As a matter of fact, the fact we consider babies human is a progressive evolution in human history. In ancient Greece for example, children were considered property of their father till the age of puberty, who could dispose of them (including of their life) the way he wishes. A father could kill his son without consequences
Realistically they are not a human just legally they are.
It's hard to say when human life begins but we seem to settle on treating it as after they are born.
But this is nonsense in any scientific sense.