Associations of birth weight and physical activity with sex steroids in preschool Japanese children

摘要

Purpose: We aimed to assess the association of body size at birth or physical activity with sex steroid levels, independent of body mass among young children. Methods: The cross-sectional study was conducted in 2006. Subjects were 230 boys and 198 girls, aged 3-6 years. Birth weight was based on parents' reports. Questions about physical activity focused on outdoor playtime. Urinary estrone, estradiol, testosterone, and 5-androstene-3β,17α diol (3β,17α-AED) levels were measured by liquid chromatography - electrospray ionization tandem mass spectrometry. Urinary dehydroepiandrosterone level was measured with a radioimmunoassay. Results: After adjustments for age and BMI, girls with lower birth weight had higher testosterone (trend p = 0.038) and 3β,17α-AED (trend p = 0.028). Girls with low birth weight and high birth weight had higher estrone (p = 0.014) and estradiol (p = 0.074) than those who had middle birth weight. Boys who were physically active had lower testosterone (p = 0.028) and 3β,17α-AED (p = 0.003) than those who were not active. Girls who were physically active had lower estrone (p = 0.015). Conclusions: Sex steroid levels in childhood might be affected by body size at birth or by physical activity during childhood. These effects might differ by sex.