Kim HO, et al. - In this population-based cohort study of 111,459 South Korean women of childbearing age (20-49 years) who underwent thyroidectomy for differentiated thyroid carcinoma between January 1, 2008, and December 31, 2015, experts examined whether radioactive iodine treatment (RAIT) was related to rises in adverse pregnancy outcomes among South Korean women who received RAIT following thyroidectomy for thyroid cancer and assessed the relevant interval between RAIT and conception. In contrast with individuals who underwent surgery followed by RAIT, among patients who underwent surgery alone were, the rates of abortion, preterm delivery, and congenital malformation were 32.1% vs 30.7%, 12.9% vs 12.8%, and 9.0% vs 8.9%, respectively. A subgroup analysis based on the interval between RAIT and conception designated congenital malformation rates of 13.3%, 7.9%, 8.3%, and 9.6% for the interval of 0 to 5 months, 6 to 11 months, 12 to 23 months, and 24 months or more, respectively. Based on the interval between RAIT and conception, the abortion rates for the interval of 0 to 5 months, 6 to 11 months, 12 to 23 months, and 24 months or more were 60.6%, 30.1%, 27.4%, and, 31.9%. Hence, in these large-scale real-world data designate that when conception occurs 6 months or more following treatment, receipt of RAIT prior to pregnancy does not seem to be related to rises in adverse pregnancy outcomes.