Child restraint system ownership and use in selected urban districts of Shenzhen and Shantou: a cross-sectional comparison

Since 2015, Shenzhen has required child restraint system (CRS) use for children under four, while most other cities in China, including Shantou, rely only on non-compulsory national recommendations. This study compared CRS ownership and use and associated factors among participants recruited from selected urban districts of the two cities to provide policy-relevant evidence for improving child passenger safety in China. A cross-sectional survey was conducted in 2023 among car-owning families with children aged 0–10 years recruited from selected urban districts of Shenzhen and Shantou ( N = 1,963). Data were collected on CRS ownership, CRS use behavior, caregiver safety knowledge, attitudes toward mandatory CRS use, awareness of national CRS legislation, and reported exposure to traffic-police CRS reminders. Multivariable logistic regression, sensitivity analyses using stricter CRS-use definitions, and propensity score matching (PSM) were conducted to examine the robustness of the city difference in CRS use. CRS ownership and use were higher in Shenzhen than in Shantou (75.88% vs. 55.80%; 63.75% vs. 43.34%). Families in Shantou had lower odds of CRS use than those in Shenzhen after adjustment for demographic characteristics and measured behavioral and policy-perception factors (a OR = 0.42; 95% CI : 0.33–0.53), with a similar association observed in the baseline demographic model. CRS use declined with child age; children aged 7–10 years had lower odds of CRS use than those aged 0–3 years (a OR = 0.57; 95% CI : 0.43–0.76). Awareness of the national CRS-related provision, support for mandatory use, reported exposure to traffic-police CRS reminders, and higher CRS safety knowledge were positively associated with CRS use. The city difference remained after PSM and sensitivity analyses. Among participants recruited from selected urban districts, CRS ownership and use were higher in Shenzhen than in Shantou, including among children aged 0–3 years, but use declined among older children in both cities. The city difference may partly reflect differences in local policy contexts; however, city-level socioeconomic, transportation-related, and other contextual factors cannot be separated. Improving CRS use may require integrated strategies combining clearer policy requirements, enforcement communication, caregiver education, and practical support for sustained age-appropriate restraint use.