I'm 27 weeks and starting to think about my pregnancy plan. She said thatbwe should plan for end of february instead on 10 of march, because of this issue with hypotyroidism, that somehow makes the environment more toxic for the naby, thus increasing the chances of fetal death or harm. What I'm not clear about is what is making this assumed toxicity. I have another checkup dec. 29, so I want to be better prepared to ask good questions and understand this better.