Ideally as your TSH level
was high even before pregnancy
should have been started at that time only.
Now, once started, you need to continue eltroxin, because with that dose, your TSH level has come in the normal range.
Also during pregnancy, many changes occur in the body systems, so you need to check TSH, free T3, and free T4 levels in each trimester and adjust the dose of eltroxin accordingly, as your requirement might change.
Hope this helps you.
Dr. Mrs. Sumeet Baheti