Birth weight and body composition in young women: a prospective twin study.
BACKGROUND
The intrauterine environment may be critical for the development of obesity. Alternatively, the same genetic factors may influence both birth weight and adult body composition.


OBJECTIVE
We evaluated the association between birth weight and adult body composition in female twins, which allowed us to control for maternal and genetic influences.


METHODS
Of 447 twin pairs randomly selected from the East Flanders Prospective Twin Survey, 238 pairs, aged 18-34 y, participated. Adult body mass, height, and lean body mass were measured, and the body mass index (BMI), waist-to-hip ratio, and sum of skinfold thicknesses were calculated. The twins were considered as individuals and pairs.


RESULTS
When the twins were considered as individuals, twins who were heavier at birth were taller (3.3 cm/kg greater birth weight) and slightly heavier (1.13 kg/kg greater birth weight) as adults than were lighter twins. They also had more lean body mass and less subcutaneous and abdominal fat at birth. Pairwise comparison showed that for every level of intrapair birth weight difference (> or = 5%, > or = 10%, and > or = 15%), the twin who was heavier at birth was taller in adult life (0.8, 1.2, and 2.0 cm, respectively). When the intrapair birth weight difference exceeded 15%, the heavier twin was also heavier (3.1 +/- 6.08 kg) as an adult than her much lighter sister.


CONCLUSIONS
Birth weight accounts for some of the differences in adult body composition between twins.
Loos
Ruth J F
RJ
Faculty of Physical Education and Physiotherapy, Department of Sport and Movement Sciences, Katholieke Universiteit Leuven, Belgium. ruth.loos@med.kuleuven.ac.be
Beunen
Gaston
G
Fagard
Robert
R
Derom
Catherine
C
Vlietinck
Robert
R
D000328:Adult; D001530:Belgium; D001724:Birth Weight; D001823:Body Composition; D001824:Body Constitution; D001827:Body Height; D005260:Female; D006801:Humans; D011446:Prospective Studies; D011897:Random Allocation; D012042:Registries; D012044:Regression Analysis; D014427:Twins