Parent and child experiences of research participation and retention intentions in a Japanese birth cohort: insights from the Japan Environment and Children's Study (JECS).

BACKGROUND: Long-term birth cohort studies depend on sustained participant engagement. In such studies, children are not only observed over time but also increasingly become participants who experience, interpret, and evaluate their own involvement in research. However, research on continued participation has focused mainly on parental perspectives, with limited attention to children's own views or to similarities and differences between parents and children. Against the growing recognition that people in medical research should be understood as participants rather than passive subjects, this study examined research participation experiences and retention intentions in both parents and children within a Japanese birth cohort.

METHODS: We conducted a questionnaire survey from September to October 2024 within the Japan Environment and Children's Study (JECS). The primary outcome was retention intention. Factors associated with retention intention were analyzed separately for parents and children using ordinal logistic regression. Parent-child concordance in retention intention was assessed descriptively using weighted Cohen's kappa.

RESULTS: Among 1,008 eligible parents of fifth-grade children, 485 responded (response rate, 44%). A large majority of parents (92%) and children (79%) reported willingness to continue participation. Parent-child responses showed moderate agreement (κ = 0.46). In separate adjusted ordinal logistic regression models, stronger parental retention intention was associated with lower perceived questionnaire burden (adjusted odds ratio [aOR]: 5.58, 95% confidence interval [CI]: 3.40-9.17), fewer concerns about possible disagreement with their child (aOR: 5.75, 95% CI: 3.51-9.42), and less difficulty scheduling study activities (aOR: 5.80, 95% CI: 3.50-9.63). In children, stronger retention intention was associated with anticipated gifts (aOR: 7.38, 95% CI: 2.93-18.56), talking with friends about the study (aOR: 6.02, 95% CI: 2.25-16.09), and a desire for peer interaction (aOR: 6.72, 95% CI: 3.39-13.29).

CONCLUSIONS: Parents and children both showed generally positive retention intentions, but disagreement was not negligible. Their retention intentions were associated with different participation-related experiences, suggesting that long-term birth cohort studies should attend to participants' perspectives in age-specific ways. Understanding research participation through both parental and child experiences may help inform more participant-centered engagement strategies and support the quality of long-term cohort research.