Radioactive iodine and pregnancy

Answer 1

The I-131 isotope is most commonly used to treat thyroid conditions, including but not limited to thyroid cancer. It is used to either reduce thyroid function by partly destroying the thyroid, or to obliterate remaining thyroid tissue (including cancerous cells). It can damage the developing thyroid of a fetus, and should never be given to pregnant women. It has similar effects on newborns, and thus women who are breastfeeding should stop before treatment, although they should be able to nurse future children without consequence. Because the ovaries can be effected by radioactive iodine, women are encouraged to wait at least six months (some resources suggest waiting a year) before attempting to conceive. Studies have not shown any immediate risk to pregnancies or to babies conceived four to six months after the dose was given, but further follow-up is required to be certain that the children born of these pregnancies will not experience complications later in life.