clinical evident showed no increase in complications in subsequent pregnancy outcome

I presume you mean first trimester miscarriage. Therefore to know if women having radioactive iodine treatments for thyroid cancer have higher rates of miscarriage than normal, you would need a sample of women getting radioactive iodine during the first trimester. Do you have such a sample? Isnt radioactive iodine treatment rather rare in pregnancy? seems to be a rather isolated event, dont you think? Either the pregnancy is wanted and the woman would delay the treatment, or the pregnancy is not wanted and .....

Definately excess iodine has been shown to cause abortion/ miscarriage. I have been working on iodine excess and both steroidogenesis and reproductive functions both in animal models and epidemiologic studies has been shown to be affected under iodine excess.