Sexual attitudes, behaviors, and knowledge, attitudes, and practices on infectious disease among only-child and non-only-child college students: A cross-sectional study in first-year students, Jiangsu, China.

Background: Whether differences exist in sexual attitudes, behaviors, and knowledge, attitudes, and practices (KAP) regarding HIV/AIDS, tuberculosis, and hepatitis B between only-child and non-only-child college students in China remains unclear. Methods: From 2019 through 2022, we recruited 33,944 first-year students of Jiangsu origin from 20 universities in Jiangsu Province using a multistage, stratified random sampling design. Data on sexual attitudes, behaviors, and infectious disease KAP were obtained through a structured, self-administered online questionnaire. Propensity-score matching (PSM) was used to compare outcomes between only-child and non-only-child students. Sensitivity analyses were conducted with propensity-score and logistic regression. Results: Overall, 19,525 students (58.96%) were only-children. After PSM, no significant differences were observed between groups across sexual attitudes and behaviors. The odds ratios (ORs) for only-child students, as compared with non-only-child students, were 1.03 (95% CI, 0.961.10) for approving premarital sex, 0.97 (95% CI, 0.911.03) for willingness to use condoms consistently, and 1.20 (95% CI, 0.931.55) for undergoing immediate HIV antibody testing if infection was suspected. The ORs for having engaged in sexual activity, first intercourse at 18 years or older, and consistent condom use were 1.02 (95% CI, 0.861.21), 0.93 (95% CI, 0.651.31), and 1.34 (95% CI, 0.961.87), respectively. No significant differences were found in the proportions of students with high knowledge levels or positive behaviors related to infectious diseases (OR, 0.97; 95% CI, 0.901.04; OR, 1.02; 95% CI, 0.951.10). However, only-child students were more likely to demonstrate positive attitudes toward infectious diseases (OR, 1.10; 95% CI, 1.021.19). Sensitivity analyses supported the robustness of these findings. Conclusions: Only-child and non-only-child college students in China show broadly similar sexual attitudes, behaviors, and infectious disease KAP, with only modest differences in attitudinal domains. Therefore, health education does not need to be individualized based on sibling status; instead, universal and standardized interventions should be prioritized for all college students.