The Law defines when a person begins. Personhood is attained when a living human organism develops a nervous system advanced enough to experience thought and emotion. At whatever stage of development that happens, there is a new person, and every person is entitled to all human rights, whatever their developmental stage or dependency.
The Law also guarantees every person sovereignty over their own body, and the Right to Physical Integrity, including freedom from any anatomical alteration they haven't consented to. And it says every person is responsible for keeping their offspring within what nature can sustainably provide.
Where rights appear to conflict, the Law ranks them, the more fundamental taking precedence (When Rights Conflict), and any disputed question is settled through Rationality, not by force or by majority.