RESUMO
ABSTRACT OBJECTIVE To assess risk factors associated with motor development delay at three months of age. METHODS Cross-sectional study with mothers and their three-month-old babies in Southern Brazil. The Bayley-III Scale of Infant and Toddler Development (BSID-III) and the Alberta Infant Motor Scale (AIMS) were used to assess motor development. RESULTS We evaluated 756 mothers and their three-month-old babies. The overall mean motor development assessed by the BSID-III and the AIMS was 104.7 (SD 13.5) and 55.4 (SD 25.4), respectively. When assessed by the BSID-III, the lowest motor development scores were among babies born by cesarean delivery (p = 0.002), prematurely (p < 0.001), and with low birth weight (p < 0.001). When assessed by the AIMS, babies born prematurely (p = 0.002) and with low birth weight (p=0.004) had the lowest motor development means. After a cluster analysis, we found that babies born by cesarean delivery, with low birth weight, and prematurely had more impaired motor development compared with children born without any risk factors. CONCLUSION Identifying risk factors allows the implementation of early interventions to prevent motor development delay and, therefore, reduce the probability of other future problems.