I have Hashimotos (slow thyroid). Before the transfer she increased my dose to speed me up a drop..so, we did that one month before transfer..she checked me the day of transfer and when I got pg, she increased the dose again. I was monitored every three weeks during my pregnancy. I had a history of my thyroid going nuts when I was pregnant. Not sure every endo will do that but what I would suggest is that it your TSH should be under 2 (closer to one) when you begin your cycle. She kept mine under 1 during the entire pregnancy. My meds were changed four or five imes to meet the needs during the first trimester.
If you are in NYC, I can recommend this doc..she works with Cornell IVF patients.