Those who seek to justify abortion often try to minimize or deny the humanity of the embryo. In a recent online forum, for example, one participant wrote: "I became a human being at the point that my senses functioned as those of a human being. Before that I was just a mass of cells." Another followed up: "A pile of cells in a woman's uterus is not a human being. It lives off of and is part of that woman's body." The implication, of course, is that a woman ought to be able to do what she wants with her body, including the removal of any particular "pile of cells" that might pose a threat to her freedom.
Yet those cells are not posing a threat in the same way that cancerous tumor cells might. Instead, the cells of the embryo will upset her lifestyle by demanding that several months hence, she focus her attention on a bubbly, gurgling baby, and then a few years later, on a young child who needs an education, and then on a boisterous and strong-willed adolescent transitioning into adulthood, and then, possibly, on grandchildren, and so on. The cells of the embryo are not "just" a pile of cells, but an orchestration of living humanity known as a human being, marvelously complex, highly-ordered and structured, growing, expanding and developing in precise ways with each passing hour of intrauterine life.
Embryos, of course, do not spontaneously transform into human beings at the moment that their senses start to function, any more than they spontaneously transform into human beings at the moment that their kidneys start to purify waste, or their intestines start to process nourishment, or their heart starts to beat, or their limbs start to move, or their brain begins to function, each of which occurs at different time points along the embryo's normal path of growth and development.
The embryo's growth and development involves carefully choreographed biochemical steps and physiological changes that can be partially derailed by certain drugs. In the late 1950s and early 1960s, for example, the drug thalidomide was prescribed to pregnant women as a cure for morning sickness, but was quickly found to cause severe developmental defects and malformations in the newborn. Thalidomide's devastating effects resulted in the drug's being banned worldwide, after more than 10,000 children had been born with major thalidomide-related problems, including shortened or missing arms, hands extending from the shoulders, missing thumbs, and similar problems with the lower extremities, as well as abnormalities in the eyes, ears, heart, genitals, kidneys, and other organ systems.