Well then their decision is within their knowledge and it makes sense but you should have them talk to your psychiatrist about what could replace it. This is the list we have linked of all mood stabilizers:
http://www.psycheducation.org/depression/meds/moodstabilizers.htm
Perhaps ask the OB-GYN which ones would not cause any harm to the fetus in development. Then the psychiatrist could decide which out of them would be appropriate for you.
The OB-GYN I talked to today told me to stop taking the Lamictal until I got in touch with my doctor because it can be harmful for the baby.
That's a good question but one you'll have to ask your psychiatrist and doctor specifically. Your psychiatrist can find out specifically which ones you could take and your doctor could approve them as well as that's a specific medical question. It does list whether a medication can be taken in pregnancy on the medication website if you go to the full prescription listing. But ultimately a doctor has to make that decision. It is difficult to go off certain medications you know are helping you as what its treating will return and the hormonal changes in pregnancy can worsen things. Any psychiatrist should be able to give you a proper answer by going through their online database for medications which only clinicians can access.