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Sex Differences in Birth Weight and Physical Activity in Japanese Schoolchildren
Mitsuya Yamakita1, Miri Sato2, Kohta Suzuki3
1College of Liberal Arts and Sciences, Kitasato University.
Insights
Lower birth weight is linked to reduced physical activity (PA) in school-aged girls, but not boys. This finding highlights the importance of considering birth weight for public health strategies aimed at preventing physical inactivity in girls.
Area of Science:
- Pediatric Health
- Public Health
- Epidemiology
Background:
- Lower birth weight (BW) is a known risk factor for chronic diseases later in life.
- Physical activity (PA) is hypothesized as a key mediator linking BW to long-term health outcomes.
- The relationship between BW and PA in childhood remains unclear.
Purpose of the Study:
- To investigate the association between birth weight and physical activity levels in school-aged children in Japan.
Main Methods:
- Analysis of data from a prospective birth cohort study (Project Koshu) including children born between 1996-2002.
- Collection of birth weight data from the Maternal and Child Health Handbook.
- Assessment of childhood physical activity using self-reported questionnaires in participants aged 9-15 years.
- Statistical analysis using ANCOVA for exercise duration and Poisson regression for meeting recommended PA levels.
Main Results:
- Data from 657 children were analyzed, with a follow-up rate of 77.6%.
- Girls with low birth weight exhibited significantly lower physical activity levels (5.8 hours/week) compared to normal birth weight girls (11.4 hours/week).
- Low birth weight girls were also more likely to not meet recommended PA guidelines (PR 1.57, 95% CI 1.14-2.16).
- No significant association was found between birth weight and PA in boys.
Conclusions:
- Low birth weight is associated with reduced physical activity in school-aged girls, but not boys.
- Considering birth weight early in life may be a crucial public health strategy to prevent physical inactivity among girls.
- Further research may explore interventions targeting this vulnerable group.
Background:
Lower birth weight (BW) is associated with increased chronic disease risk later in life. Previous studies suggest that this may be mediated principally via physical activity (PA). However, the association between BW and PA in children has not been clarified. The purpose of this study was to examine the association between BW and PA in school-aged children in Japan.
Methods:
Participants were children from a prospective birth cohort study (Project Koshu) who were born from 1996 through 2002 in rural Japan. BWs were obtained from the Maternal and Child Health Handbook. Data on PA during childhood were collected using a self-reported questionnaire when participants were 9-15 years of age in July 2011. Analysis of covariance was used to evaluate exercise duration; Poisson regression analysis was used to evaluate if the recommended PA amount was met.
Results:
Data from 657 children (boys: 54.8%, follow-up rate: 77.6%) were analyzed. Compared with the normal BW group, only girls in the low-BW group had significantly lower PA level (normal BW, 11.4 [standard error, 1.0] hours/week; low BW, 5.8 [standard error, 3.6] hours/week, P = 0.010), and were more likely to not meet the recommended PA level (prevalence ratio 1.57; 95% CI, 1.14-2.16).
Conclusion:
Low BW was associated with a lower PA level in school-aged girls but not boys. Earlier consideration of BW may be an important public health strategy to prevent physical inactivity in school-aged girls.
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