Hi, Mr. Ranjan,
just a few facts :
1. U have mentioned TSH
value, only TSH 8.5 does not make the diagnosis certain if she is asymptomatic. only 8.5 TSH does not warrant urgent treatment. you must do free T4 and anti-TPO levels and lipid profile
2. maternal T4 is very important for the development of normal fetus in the 1st trimester. now she is in 3rd trimester, so nothing to bother now. and this level of TSH is unlikely to affect the baby. so dont bother so much.
finally no matter for worry. it may be subclinical hypothyroidism
, that may not require treatment.