What is a pre-existing conditions clause and what is the effect of its inclusion in major medical expense plans?

A preexisting condition is often defined as a medical condition (i.e., an injury or illness) for which treatment was received or recommended during the 6 months prior to the insured’s effective date of coverage under a health plan.

A preexisting conditions clause excludes coverage for preexisting conditions for possibly as long as 12 months after the effective date of coverage, but can be shorter. Pregnancy is not a pre-existing condition.