Figure 4.Schematic illustration of the longitudinal changes in calcium, phosphate, and calcitropic hormone levels that occur during human pregnancy. Normal adults ranges are indicated by the shaded areas. The progression in PTHrP levels has been depicted by a dashed line to reflect that the data are less complete.(From Kovacs CS, Kronenberg HM. Maternal-fetal calcium and bone metabolism during pregnancy, puerperium, and lactation. Endocrine Revs 1997;18:832.)