“…However, because PTH concentration is lowered or unchanged in pregnant women, it is unlikely to be primarily responsible for the increase in 1,25(OH) 2 D seen in pregnancy (3) , although it remains responsive to changes in Ca load (147) . Although hormones, such as oestrogen, prolactin, growth hormone and insulin-like growth factor-I, have the ability to induce 1-a-hydroxylase activity (174,175,181) , it is likely that PTHrP has a key role (3,179,182) . This activates the PTH/PTHrP receptor and therefore exhibits PTH-like effects, including stimulation of renal 1,25(OH) 2 D production (182,183) .…”