When you hear the word "placenta," you probably think of the cord connecting you to your baby during his time in the womb. What you may not know is that it's actually an organ, doing a lot more than providing your baby with nourishment. The placenta is also a kind of padding, and maintains a unique environment in which your baby can develop and grow. The placenta forms from the same cells as the embryo and attaches itself to the inner wall of the uterus, growing as your baby grows and the volume of your amniotic fluid increases. When it's finished growing, it is circular and weighs about a pound; when the body expels it after the birth, many women are surprised at its size and weight.
Have you ever wondered why pregnant women have to be so careful about the kinds of drugs they take? The placenta is the reason. It links your blood supply with your baby's, transferring oxygen, nutrients, and anything that enters your bloodstream directly to her. It also works in reverse, removing waste from your baby's blood to yours so it can be disposed of. The placenta also produces hormones that play a role in triggering labor, and it helps protect your baby from infections and harmful substances.