Puzzled about what your placenta actually does? Check out our guide to this essential part of your pregnancy.

pregnant woman
Credit: iStockphoto

You probably don't give a whole lot of thought to your placenta--even its common name, afterbirth, kind of gives the impression that it's an afterthought.

But in this whole growing-a-life-inside-of-you thing, the placenta's actually kind of a big deal. "I think the power of the placenta is extremely underrated," says Siobhan Kubesh, a certified midwife with ob-gyn North in Austin, Texas. "It's an amazing organ that forms and grows with your baby and completely sustains life."

This is no small feat--and no small organ. In the end, the placenta measures about 7 inches across and nearly 2 inches thick, and weighs in at about a pound's worth of blood and tissue. The placenta is a thick membrane, rich with blood vessels that help deliver nutrients and oxygen to your baby and take away waste products to keep your baby healthy.

The placenta also serves to protect your baby in utero--its massive membrane can help filter out things that can harm the baby, including dangerous microbes. "It's used to protect the baby from things that may be dangerous to its development, whether they're digested or in the environment," says Titi Otunla, a certified nurse midwife at Texas Children's Pavilion for Women in Houston.

The placenta also helps create that complex cocktail of hormones that starts coursing through your body when you become pregnant. (You can thank it for some of those wicked symptoms you've developed.) "The placenta generates pregnancy hormones which allow pregnancy to continue to develop normally, and eventually gives the signals for delivery and labor," says Marra Francis, M.D., an ob-gyn in Woodlands, Texas, and an author of the Mommy MD Guides. "Without a placenta, baby can't survive and pregnancy can't continue."

While your placenta does a pretty bang-up job of providing for your baby, you need to help protect the placenta. "Substances moms ingest could interfere with the placenta--including smoking, or taking drugs like cocaine or methamphetamines," Dr. Francis says. "The placenta can also be damaged if the mother has hypertension or diabetes. Injuries like falls can also damage the placenta, resulting in a loss of oxygen to your baby." But other than caring for your general health and avoiding activities that could injure your placenta (no more roller coasters for you!), you can't do much more to protect it. "In order to have a healthy placenta, you have to be healthy," Otluna says. "It's so important for making sure baby has enough oxygen and can grow. Everything the mom eats and does affects the baby and placenta."

The most incredible part of the placenta? It's a totally temporary part of your body. A few minutes after your baby is born, the placenta will be expelled in the afterbirth--and if you get pregnant again, your body will simply grow a whole new one. Pretty cool.

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