Hello doctor , i am 31 yrs old . today i have completed 17 weeks of pregnancy. unfortunately i did thyroid blood test on 10th jan 2013. (at 16 week of pregnancy). T3 (total) by CLIA, serum is 158.83 ng/dl, T4 is 12.70 ug/dl , TSH (ultrasensitive) serum by CLIA is 4.84 . my doctor advise me to start the thyronorm 25 mcg tab . act i am bit worried due to late start of treatment n secondly can this tablet increases the iodine level? how frequently i should check the TSH level ? i read that @ 10 to 12 weeks the baby thyroid begins to function on its own . if i started thyroid medication late would it affect on my baby IQ development / brain development? pls suggest .