Primary hyperparathyroidism, pregnancy, and neonatal hypocalcemia

Area of Science:

• Endocrinology
• Obstetrics
• Perinatology

Background:

• Primary hyperparathyroidism during pregnancy is linked to severe fetal complications like neonatal tetany.
• Neonatal hypocalcemia is a significant risk in infants born to mothers with hyperparathyroidism.

Purpose of the Study:

• To investigate the pathophysiology of neonatal hypocalcemia in the context of maternal primary hyperparathyroidism.
• To elucidate transplacental calcium dynamics and hormone transfer during pregnancy.

Main Methods:

• Studied calcium ion and hormone transfer across the placenta in pregnant ewes and their fetuses.
• Utilized hysterotomy to access fetal lambs for dynamic studies during the last trimester.

Main Results:

• Calcium ions transfer rapidly across the placenta.
• The placenta effectively blocks the passage of maternal parathyroid hormone and calcitonin to the fetus.
• Maternal hypercalcemia leads to fetal hypercalcemia, suppressing fetal parathyroid gland function.

Conclusions:

• Maternal hypercalcemia in primary hyperparathyroidism causes fetal hypercalcemia and suppressed fetal parathyroid function.
• Interruption of maternal calcium supply post-birth precipitates neonatal hypocalcemia.
• Maternal parathyroidectomy, ideally in the second trimester, can prevent this cycle and ensure fetal calcium homeostasis.