Prohibits the abortion from being performed if the probable post-fertilization age of the unborn child is 20 weeks or greater, except where necessary to save the life of a pregnant woman whose life is endangered by a physical disorder, illness, or injury, excluding psychological or emotional conditions. Permits a physician to terminate a pregnancy under such exception only in the manner that provides the best opportunity for the unborn child to survive, unless that manner would pose a greater risk than other available methods would pose of the death or substantial and irreversible physical impairment of a major bodily function, excluding psychological or emotional conditions, of the pregnant woman.