hormone binds to the body albumin
and displaces the T3 and T4 from the albumin and hence the TSH tends to go down. But you do not need to worry for TSH which is 0.03 as during pregnancy
lower TSH values are expected and it helps the baby's brain growth.
You check her TSH, T3 and T4 after 4 weeks and see if the TSH has gone further down and if T3 AND T4 have gone up then she'll need adjustments in the thyroxine
doses. So get back with her next reports for further assistance. Take care.