Postpartum Thyroiditis: Long-Term Follow-Up

Abstract

Objective: To determine the incidence of persistent hypothyroidism (PH) after a long follow-up in 45 patients with postpartum thyroiditis (PPT) from a nonselected population of 641 pregnant women (PPT incidence 7.8%) and the clinical and biochemical factors associated with PPT evolution. Design and patients: The 45 women who developed PPT were followed for 8.1 ± 2.2 years after delivery. Measurements: Age at delivery, family and personal history, smoking, newborn gender, breast-feeding, and PPT course were recorded. Thyrotropin (TSH) and free thyroxine (T₄) concentrations and antithyroid antibodies were evaluated at each visit. PH was considered when it persisted one year after being diagnosed. Results: Fourteen of 45 patients with PPT developed PH with a probability of 56% after a PPT episode with hypothyroidism. None of the patients who developed hyperthyroidism alone during PPT evolved to PH. PH risk was higher if the newborn was a girl (relative risk [RR] 3.88) and increased for each additional TSH unit during PPT and for every additional year of the mother’s age. Conclusions: The probability of developing PH after a PPT with hypothyroidism episode is 56%. PPT screening in all women permits us to establish levothyroxine treatment, if necessary, before a new pregnancy.