Fertility and Pregnancy Outcomes in Primary Hyperparathyroidism: Observations From a Large Insured Population.

Context: Primary hyperparathyroidism (PHPT) has initially been implicated in adverse maternal and neonatal outcomes, while subsequent population studies have failed to show an association.

Objective: This work aimed to compare maternal, pregnancy, and neonatal outcomes in patients with and without PHPT.

Methods: A retrospective matched-cohort study (2005-2020) was conducted at an integrated health-care delivery system in Southern California. Women aged 18 to 44 years were included. Patients with a biochemical diagnosis of PHPT were matched 1:3 with eucalcemic controls (non-PHPT). Main outcome measures included achievement of pregnancy, pregnancy outcomes (including rates of abortion, maternal complications), and neonatal outcomes (including hypocalcemia, need for intensive care).

Results: The cohort comprised 386 women with PHPT and 1158 age-matched controls. Pregnancy rates between PHPT and control groups were similar (10.6% vs 12.8%). The adjusted rate ratio of pregnancy was 0.89 (95% CI, 0.64-1.24) (PHPT vs non-PHPT). Twenty-nine pregnancies occurred in women with coexisting PHPT and 191 pregnancies occurred in controls, resulting in 23 (79.3%) and 168 (88.0%) live births, respectively (P = .023). Neonatal outcomes were similar. Live birth rates were similar (86.4%, 80%, 79.2%) for those undergoing parathyroidectomy prior (n = 22), during (n = 5), or after pregnancy/never (n = 24). Among patients who underwent parathyroidectomy during pregnancy, no spontaneous abortions occurred in women entering pregnancy with peak calcium less than 11.5 mg/dL (2.9 mmol/L).

Conclusion: We observed no difference in pregnancy rates between women with or without PHPT. Performing parathyroidectomy before pregnancy or during the second trimester appears to be a safe and successful strategy, and adherence to this strategy may be most critical for patients with higher calcium levels (≥11.5 mg/dL [2.9 mmol/L]).