RESUMO
Primary hyperparathyroidism is rarely encountered during pregnancy but its prompt diagnosis and treatment if encountered during pregnancy is important because it can carry considerable morbidity not only for the mother but also for the fetus. It tends to remain undiagnosed because 50~80% of the patients are asymptomatic. Even if they do demonstrate symptoms, those are often nonspecific. The other reason for non-diagnosis is masking of hypercalcemia due to the change of calcium homeostasis during pregnancy. Neonatal tetany can be a clue for the presence and diagnosis maternal hyperparathyroidism. The asymptomatic patient who is diagnosed postpartum when her newborn is symptomatic should undergo elective parathyroidectomy to avoid future complication. We experienced a woman with undiagnosed primary hyperparathyroidism during pregnancy whose two children suffered neonatal tetany. We report this case along with a review of literature on primary hyperparathyroidism in pregnancy and calcium homeostasis during pregnancy.