Examining the Multifaceted Factors Underlying Infant Gross Motor Development: A Structural Equation Model

This study employed a descriptive, cross-sectional design to examine individual, maternal, and environmental predictors of gross motor development in infants aged 3 to 8 months. Participants Participants were 541 parent–infant dyads recruited consecutively from Shiraz University of Medical Sciences and referred to the University Developmental Care Center. The sample included infants aged between 3 and 8 months (M = 5.4 months, SD = 1.6). The aim of sampling was to capture a broad range of socio-economic backgrounds within the Iranian context, for example ethnicity, that presented in Table 1. Inclusion criteria were: (a) full-term birth (37–42 weeks’ gestation), (b) age between 3 and 8 months at the time of assessment, and (c) absence of known developmental disorders or chronic medical conditions. Exclusion criteria included: (a) preterm birth or low birth weight (< 2500 g), (b) presence of congenital anomalies or neurological disorders, and (c) gross motor scores at least two standard deviations below the mean on the Ages and Stages Questionnaire (ASQ). All eligible infants were screened for gross motor development using the ASQ. Infants meeting exclusion criteria based on ASQ scores were excluded from further participation. Procedure Parents of eligible infants were informed about the purpose and procedures of the study and provided written informed consent prior to participation. Data collection was conducted at the University Developmental Care Center. Parents completed a set of standardized questionnaires assessing infant characteristics, maternal factors, and environmental conditions. Completed questionnaires were returned to the Center for data processing and analysis.