Hyperthyroidism during pregnancy

Hello doctor,
I am 31 year old pregnant with second child. Now I am 13 weeks pregnant.During my 3rd month visit only my doctor asked me to do the boold test and thyroid test for the first time. I had my test on 26th Feb 2011.Today we showed the result to the doctor and she told that TSH level is little bit high. It is showing 6.85. From tomorrow onwards i am staring my medication for that.

I want to know is there any risk of brain problem of baby? will it cause to lower IQ or anyother problem for my child? Since I didn't check my blood during my first 3 months of pregnancy, will it affect the  foetus? As I read in one article that during first 3 months the baby will use mothers thyroid related hormones...Will there be any problem with my kid?  
                                Please answer docotor.. I m really worried abt my baby. I would appreciate it.
                                                                                                        
                                                                                                                         thank you.