Relations between birth weight and hip bone strength indices in a group of adolescent girls.

OBJECTIVE: The aim of this study was to explore the relations between birth weight and hip bone strength indices in a group of adolescent girls. METHODS AND RESULTS: This study included 26 adolescent girls (153 +/- 2.9 years old). Weight and height were measured and body mass index (BMI) was calculated. Birth weights were obtained from obstetric records. Body composition and BMD were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate bone geometry, DXA scans were analyzed at the femoral neck (FN), the intertrochanteric (IT) region and the femoral shaft (FS) by the Hip Structure Analysis (HSA) program. Cross sectional area (CSA), an index of axial compression strength, cross sectional moment of inertia (CSMI), an index of structural rigidity and section modulus (Z), an index of bending strength, were measured from bone mass profiles. Birth weight was positively correlated to CSA, CSMI and Z of the three sites (FN, IT and FS). However, the positive associations between birth weight and HSA variables disappeared after controlling for body weight. CONCLUSION: In this population, the positive associations between birth weight and hip bone strength indices disappear after controlling for body weight.