I know that no one can answer this for sure until my biopsy, but my doctor told me that I have a nodule that is over 1 cm that wasn't there at my last ultrasound a year and a half ago and that is vascular (level 3) and has undefined borders. I'm thinking this sounds bad. This is all I know right now. I am going in for a needle aspiration on Feb. 22, and I am completely freaked out. I've had these done before, but she never told me that my nodules had cancerous characteristics. How freaked out should I be? I just had a baby 3 months ago and this is just throwing me for a loop…
I've read that pre-existing thyroid nodules can grow larger during pregnancy. I think it has something to do with the hormones or something. It didn't say that it had anything to do with chance of malignancy, though.
Do a search for "thyroid nodules and pregnancy" and you'll see the research.
I think it's still a good idea to get them checked out thoroughly. But I don't think it's anything to get freaked out over at this point. Regardless of what it is, you are on the right track to figuring it out. Focus on your baby right now and don't let this take away any of the joy of those first months (although I know it comes with a lot of stress, too).
If you have more questions or anything, feel free to re-post. Best of luck.