Abstract:
Studies of pregnant women indicate that the fetal calcium demand is met largely by intestinal calcium absorption, which from early pregnancy onward more than doubles. The studies of biochemical markers of bone turnover, DXA, and ultrasound are inconclusive, but suggest that the maternal skeleton also contributes calcium to the developing fetus. In contrast, during lactation, skeletal calcium resorption is the dominant mechanism by which calcium is supplied to the breast milk; renal calcium conservation is also apparent. Lactation produces an obligatory skeletal calcium loss regardless of maternal calcium intake, but the calcium is completely restored to the skeleton after weaning through mechanisms that are not understood. The adaptations during pregnancy and lactation lead to novel presentations and management issues for known disorders of calcium and bone metabolism, such as primary hyperparathyroidism, hypoparathyroidism, and vitamin D deficiency. Finally, although some women experience fragility fractures as a consequence of pregnancy or lactation, in most women the changes in calcium and bone metabolism during pregnancy and lactation are normal and without adverse consequences in the long-term. © 2005 Elsevier Inc. All rights reserved.