Julie L. Daniels

Background Current knowledge about parental reasons for allowing child participation in research comes mainly from clinical trials. Fewer data exist on parents’ motivations to enrol children in observational studies. Objectives Describe reasons parents of preschoolers gave for participating in the Study to Explore Early Development (SEED), a US multi‐site study of autism spectrum disorder (ASD) and other developmental delays or disorders (DD), and explore reasons given by child diagnostic and behavioural characteristics at enrolment. Methods We included families of children, age 2–5 years, participating in SEED ( n = 5696) during 2007–2016. We assigned children to groups based on characteristics at enrolment: previously diagnosed ASD; suspected ASD; non‐ASD DD; and population controls (POP). During a study interview, we asked parents their reasons for participating. Two coders independently coded responses and resolved discrepancies via consensus. We fit binary mixed‐effects models to evaluate associations of each reason with group and demographics, using POP as reference. Results Participants gave 1–5 reasons for participation (mean = 1.7, SD = 0.7). Altruism (48.3%), ASD research interest (47.4%) and perceived personal benefit (26.9%) were most common. Two novel reasons were knowing someone outside the household with the study conditions (peripheral relationship; 14.1%) and desire to contribute to a specified result (1.4%). Odds of reporting interest in ASD research were higher among diagnosed ASD participants (odds ratio [OR] 2.89, 95% confidence interval [CI] 2.49–3.35). Perceived personal benefit had higher odds among diagnosed (OR 1.92, 95% CI 1.61–2.29) or suspected ASD (OR 3.67, 95% CI 2.99–4.50) and non‐ASD DD (OR 1.80, 95% CI 1.50–2.16) participants. Peripheral relationship with ASD/DD had lower odds among all case groups. Conclusions We identified meaningful differences between groups in parent‐reported reasons for participation. Differences demonstrate an opportunity for future studies to tailor recruitment materials and increase the perceived benefit for specific prospective participants.