Thyroid levels in the First Trimester

Does anyone know what normal thyroid levels should be during the first trimester? I'm currently 10 weeks pregnant(and 6months postpartum). My pcp ran bloodwork during my yearly physical and said my thyroid levels were low and .29. He retested them again a week later and said they lowered even lower to .21 and he stated that he was uncomfortable treating a pregnant women with any issues. So I contacted my OB to speak with them, still waiting on a call back. Was just curious as to see if anyone else may of had this issue or could explain a little more to me. Never had issues with thyroid before this.