Relationship of growth in the first five years of life and risk of long bone fracture.

BACKGROUND

Birth size and early childhood growth can affect peak bone mass and later risk of osteoporosis and fracture. We examined the relationship between growth trajectory in the first 5 years of life and the risk of fracture in childhood, adolescence, and early adulthood.

METHODS

We conducted a population-based, case-control study of infants born to residents of Olmsted County, Minnesota, USA between 1976 and 1982. Of 10,938 in the birth cohort, 7892 had at least 1 visit after age 10 y. Cases (n = 1515) with long bone fractures, excluding the femur, after age 6 y were identified. We abstracted childhood weights and heights before age 5.5 y from a stratified random sample of 728 fracture cases in childhood (6-12.9 y), adolescence (13-17.9 y), or adulthood (≥18 y; n = 275 in each group). Weights and heights were categorized into eight age groups between birth and 5.5 y. Control subjects, who had not had a prior long bone fracture were matched with cases for age (within 6 m) and sex.

RESULTS

599 matched sets of cases and controls had weight measurements at birth and in at least 2 age groups and 397 matched sets of cases and controls had height measurements in at least 3 age groups. Two optimal weight-for-age, height-for-age, and weight-for-height trajectory solutions were identified: one sustained above the median (Cluster 1) and one sustained below the median (Cluster 2). Compared with appropriate-for-gestational-age birth size, small-for-gestational-age (SGA) was associated with a reduced risk of fracture (OR 0.44; 95 % CI 0.23-0.82). Cluster 1 weight-for-age (OR 1.19; 0.95-1.49), height-for-age (OR 1.20; 0.90-1.60), and weight-for-height (OR 1.06; 0.80-1.41) trajectories were not associated with subsequent fracture vs Cluster 2. The stratified analysis by fracture age group had similar results, but the relationship with SGA was only significant in the childhood group (6-12.9 y).

CONCLUSION

Growth trajectories in the first 5 y of life were not associated with subsequent fracture. SGA infants had a lower fracture risk between 6 and 13 y of age.