Objectives/Hypothesis: Thyroid cancer, with 6% to 10% of cancer diagnoses, is one of the most common malignancies during pregnancy. Its treatment poses a risk for the pregnancy, as the thyroid gland plays a crucial role in the evolution of pregnancy. The aim of this study is to evaluate treatment of primary well-differentiated thyroid carcinoma during pregnancy and fetal and maternal outcomes. Study Design: This is an international cohort study. Methods: Primary thyroid cancer patients were identified from the database of the International Network on Cancer, Infertility, and Pregnancy registration study. Data on histopathological characteristics, diagnostic and therapeutic interventions, outcome (obstetrical, neonatal, and maternal) and maternal follow-up were analyzed. Results: Thirty-five patients with well-differentiated thyroid carcinoma were eligible. All 35 patients underwent surgery, 29 (83%) of which during pregnancy. Procedures during pregnancy were mainly total thyroidectomies (n = 24). The median number of days between diagnosis and surgical treatment was different between the groups with surgery during and after pregnancy (27 vs. 139 days, P < .001). Both maternal and neonatal outcomes were uncomplicated, regardless of gestational age during surgery. Conclusions: Well-differentiated thyroid carcinoma diagnosed during pregnancy has a favorable outcome for both mother and child. Surgical management during pregnancy has no negative impact on the pregnancy regardless of the trimester at the time of surgery. However, the potential negative effects of thyroid surgery early in pregnancy demand management of these patients in an experienced multidisciplinary team to provide the best possible care for these patients and their unborn babies.