Retention of second-generation participants in intergenerational longitudinal cohort studies: a systematic mapping review

Pregnancy and birth cohorts are unique forms of longitudinal studies where the primary respondent (first-generation) can change over time from the pregnant/birthing parent to the youth (second-generation). Obtaining data directly from second-generation participants is important as youth become more independent; however, retention rates and optimal strategies to engage second-generation participants are unknown.

A systematic mapping review was conducted to identify prospective cohort studies or randomized controlled trials with follow-up until the second-generation participant reached at least 5 years of age. Meta-analysis was used to derive pooled retention rates for first- and second-generation participants. Sub-group meta-analysis and meta-regression were used to assess which factors were associated with retention in second-generation participants.

Seventy-three eligible studies were identified, of which 40 (54.8%, N = 298 446 first-generation participants, N = 131 679 second-generation participants) collected data directly from second-generation participants. Retention rates for both first- and second-generation participants steadily decreased over time, with higher rates of engagement from second-generation participants observed prior to age 18. Ever providing compensation for participating in data collection, ever facilitating referrals to health professionals, and ever providing participants with free medical/psychological assessments were associated with improved retention at some (but not all) time points.

Intergenerational research is critical to understanding multiple aspects of human development. Retention strategies that provide a tangible benefit to participants may facilitate retention of youth participants in intergenerational studies, and youth perspectives should be considered to ensure that study retention strategies are optimized to reflect their values and preferences.