Tracking of body size from birth to late adolescence: Contributions of birth length, birth weight, duration of gestation, parents' body size, and twinship

Birth weight has correlated positively with adult body mass index (BMI), bu t rarely have birth length, duration of gestation, or parents' body size be en taken into account. The authors examined tracking of birth length and we ight, adjusted for gestational age, to late adolescence, with special refer ence to parents' height and BMI. Longitudinal information from a nationally representative sample of Finnish twin adolescents (birth cohorts 1975-1979 ) and their parents was collected via questionnaires mailed when the twins were aged 16 years (n = 4,376; 2,062 males, 2,314 females) and 18 years (n = 3,917; 1,742 males, 2,175 females). The twins showed significant tracking of body size from birth to late adolescence, which was greatly influenced by their parents' body size. Height in adolescence was predicted by length and weight at birth and by parents' height, whereas BMI was predicted by bi rth weight and parents' BMI. An especially high risk for overweight was fou nd for subjects of average length but a high weight at birth. These finding s suggest that the intrauterine period has enduring effects on later body s ize but leave unresolved whether these effects are genetic or environmental .