What is the principal mechanism behind hyperparathyroidism during pregnancy?

Hyperparathyroidism during pregnancy is primarily driven by calcium shunting to the fetus. During pregnancy, the demand for calcium increases significantly to support fetal bone development and overall growth. To meet this demand, maternal calcium is often redistributed, leading to a relative increase in parathyroid hormone (PTH) secretion.

This hyperparathyroid state is a physiological adaptation rather than a pathological condition, as the body works to ensure that the growing fetus receives adequate calcium. The maternal parathyroid glands respond to the increased need for calcium by releasing more parathyroid hormone, which helps mobilize calcium from the bones and enhances renal tubular reabsorption of calcium in the mother. This dynamic equilibrium allows for sufficient calcium supply to both maternal and fetal needs.

While increased calcium absorption in the mother plays a role in this process, it is the shunting of calcium specifically to the fetus that is the principal mechanism driving hyperparathyroidism during pregnancy. This highlights how maternal physiology adapts to support fetal development.