Actually the placenta acts as a buffer between the foetus and body - otherwise the body would most likely reject the foetus. The foetus is a parasite - in the literal sense. It takes what it needs to survive from its host, i.e. the mother. The baby makes the placenta, however (the placenta develops because of the baby) and the baby gets all its nutrients and everything else it needs from the placenta. Therefore not strictly `feeding' off the mother at all. This is the only reason the body does not reject the developing foetus. It's pretty fascinating, actually.

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We've got rules and maps and guns in our backs, but we still can't just behave ourselves. Even if to save our own lives, we are a brutal kind. The Shins