Here is an excellent essay by Robert George entitled “Are Human Embryos Human Beings? Here is the conclusion:
“The pro-life view depends on an undisputed scientific fact plus a moral principle that explains and vindicates the worth of infants and the cognitively impaired, and affirms the profound, inherent, and equal dignity of every member of the hurnan family. The defense of elective abortion depends on a moral view that must deny these points, a biological view that contradicts science, or both.”