Prenatal determinants of youth physical fitness: Maternal BMI before pregnancy, gestational length, physical activity, and gestational anemia. The UP&DOWN study

OBJECTIVES: Our purpose is to investigate the relative weight of prenatal determinants on children's and adolescents' physical fitness outcomes at different ages. DESIGN: Cross-sectional study with retrospectively collected data. METHODS: We obtained data from 1188 children (571 girls) aged 6-11 years and 1020 adolescents (495 girls) aged 12-17 years. Maternal prenatal determinants were self-reported by mothers. The ALPHA fitness test battery for youth was used to assess offspring's physical fitness (motor fitness, cardiorespiratory fitness and muscular strength). Regression analyses were performed to examine the different physical fitness outcomes. RESULTS: Higher maternal BMI before pregnancy was positively associated with lower physical fitness levels in offspring, regardless of age and sex; offspring of mothers who were physically active before to and during pregnancy exhibited higher physical fitness levels, specifically in female adolescents (all p < 0.05). The length of gestation was positively associated with physical fitness in male adolescents and absence of gestational anemia was related to higher physical fitness levels in female children (all p < 0.05). CONCLUSIONS: Our results show the strongest prenatal determinants of physical fitness in children and adolescents and can contribute to the development of health promotion programs that could start even before children are born.