I'm 12 days late with my period, which makes sense because we have been trying for a baby. But, exactly one week ago they told me I have an underactive thyroid and now I am really concerned and hoping that I am not! My TSH level is 10.3 (range should be between 1 and 5?) and my thyroid level is 8.9 (range should be 10.3 to 22). So they put me on 25 mcg of levythyroxine, which I have started taking. I have also tried three pregnancy tests (admittedly, all from the same box) which came back negative, but I'm really worried because I've read that you can harm your baby if it doesn't get anough thyroxine in the first 11 weeks - and for now, if I am pregnant, I would fall in that window. Any suggstions? I am going to try another test tomorrow morning...but is it normal to skip a period when you start on the levythyroxine? I was already late by 4 days when I started taking it. Really grateful for any advice, and thank you for the entries already on here - very reassuring to know I'm not alone.