Do you take any Thyroid meds right now? When the TSH is low, the Thyroid hormon is high, wich is what happens naturally when anyone is pregnant, though I would consult with your OB to make sure that your levels are appropriate.
I don't have a thyroid, so I have to take synthroid every day, and since I am a thyroid cancer survivor, they already had me on a pretty high dose, so my TSH is low. This helos prevent the cancer from growing back. I am seeing an endocrinologist and he will be monitoring my Thyroid levels closely during pregnancy in case I need to make any adjustments.