Birth weight and time spent in outdoor physical activity during adolescence.
OBJECTIVE
We investigated the association between birth parameters (weight, length, and head circumference) and time spent in physical activity (outdoor and indoor) and screen time (TV viewing, computer, and videogame usage) among adolescents.


METHODS
A longitudinal cohort study surveyed 1794 children in 2004-2005 (median age = 12.7 yr), and 752 were resurveyed 5 yr later in 2009-2010 (age = 17-18 yr). Adolescents completed detailed activity questionnaires. Parents extracted birth parameter data from their child's health record booklet.


RESULTS
After adjusting for age, sex, ethnicity, gestational age, parental education, home ownership, exposure to passive smoking, and body mass index, 12-yr-old children in the highest compared with the lowest quartile of birth weight spent on average approximately 56 and 62 min more in total (Ptrend = 0.02) and outdoor physical activity (Ptrend = 0.02) per week, respectively. Similarly, 12-yr-old children in the high (>4000 g) versus very low (<2000 g) birth weight group spent approximately 1.3 h·wk more in outdoor activity (Ptrend = 0.02). Among those age 17-18 yr, increasing birth weight (lowest to highest quartile) was associated with greater time spent in outdoor physical activity (∼1 h·wk-1, Ptrend = 0.04). Significant associations were not observed between all birth parameters and recreational screen time. Also, no associations were observed between head circumference or birth length with physical activity and screen time.


CONCLUSIONS
Birth weight could be a potential determinant of physical activity, but not of screen time during adolescence. Hence, this could be part of the underlying mechanism between prenatal influences and future disease risk and could have possible clinical implications.
Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, NSW, Australia. bamini.gopinath@sydney.edu.au
Bamini
B
Gopinath
Louise L
LL
Hardy
Louise A
LA
Baur
George
G
Burlutsky
Paul
P
Mitchell
D000293:Adolescent; D001724:Birth Weight; D001827:Body Height; D002648:Child; D003201:Computers; D005260:Female; D006257:Head / Q000033:anatomy & histology; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity; D013177:Sports; D011795:Surveys and Questionnaires; D013690:Television; D013997:Time Factors; D018910:Video Games