Typical general movements at 2 to 4 months: Movement complexity, fidgety movements, and their associations with risk factors and SINDA scores

Background: Movement complexity and the presence of fidgety movements (FMs) during general movements (GMs) both reflect aspects of neurological integrity in early infancy.

Aim: To assess interrelations between the degree of movement complexity and characteristics of FMs during typical GMs and to investigate associations between mildly impaired GMs and risk factors and neurodevelopmental condition.

Study design: Observational cohort study.

Subjects: 283 infants (25 born preterm) at 2-4 months corrected age, representative of the general Dutch population.

Outcome measures: GMs were classified in terms of GM-complexity (normal or mildly abnormal (MA)) and FMs (clearly present, sporadic, or exaggerated). Concurrent neurological, developmental and socio-emotional status were measured with the Standardized Infant NeuroDevelopmental Assessment (SINDA).

Results: Infants with MA GM-complexity had a higher risk of having sporadic FMs and exaggerated FMs. Perinatal complications were not associated with mildly impaired GMs. MA GM-complexity was associated with advanced maternal age (adjusted OR = 2.29 [1.11, 4.76]) and having a non-native Dutch mother (adjusted OR = 2.93 [1.29, 6.64]). It was also associated with atypical neurological (OR = 7.62 [3.51, 16.54]) and developmental scores (OR = 2.38 [1.16, 4.88]). Sporadic and exaggerated FMs were associated with low-to-middle maternal education (adjusted OR = 2.88, [1.45, 5.72]) and having a non-native Dutch father (adjusted OR = 7.16 [1.41, 36.32]), respectively. However, neither sporadic nor exaggerated FMs were associated with the SINDA outcomes.

Conclusions: GM-complexity and FMs are two interrelated but different aspects of GMs. Mild impairments in GM-complexity and FMs share a non-optimal socio-economic background as risk factor, but only MA GM-complexity is associated with a concurrent non-optimal neurodevelopmental condition.