Parent-generated data from Brazilian home environment: Mapping emergence and transition in infant locomotor development in two age cohorts (5-11 and 9-15 months).

Caregiver-infant interactions shape the home environment in intentional and unintentional ways, creating different opportunities for action. In this sense, research should prioritize real-world contexts. The study aimed to characterize the emergence and transition of locomotor behaviors within the developmental pathways of typically developing Brazilian infants across two age cohorts. Group 1 included nineteen infants followed from five to eleven months-old and Group 2, eighteen infants from nine to fifteen months-old. Families recorded approximately eight minutes of infant home free play every two weeks. Locomotor bouts were classified as belly crawling, hands-and-knees crawling, hands-and-feet crawling, asymmetrical crawling, knee-locomotion and walking. Emergence was defined as the first appearance of a behavior in the repertoire, and transition as a change in behavioral predominance between recordings. Interindividual variability was observed, with fifteen emergence and twelve transition pathways for Group 1 and eight emergence and thirteen transition pathways for Group 2. Most emergence and transition events involved hands-and-knees crawling and walking. Non-traditional behaviors also contributed to pathways. Asymmetrical crawling emerged for most infants from Group 1. Transition events occurred in multiple directions, from less to more complex behaviors and vice versa. Locomotor development was characterized by diversity and non-linearity in behavioral preference and sequencing.