Low bone mineral density in small for gestational age infants: correlation with cord blood zinc concentrations.

Twenty eight term small for gestational age (SGA) infants and 18 term appropriate for gestational age (AGA) infants were studied prospectively to assess bone mineral density and cord serum zinc concentrations. Growth and nutritional status were evaluated, and bone mineral density was measured by dual energy x ray densitometry of the lumbar spine. Cord serum zinc, parathyroid hormone, osteocalcin, vitamin D metabolite and mineral concentrations were measured. Growth, nutritional status, and bone mineral density (mean (SD) 0.223 (0.032) vs 0.277 (0.032) g hydroxyapatite/cm2) were significantly low in SGA infants. Bone mineral density was linearly related to growth and nutritional measures. Cord serum zinc concentrations were in the normal range and similar in both groups (mean (SD) 13.86 (3.0) vs 13.43 (2.1) mumol/l). It is suggested that SGA infants may not be zinc deficient. Low bone mineral density could be caused by growth and nutritional status deficiencies, the mechanisms for which could be those that reduce nutrient substrate supply to the fetus.