Identification of predictors of objectively measured physical activity in 12-month-old British infants: a machine learning driven study

Abstract

BackgroundDespite physical activity playing an important part in enhancing and maintaining good health throughout the life course, little is known about it in young children. This study aimed to identify predictive factors associated with intensity of physical activity in 12-month-old infants. MethodsParents of participants in the Environments for Healthy Living birth cohort study were approached. We collected data on physical activity from 141 infants using ankle-mounted tri-axial accelerometers (GENEActiv, Kimbolton, UK) in the unit of signal vector magnitude (SVM) score over 7 consecutive days, and linked the data to abstracts of postnatal notes and electronic medical records. To identify factors associated with intensity of physical activity, a machine learning framework was used to process the complex data, in which a multivariate linear regression model was fitted on a set of selected predictors using the ReliefF feature ranking algorithm to distinguish lower and higher active groups. FindingsThe physical activity level of mean SVM score ranged from 0·677 to 4·932 in the lower active group (n=70) compared with 4·975 to 10·628 in the higher active group (n=71)]There were more boys than girls in the active group (49 vs 22) and more girls than boys in the inactive group (42 vs 28; r2=0·615). High intensity of physical activity in 12-month-old infants was associated with larger infant length (12 months; 95% CI 13·47 to 29·38), higher maternal blood pressure (12 months; 5·54 to 27·70), longer gestation period (13·75 to 34·47), higher breastfeeding duration (weeks; 2·33 to 12·84,), more movement during sleep (1·25 to 2·32), and high intake of vegetables (0·19 to 4·44) and juice (0·04 to 1·67) and less consumption of adult crisps (0·05 to 0·73). InterpretationThe findings suggest that at age 12 months boys are more active than girls and that both gestational and postnatal environment factors, such as preterm birth (<37 weeks), dietary habits, and longer breastfeeding duration, are important predictors of intensity of physical activity in 1 year olds. However, a limitation of this study is the requirement for infants to wear the accelerometer for 7 full days; all the children with fewer than 7 days' wear were excluded from the study. These findings can help inform interventions to promote healthier lifestyles in young families. FundingGrowing Up in Wales birth cohort, National Centre for Population Health and Wellbeing Research (CA02), Centre for Improvement in Population Health through E-records Research (CIPHER) within the Farr Institute of Health Informatics Research (MR/K006525/1).