“Dr. Haig argues, a mother and her unborn child engage in an unconscious struggle over the nutrients she will provide it”….

“A fetus does not sit passively in its mother’s womb and wait to be fed. Its placenta aggressively sprouts blood vessels that invade its mother’s tissues to extract nutrients.

Meanwhile, Dr. Haig argued, natural selection should favor mothers who could restrain these incursions, and manage to have several surviving offspring carrying on their genes. He envisioned pregnancy as a tug of war. Each side pulls hard, and yet a flag tied to the middle of the rope barely moves.”

Kids as aggressive blood suckers. Sounds about right to me.