Bone Abstracts

Objectives: While nutritional rickets is traditionally associated with vitamin D deficiency, a number of other etiological factors have been proposed, including low calcium intake. Maternal nutrition can affect fetal and infant skeletal growth and development. Our aim was to determine the relationship between maternal bone density and rickets in Nigerian children.

Methods: We measured areal forearm bone mineral density (BMD) in 56 and 131 mothers of children with and without nutritional rickets, respectively. Active rickets was confirmed with radiographs of the wrists and knees. Pregnancy and lactation status were recorded, but bone density measurements were not performed in the first trimester of pregnancy. Using logistic regression, we assessed the association of maternal forearm bone density, controlling for parity, pregnancy and lactation status, duration of most recent breastfeeding, age of menarche, and maternal age with nutritional rickets.

Results: The median (range) age of mothers was 30 years (17–47 years), and parity was 4 (1–12). A total of 36 (19%) were pregnant and 55 (29%) were currently breast feeding. Mean (±S.D.) distal forearm BMDs were 0.321±0.057 and 0.314±0.052 g/cm² in mothers of children with and without rickets respectively (P=0.43). Proximal 1/3 forearm BMDs were 0.719±0.071 and 0.713±0.070 g/cm² respectively (P=0.58). Bone mineral content and bone area were not significantly different between the two groups. Neither the distal nor proximal 1/3 forearm maternal BMD was associated with nutritional rickets in multivariate logistic regression (P=0.42 and 0.84 respectively). In the adjusted analysis, rickets was associated with shorter duration of breast feeding (OR 0.90 for each additional month; P=0.01) and use of lead-containing eye cosmetics by mothers (OR 4.78; P=0.01). Maternal age, parity, age of menarche, and BMI were not associated with having had a child with rickets in multivariate analysis.

Conclusion: There was no relationship between maternal BMD and nutritional rickets in children. However, early discontinuation of breast feeding and use of lead-containing eye cosmetics may increase the risk of nutritional rickets in Nigerian children.