Purpose: Obesity prevention is increasingly focused on early childhood, but toddlers have not been well-studied, and children born preterm are frequently excluded. The Play & Grow Cohort was established to investigate child growth in relation to parent-child interactions in mealtime and non-mealtime settings.

Participants: Between December 2017 and May 2019, 300 toddlers and primary caregivers were recruited from records of a large paediatric care provider in Columbus, Ohio, USA. This report describes recruitment of the cohort and outlines the data collection protocols for two toddler and two preschool-age visits. The first study visit coincided with enrolment and occurred when children (57% boys) were a mean (SD) calendar age of 18.2 (0.7) months.

Findings to date: Children in the cohort are diverse relative to gestational age at birth (16%, 28-31 completed weeks' gestation; 21%, 32-36 weeks' gestation; 63%, ≥37 weeks' gestation) and race/ethnicity (8%, Hispanic; 35%, non-Hispanic black; 46%, non-Hispanic white). Caregivers enrolled in the cohort are primarily the child's biological mother (93%) and are diverse in age (range 18-54 years), education (23%, high school or less; 20% graduate degree) and annual household income (27%, <US$20 000 24%, ≥US$90 000). Parent-child interactions were video-recorded during play in the laboratory at 18 months (n=299) and during play, reading and mealtime in the home (n=284) at 24 months. The preschool phase of the study was impacted by COVID-19. Parent-child interactions were video-recorded during play and mealtime at home at 36 months (n=141) and during a standardised buffet meal in the laboratory at 42 months (n=50). Caregivers unable to participate in face-to-face visits due to COVID-19 completed questionnaires.

Future plans: Assessment during middle childhood is being planned. Future visits will include anthropometric measurements and parent-child interactions at mealtime. School-based outcomes are additionally being considered.