My insurance required us to tell them within the first trimester the times that I was pregnant or they would cover it. I am finding it hard to believe that insurance companies are able to turn you down for pre-existing condition. HIPPA law protects you from being turned down by insurance companies as well as protecting your privacy rights. I would definately check with a higher authority on this matter. If you can produce a credible coverge certificate(proof of the insurance that you had) then they can not turn you down, unless there are reason they are trying to turn you down that they have not told you about. Everyone is entitled to some form of insurance, thus the reason for the new laws.
InNeed I've never heard of having to tell an insurance company that you are going to become pregnant, it's not always planned. I agree that you should call your states insurance comm. who knows you may be able to get any out of pocket expenses returned to you. And make them cover your expenses now because they should have never cancelled you. Good luck..
Assuming that you live in the USA, if you have not already done so, then try calling your state's insurance commissioner's office. You need to know what your rights are regarding insurance coverage. I know that some insurance companies, or at least the representatives who deal directly with the public, are not always "forthright and honest" in explaining things to people. States have varying legislation, and in some states if the patient has no further indications of disease after a year (in some cases) then the insurance companies are to provide coverage.
You have my prayers for continued health, regardless of your insurance status!