Hi just had my baby 7 months ago - having hashimoto's and on thyroxine - my endocrinologist adjusted my thyroxine dosage higher during my pregnancy and kept my TSH range between 1-2 I would suggest that you see your Dr and discuss adjustment of your medication - i would ulternate days one day 50umg and the second day 100umg and that worked for me and kept my lewels well within normal range
All the best Good luck with your pregnancy
All I can tell you is, I was born w/out a thyroid gland (the only one in all of my family trees) to have this problem.
My children were born healthy and all their organs in place, including working thyroids.
I don't think hypo or hyper thyroid is inherited.
If a child is born with or in early stages of infancy begin to show symptoms of thyroid issues (Downe's syndrome/Mongoloid..etc) then don't bother looking up the family tree, get them to a Indocrinologist as soon as possible as it is a timely thing, and if not caught early can bring on problems that can be irreversible. I"m not a Dr. but have been t hrough he** with thyroid issues.