First of all, Iodine 131 treatment mainly plays a therapeutic role by destroying the thyroid gland, which may affect fertility, but the effect on fertility can often be minimized through reasonable intervention. 1. Short-term iodine 131 radiation after iodine 131 treatment may cause fetal growth and developmental disorders or malformations, so men and women of childbearing age are advised to use contraception within 6 months after iodine 131 treatment. 2. Abnormal thyroid function may occur after iodine 131 treatment, for example, after iodine 131 treatment in patients with hyperthyroidism, hypothyroidism may occur over time, which may affect fertility if not corrected in time. Therefore, iodine 131 treatment has an effect on fertility, but the effect on fertility can be avoided with reasonable evaluation and intervention, and it is recommended to follow the doctor’s instructions for treatment.