Before Congress passed the Pregnancy Discrimination Act in 1978, nearly half of insurance policies did not include coverage of maternal care based on the argument that pregnancy was not an illness. That thinking, unfortunately, remains today when it comes to covering prescription birth control drugs and devices. A bill before Congress would change that and deserves support.

Approximately half (49 percent) of group health plans do not cover any female contraceptive, but 86 percent of the large group plans cover tubal ligation and 66 percent cover abortion. “What kind of perverse incentive is it when insurers make it more affordable for women to choose permanent sterilization or abortion over contraceptives?” Sen. Olympia Snowe asked before the Senate’s Committee on Labor and Human Relations this week. She and Sen. Harry Reid of Nevada have authored legislation called Equity in Prescription Insurance and Contraceptive Coverage Act.

Sen. Snowe asks an excellent question. The incentive should be in the opposite direction. For a minimal cost to beneficiaries — $1.43 per month, according to the Alan Guttmacher Institute — insurance companies could cover prescription birth control: the pill, IUDs, Norplant implants, diaphragms and injected Depo-Provera. A study from a couple of years ago suggests even more incentive. The American Journal of Public Health concluded the $300 annual cost for the pill was $3,000 less per woman per year than covering pregnancy-related costs.

Sen. Snowe raises a second important point. “I can’t think of anyone I know, no matter what their ideology, party or gender,” she said, “who doesn’t want to see the instances of abortion in this nation reduced.” The Guttmacher Institute concludes that the use of birth control lowers the likelihood of abortion by 85 percent, a truly beneficial — and, for insurers, cost-saving — idea. Some pro-life advocates view the use of the pill as a form of abortion and so won’t see the same benefit, but many others will.

Twenty years after maternity benefits were required by Congress to be covered, the Snowe-Reid bill would require that any insurance plan that already covers the cost of prescription drugs would also have to cover the cost of birth control. It is a logical step that Congress has plenty of reason to approve.