Calm down, I have hypothyroidism, basically a very low functioning thyroid. They will probably try to regulate your thyroid and have you do regular blood work to check that your levels are ok during your whole pregnancy. Many women have this, don't worry. The baby and yourself will be ok. It's only dangerous if you go around untreated.
this - I have hypothyroidism also - its very easily treated with medication - some women only get it during pregnancy so it may go away after you have the baby but until then take your meds and you will be fine!