Lets talk about iodine.
Have you two been using iodized salt for years. Confirm label on salt package.
If not continued iodized salt, she/you need supplemental iodine to get out of the hole. Try 0.5 1.0 mg/day for two weeks then pregnancy RDA after.
Prenatal vitamins should have the higher RDA.
RDA's for iodine are increased during pregnancy for a good reason. Baby's thyroid needs iodine too.
Women store iodine in breast tissue. Assumed to be for lactation for the baby.
Check her oral body temperatures as per the thyroid basics sticky. These can be used to guide iodine replenishment or thyroid med dosing.
Note that some do not convert T4 medications to T3 very well and need a T4+T3 product like Armour Thyroid.
This is critical to fetal development.
TSH too high. fT3 fT4 are well below mid-range.
Does she get cold easily? now? before pregnancy?
Thyroid enlarged, sore, asymmetrical or lumpy.
Outer eyebrows sparse [if not plucked]
Essential fatty acids, flax seed oil/meal, nut and fish oil are associated with higher IQ's in children.