Suppression and recovery dynamics of infant parathyroid function; clinical outcomes following maternal primary hyperparathyroidism

Abstract

Maternal primary hyperparathyroidism (PHPT), though rare during pregnancy, poses significant and disproportionate risks to the fetus and newborn due to transplacental passage of maternal calcium and parathyroid hormone (PTH). This condition disrupts the fetal mineral regulatory milieu, establishing a critical pathophysiological sequence. Sustained maternal hypercalcemia directly suppresses the development and function of the fetal parathyroid glands in utero, inducing a state of functional dependence on the maternal hypercalcemic environment for calcium homeostasis. Consequently, at delivery, the abrupt termination of both the maternal hypercalcemic drive and placental calcium transfer precipitates a high-risk period for the neonate. The infant, born with profoundly suppressed parathyroid reserve, faces a substantial challenge in mounting an adequate PTH secretory response to the sudden drop in calcium supply. This pathophysiological lag universally triggers neonatal hypocalcemia, the severity and duration of which are intrinsically linked to the depth and chronicity of in utero parathyroid suppression, as well as the individual neonate’s capacity for parathyroid functional recovery. Clinical manifestations can range from asymptomatic biochemical hypocalcemia to severe, life-threatening complications including seizures, tetany, apnea, and cardiomyopathy. Understanding this mechanistic pathway, from maternal hypercalcemia to fetal gland suppression and the predictable postnatal hypocalcemic crisis is paramount. It underscores the necessity for vigilant prenatal diagnosis of maternal PHPT, meticulous intrapartum planning, and intensive, protocol-driven neonatal monitoring and calcium/active vitamin D replacement strategies to prevent significant neonatal morbidity. Early recognition of this iatrogenic dependence is crucial for optimizing outcomes in affected offspring.

Keywords: Maternal, Infant, Neonatal, Parathyroid, Calcium homeostasis, Hypocalcemia, hypercalcemia, Hyperparathyroidism, Parathyroid hormone, Neonatal outcomes, Maternal