Some health insurance companies may not want to sell you a health insurance policy if you have a pre existing condition prior to signing up with them.
But some health insurance such as Blue Cross will cover you with a pre existing condition and they cannot deny you coverage just because you have a pre existing condition.
Pre existing health conditions for health insurance are things such as epilepsy, cancer, diabetes, lupus, sleep apnea etc.
There are some health insurance companies that will approve you and sell you health insurance with pre existing conditions.
Firstfamilyinsurance.com will usually approve you for health insurance coverage with pre existing conditions but it's a good idea to find other health insurance including Obamacare health insurance that can cover you with pre existing conditions.