation-seeking behavior. Researchers followed up with the women monthly for eight months.

"Our findings suggest hooking up during the first year of college is influenced by pre-college hookups, personality, behavioral intentions, the social and situational context, family background and substance use patterns -- particularly marijuana use," said Fielder.

According to Fielder, this is believed to be the first study to explore marijuana use as a predictor of hooking up, even though previous research has linked marijuana use to risky sexual behavior and marijuana has been shown to impair judgment and reduce inhibitions.

But overall, pre-college hookups emerged as the strongest predictor of hooking up during freshmen year, suggesting early hookup experiences may provide a personal model for future behavior.

"These findings suggest that women's hookup behavior during the first year of college may influence their hookup behavior later in college," said Fielder. "That's why the transition to college is an important time for health care professionals to provide sexual health information and resources to help women make informed choices."

But at the same time, she said it's also important to consider the array of individual, social and contextual factors when studying hookup behavior. "Focusing on any one area of influence fails to capture the complicated matrix of forces that influence young adults' relationship decisions," Fielder added.