Which Among Thyronorm And Eltroxin Better For Hypothyroidism During Pregnancy?

Hi im 28yr female nd 4 months pregnent with hypothyroidsm. I hav been taking eltroxin 100mcg since last 3 months of prgnency. But now my doctor suggested to take thyronorm 75#12.5 mcg daily for another 1 month. Now tsh is 0.24 and ft4 is 1.8. Changing the dose and medicine brand may cause any problem to featal development? Which one is better kindly answer me doctor..