Background: Thyroid cancer (TC) is one of the most common carcinomas in young women. Concerns have been raised regarding the impact of the disease and its treatment on reproductive function. The aim of the study was to investigate the association of TC diagnosis and radioactive iodine (RAI) treatment on infertility and pregnancy rates in women. Methods: The comprehensive computerized database of a health management organization in Israel was screened for all female patients who were diagnosed with TC at age ≤40 years in 2000-2020. Rates of infertility (based on a documented diagnosis or purchase of fertility medications in the patient files) and pregnancy were compared with healthy age-matched controls. Results: The cohort included 1164 patients with TC (median age at diagnosis 31.6 years; interquartile range [IQR]: 26.7-35.4) and 5030 controls, followed for a median period of 10 years (IQR: 5.0-15.0). The infertility rate was higher in the TC group than in the control group (23.9% vs. 20.4%, p = 0.008). Still, the postdiagnosis/referent date pregnancy rates were comparable in the whole cohort (46.9/47.7%, p = 0.625) and across all age quartiles. The median time to the first pregnancy postdiagnosis/referent date was longer in TC patients than in controls (37 vs. 31 months, p < 0.001). Within the TC group, women who received repeated radioactive iodine treatment (n = 611, 52.5%) had comparable rates of infertility and pregnancy as those who did not. However, their time to the first postdiagnosis pregnancy was longer (median 45 vs. 29 months, p = 0.020). Conclusions: Our study provides reassuring evidence about the reproductive characteristics of women treated for TC. Pregnancy rates in TC survivors were comparable with controls. However, a higher infertility rate and a longer time to conceive were observed in the TC group compared with the control group. These findings were consistent in women who received single or repeated RAI treatments.
Keywords: infertility; pregnancy; thyroid cancer.