Are insurance plans required to cover infertility services? why or why not

I don't think that infertility services should be required for coverage on insurance plans, but I do think people should have options to provide themselves with that coverage for an extra premium.  A woman would have to elect the additional premium by a certain age (determined by the insurance company), and so long as those premiums are up to date then infertility treatment could be covered.  It might actually be a moneymaker for the insurance companies, and provide a sense of security to people who know that having a family will be a priority they will fight for financially if they have to.