CHAPTER 29: Calcium Supplementation during Pregnancy and Lactation: Implications for Maternal and Infant Bone Health

It is well accepted that in women with calcium intakes close to current recommendations, the physiologic adaptations for providing calcium to the fetus and infant are largely independent of calcium intake, and that there is no apparent bone benefit for the mother or infant of using calcium supplements. However, in women consuming low calcium diets, and in adolescent mothers, maternal bone adaptations during reproduction have been found to respond to increased calcium intake or calcium supplementation although not always as expected. Moreover, fetal and infant skeletal development has been found to be positively associated to increased maternal calcium intake or supplementation during pregnancy in some but not all studies. These apparently inconsistent results are possibly due to the complex interactions between genetics, diet composition, calcium intake, environment, and lifestyle on maternal and infant bone responses during pregnancy and lactation. In this chapter, studies evaluating the effect of maternal calcium intake during pregnancy and lactation, from the diet and from supplements, on maternal bone outcomes and on fetal and infant bone growth are reviewed. The effect of other factors on bone outcomes and the possible implications for the maternal and infant bone health are considered.