I second all of the above comments about chiropractic and pregnancy. I'm a chiropractor, and I am certified in Webster's and I do specialize in pregnancy. Not all DC's do, and not all are aware of the different issues that can come up during pregnancy and how to adjust their technique to the pregnant woman.
If you can't find someone on the ICPA website, I'd call those that are on your health plan and find out what technique they do. Asking questions about pregnant clients is helpful, but there are a lot of chiropractors that have many pregnant patients that still know nothing about pregnancy. Technique wise, I'd find someone that does Gonstead, SOT or Thompson. And I would find a doctor that specialized in one of those techniques, not just says that they do them. School wise, there are good and bad graduates from every school, so I wouldn't have that too high on my list of questions for the doctors.
Those are some good websites to start with for doctor searches. Also, as far as the whole insurance thing goes, I'll just say this. I don't accept insurance in my practice, but I only charge $25 for an adjustment (the first appointment is $50) and I do work with people if they have difficulty. I always tell my patients that I would rather see them get the care that is needed and pay me what they can when they can. It's generally not that difficult to find a chiropractor who will work with you regardless of your circumstances.
I hope this helps. Feel free to PM me if you have questions or if I can help you find a chiropractor who can help you. If you let me know where you are, I can see if I know anyone in the area that I can recommend. Sorry this ended up being such a long reply!