Calcium and bone disorders during pregnancy and lactation.

Mineral metabolism in the mother must adapt to the demand created by the fetus and placenta, which together draw calcium and other minerals from the maternal circulation to mineralize the developing fetal skeleton. Similarly, mineral metabolism must adapt in the lactating woman to supply sufficient calcium to milk and the suckling neonate. Potential adaptations include increased intake of mineral, increased efficiency of intestinal absorption of mineral, mobilization of mineral from the skeleton, and increased renal conservation of mineral. Despite a similar magnitude of calcium demand by pregnant and lactating women, the adjustments made in each of these reproductive periods differ significantly (Fig. 1). These hormone-mediated adjustments normally satisfy the needs of the fetus and infant with short-term depletions of maternal skeletal calcium content, but without long-term consequences to the maternal skeleton. In states of maternal malnutrition and vitamin D deficiency, however, the depletion of skeletal mineral content may be proportionately more severe and may be accompanied by increased skeletal fragility. This article reviews present understanding of the adaptations in mineral metabolism that occur during pregnancy and lactation and how these adaptations affect the presentation, diagnosis, and management of disorders of calcium and bone metabolism. Animal data are cited to fill in the gaps where