Objective  To examine the prevalence and influencing factors of sexual behaviors among university freshmen in 2018 and to provide evidences for conducting effective sexual health education in the students.

  Methods  Totally 27 114 newly enrolled students of five universities in different geographical regions of China were invited to have an online survey during November 2018. A self-designed questionnaire was used to collect information on demographics, sexual behaviors and associates. Multivariate logistic regression was adopted to analyze influencing factors of sexual behaviors.

  Results  Among the 19 708 valid respondents averagely aged 17.95 ± 0.80 years, 3.48% reported ever having sexual behavior; of the respondents with sexual behavior, 11.82% reported ever exposed to forced sex. The reported prevalence rate of sexual behavior was significantly higher among the boy students than among the girl students (4.77% vs. 2.18%, P < 0.05). Compared to those among the students from comprehensive universities and the Han students, the reported prevalence rate of sexual behavior was significantly higher among medical students (4.25% vs. 3.19%, P < 0.05) and ethnic minority students (4.84% vs. 3.14%, P < 0.05). The results of multivariate logistic regression analysis revealed following risk factors of having sexual behavior for the students: aged ≥ 18 years, male gender, being ethnic minorities, married or having a love affair, in a single-parent family, and with annual household income of more than 100 000 yuan RMB.

  Conclusion  Sexual behaviors among university freshmen should be concerned and comprehensive and specific sexual health education should be conducted among the freshmen in time.