Welcome back to 6th grade science. I think you misunderstood the point.
A + B = AB. You’re just putting two ingredients together. Nothing more. There’s no special thing that happens that suddenly gives you life. There’s no magical aura that surrounds my vagina and lifts me to the sky when I get pregnant. All that “fetus” is, is a couple of chemicals thrown together now performing an action encoded in some of it’s chemicals. It’s not a life. It’s not something new. It’s not A + B = C. It’s a sperm cell and an egg cell and a couple duplicates. Stop treating it like it’s anything more.