When Human Life Begins
American College of Pediatricians –March 2017
The predominance of human biological research confirms that human life begins at conception—fertilization.  At fertilization, the human being emerges as a whole, genetically distinct, individuated zygotic living human organism, a member of the species Homo sapiens, needing only the proper environment in order to grow and develop.
The difference between the individual in its adult stage and in its zygotic stage is one of form, not nature. This statement focuses on the scientific evidence of when an individual human life begins.