Researchers have recently identified a link between low thyroid hormone levels in pregnancy and the child's inability to do mental maths & reduced height. (See daily mail article by searching 'daily mail pregnancy mental maths'.
I think it goes further than this, I think there's a link with low thyroid hormone levels in pregnancy and the child being on the autistic spectrum. My doses were all over the place when I was pregnant, and my levels were too - no account was taken of the time lag between dose increases and it correctly being reflected in blood levels.
I have a child on the autistic spectrum (aspergers) and I'm wondering how many other people have and what you think.