Maternal Factors Related to Infant Motor Development at 4 Months of Age

Exercise during pregnancy and breastfeeding after pregnancy both positively influence a number of infant outcomes. However, whether physical activity during late pregnancy and breastfeeding postpartum influence motor development in the offspring at 4 months of age is unknown. The purposes of this study were to investigate the relationships between several important modifiable factors (i.e., maternal physical activity during late pregnancy and breastfeeding after pregnancy) on infant motor development at 4 months of age. Thirty-three women-infant pairs participated in this prospective longitudinal study. Maternal physical activity was assessed during late pregnancy with wrist-worn accelerometers for 7 consecutive days. Surveys were provided to determine infant feeding practices and other variables that could influence infant motor development. A pediatric board-certified physical therapist assessed infant motor development at 4 months using the Alberta Infant Motor Scale. Infants who were exclusively breastfed had the highest motor development percentiles when compared with those whose mothers were supplementing with or using formula exclusively (exclusive breastfeeding: 64.3 ± 20.1, combination of mother's own milk and formula: 43.5 ± 5.0, exclusive formula: 31.5 ± 15.1, p = 0.001). No associations between physical activity levels during late pregnancy and infant motor development percentiles at 4 months were found (sedentary time: r = -0.057, p = 0.75; light activity: r = -0.074, p = 0.68; moderate activity: r = -0.094, p = 0.60). Infants who were exclusively breastfed had higher motor development percentiles at 4 months of age than those infants whose mothers supplemented with or used formula exclusively. Physical activity levels during late pregnancy were not related to infant motor development percentiles, which suggests that physical activities do not appear to be harmful to infant motor development.