Shannon,
Congradulations!!! From what I’ve read thyroid replacement pills (except for the fillers put in to make it a “pill”) are chemically identical to T4. As long as your levels are appropriate there should be no adverse impact on the baby. In fact, from what I’ve read, this is the safest treatment for you to be on in terms of your baby’s health. But you may need to be monitored more closely while you are pregnant to make sure you stay in the proper range. Pregnancy brings a whole bunch of hormonal changes, which might (I don’t know, but I’d ask)affect your needs for T4. Check with your doctor.