Think of it in machine terms. Preliminary assembly puts the constructing unit - the mother - on reduced service for, on average, one third of the gestational period, while consuming even more resources than she had before. Once born, a human is not functional; primary assembly requires, on average, seven years, during which the child is literally an energy sink, consuming time, attention, and food without any return except dung. To achieve full physical function requires, on average, about sixteen years. And this leaves aside questions of training and education, emotional stability, and disciplined intellect necessary for self-direction, all of which require even more time and energy to inculcate. If people had any idea just how expensive a human being is, they’d take better care of themselves.