Intra-Individual Variability in Gross Motor Development in Healthy Full-Term Infants Aged 0–13 Months and Associated Factors during Child Rearing

Abstract

The gross motor development of a typically developing infant is a dynamic process, the intra-individual variability of which can be investigated through longitudinal assessments. Changes in gross motor development vary, according to the interaction of multiple sub-systems within the child, environment, task setting, and experience or practice of movement. At present, studies on environmental factors that influence gross motor development in full-term infants over time are limited. The main aim of this study was to investigate environmental factors affecting intra-individual variability from birth to 13 months. The gross motor development of 41 full-term infants was longitudinally assessed every month from the age of 15 days using the Alberta Infant Motor Scale. Parents were interviewed monthly about environmental factors during childcare. Infants showed fluctuations in the percentile of gross motor development, and no systematic pattern was detected. The total mean range of gross motor percentile was 65.95 (SD = 15.74; SEM = 2.28). The percentiles of gross motor skills over the 14 assessments ranged from 36 to 93 percentile points. Factors that were significantly associated with the gross motor development percentile were the use of a baby walker (Coef. = −8.83, p ≤ 0.0001) and a baby hammock (Coef. = 7.33, p = 0.04). The use of baby hammocks could increase the gross motor percentile by 7.33 points. Although the usage of a baby walker is common practice in childcare, it may cause a decrease in the gross motor percentile by 8.83 points according to this study. In conclusion, healthy full-term infants exhibited a natural variability in gross motor development. Placing infants in a baby walker during the first year of age should be approached with caution due to the risk of delayed gross motor development.

Effects of Play in an Upright Position on Intra-Individual Variability of Gross Motor and Language Development in Institutionalized Infants

“…After participating in the play program for a 3-month period, healthy orphaned infants in this study were able to show wider intra-individual variability of gross motor developmental percentiles. The wide intra-individual variability was in line with previous longitudinal studies indicating that developing infants typically exhibit variability in terms of gross motor percentile from 3 to 13 months [ 11 , 12 , 13 , 33 , 41 ], while intra-individual variability of gross motor development in the control group was quite stable, similar to previous studies on orphaned infants who displayed narrow intra-individual variability [ 19 , 20 ]. The mean value of intra-individual variability within 12 months in the study of Prommin et al was 55.4 percentile, while the mean intra-individual variability within 3 months of the current study was 34.3 percentile ( Table 3 ).…”

Three decades of infant motor development: Cohort effects in motor skill onsets.

“…Presently, the most common motor skill assessment is the Alberta Infant Motor Scale (AIMS) which established norms for motor skill acquisition using a sample from Canada in 1992 (Piper et al, 1992). Internationally, researchers who used the AIMS consistently found that infants from their populations did not achieve milestones at the same ages as the infants from Alberta, motivating them to adjust or create their own norms (Kepenek-Varol et al, 2020;Manuel et al, 2012;Saccani & Valentini, 2013;Saccani et al, 2016;Størvold et al, 2013;Tupsila et al, 2020;van Iersel et al, 2020). Just as it was suggested in the early 1990s, we suggest again in 2023 that the established norms from 1992 may not necessarily be currently applicable, even for the same population.…”