The joining of a man's sperm with a woman's egg, a zygote is formed, thus, the very first stage of a human being's life. All information is present at this stage for the human person to grow into an embryo, fetus, infant, toddler, child, teenager, and adult. There are not separate distinctions of the human species during its first stages of growth.
The act of terminating the life of an offspring before it is developed enough to leave the womb. Wouldn't be such a big issue if the vast majority of people who undergo it didn't make the stupid decision of fucking without thinking ahead about the consequences, such as getting pregnant as a result.