Pre-existing conditions are ailments you had before your insurance policy became effective. This can be something you've lived with for a long time, or it could be a new diagnosis. Examples of common pre-existing conditions are diabetes, heart disease, cancer, asthma and pregnancy.
Some insurance policies exclude coverage for any and all pre-existing conditions, while others may only provide limited coverage. If a pre-existing condition isn't managed properly, treatment for it might not be covered under some policies. Make sure you understand the terms of your policy before buying it.