The reasons why it is important to consider treatment carefully in any woman who may in the future have children is because the type of treatment may influence the outcome of a future pregnancy. The discussion and choices will revolve around the potential use of antithyroid drugs, radioiodine or thyroid surgery. There are many different factors which influence the final decision. For example if antithyroid drugs are chosen, which drug carbimazole/methimazole or PTU would be the most appropriate. PTU has traditionally been preferred due to its lower chances of foetal abnormality but there are also concerns due to its higher rate of liver toxicity. There are also clear reasons why you may not consider radioiodine therapy. This is mainly because it can worsen the anti-thyroid autoantibody status of the mother for a long period after therapy. Although the mother?s thyroid hormone levels may be well treated by radioiodine, the raised activity of the immune system has the potential to cross the placenta in a future pregnancy and affect the developing baby.