For group health benefit plans for groups other than small groups, no carrier may reject an individual for health plan coverage based upon preexisting conditions of the individual and no carrier may deny, exclude, or otherwise limit coverage for an individual’s preexisting health conditions; except that a carrier may impose a three-month benefit waiting period for preexisting conditions for which medical advice was given, or for which a health care provider recommended or provided treatment within three months before the effective date of coverage.