Bone mineral status of lactating mothers of different ages.

To determine the effect of age on the bone mineralization of lactating mothers, 48 healthy mothers were evaluated at 2 and 16 weeks post partum. All mothers were divided into three age groups: less than or equal to 18 years, 19 to 30 years, and greater than 31 years old. At 2 and 16 weeks post partum, blood was drawn for measurement of serum calcium, phosphorus, alkaline phosphatase, and 25-hydroxy vitamin D. Bone mineral content was measured by photon absorptiometry. Dietary history was also recorded. At both 2 and 16 weeks, there were no differences in the serum values or bone mineral content among the three age groups. However, there was a decrease in the bone mineral content between the 2 and 16 weeks' values in the less than or equal to 18 years age group, 1.049 +/- 0.088 versus 0.895 +/- 0.051 gm/cm (p less than 0.05). Dietary intakes were similar among the three groups, but only one of seven mothers less than or equal to 18 years of age met the recommended dietary allowance for calcium or phosphorus, as compared to six of seven older mothers who met the recommended dietary allowance for calcium or phosphorus (p less than 0.01). We conclude that young lactating mothers less than or equal to 18 years old at risk for bone demineralization because of low dietary intakes of calcium or phosphorus.