The old, uninformed notions that unborn and newborn babies could not feel pain are refuted by a growing body of scientific evidence. The published scientific literature shows that unborn babies can experience pain at 20 weeks gestational age (20 weeks LMP, since Last Menstrual Period, the fetal age estimate used by most obstetricians) or earlier. There are two common methods used to measure the age of an unborn baby: Probable post-fertilization age (PPF, used by embryologists) measures the age of the unborn baby from the actual date of conception, while gestational age measures from the first day of the mother’s last menstrual period (LMP, approx. two weeks before conception). Medical practitioners have been using the latter method as standard medical practice for decades, and for the purpose of this paper ages refer to gestational age unless otherwise indicated.