Research Article: Decreased Bone Mineral Density in Adults Born with Very Low Birth Weight: A Cohort Study

Date Published: August 25, 2009

Publisher: Public Library of Science

Author(s): Petteri Hovi, Sture Andersson, Anna-Liisa Järvenpää, Johan G. Eriksson, Sonja Strang-Karlsson, Eero Kajantie, Outi Mäkitie, Tom W. J. Huizinga

Abstract: Petteri Hovi and colleagues evaluate skeletal health in 144 adults born preterm with very low birth weight and show that as adults these individuals have significantly lower bone mineral density than do their term-born peers.

Partial Text: The last trimester of pregnancy is crucial for fetal bone mineralization. Fetal and maternal mineral metabolism is uniquely adapted to provide sufficient calcium and other minerals to fully mineralize the fetal skeleton before birth [1]. The interplay of minerals and calciotropic hormones is important, but for appropriate intra-uterine skeletal development, active fetal movement against the uterine wall is needed as well. Mineralization occurs rapidly in late gestation; up to 80% of the body calcium of a term newborn accrues during the third trimester [2].

We show that young adults born prematurely at VLBW (<1,500 g), have, at ages 18 to 27 y, lower lumbar spine, femoral neck, and whole body BMD than do their term-born peers of normal birth weight. Differences in BMD Z scores between groups were considerable: up to 0.51 units in the lumbar spine and 0.56 units in the femoral neck. VLBW adults' smaller body size and lower exercise intensity explained only a portion of these differences; after adjusting for height, VLBW participants' lumbar spine Z score was still almost twice as likely to fall below −1.0. Lumbar spine BMD turned out to be lower also in an alternative analysis using BMAD, an index that corrects for bone size. Shorter final body height has been also previously reported in both VLBW men (3–5 cm) and women (1–8 cm) [26]–[28]. Small body size has been suggested, by some studies, to explain low bone mass in peripuberty and adolescence of those born premature [3],[4],[5],[29], whereas Wang et al. showed that VLBW individuals had reduced bone mass at ages 5 to 10 y even after adjustment for height, lean mass, or bone area [30]. Our results support the suggestion that VLBW adults attain only subnormal peak bone mass although this may partially be attributable to their small body size. Source:


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