It would be best for your psychiatrist to speak to your ob-gyn as there are medications that have indications they cant be taken during pregnancy and some that can be be. However as they have a physician's only database that has all information on medications they could determine the appropriate decision with the specific clinical information.
Lithium is no good for pregnancy, but I took Seroquel during both of my pregnancies.
It is so important that you not take drugs that could harm your baby or cause it to have problems for the rest of its life! Some people have ECT during the pregnancy to taking care of depression and mania while not harming the baby. I am currently having ECT every 3 weeks. It is painless as you are put under anesthesia. Some people have a headache for a day or so. My pdoc has them give me something before the treatment that lasts for most of the day for the headache. ECT is safe and effective for 80% of the people who try it. The main side effect is some memory loss. I have very little memory loss and can remember after reminded about something.
There are certain drugs that are pregnancy category C, which means you can take them if you being stable is more important than a possible risk to the fetus. Lamictal is one. Talk to your psychiatrist ASAP about drug options and how you would deal without them. If you go completely off, you'll need close monitoring and should do all of the lifestyle change things you can to help, like exercising, eating healthily, having a consistent sleep schedule, getting lots of light, maybe taking fish oil (check that one with pharmacist first), etc. Take as good care of yourself as humanly possible to reduce any negative effects from mood disorders causing problems.