Your wife is suffering from hypothyroidism
and this type of picture usually gets uncovered during pregnancy
, when there is more demand for thyroid hormones. It is good that she has been started on thyrox- 75...this will help in correcting her thyroid profile and will only benefit the fetus (and not harm it). Right amounts of thyroid hormone in the mother is required for the normal development of the brain and nervous system of the fetus.
You should advise her to take her medication regularly.