Your Baby's Life Support System

In This Article:

The role of the placenta

The placenta fulfills many essential roles that help sustain your pregnancy and enable your baby to grow and develop.

The exchange of substances

The placenta transports substances to and from your baby, acting as your baby's lungs, kidneys, and digestive system.

To obtain oxygen, the baby's blood cells grab oxygen molecules from your own hemoglobin (the oxygen-carrying subtance in blood). Fetal hemoglobin has a modified structure that makes it bind readily to oxygen. Your baby requires twice as much oxygen weight for weight as your own needs so the transfer of oxygen needs to be efficient. The placenta's enhanced blood supply, large surface area, and the characteristics of fetal hemoglobin all ensure the efficient transfer of oxygen from mother to baby.

As your hemoglobin gives up oxygen, it accepts carbon dioxide molecules. Your lungs breathe out air rich with the baby's carbon dioxide as well as your own and the cycle begins again.

To grow and develop your baby also needs amino acids, the building blocks for proteins, and minerals like calcium and iron and these all pass from your own circulation via the placenta to the baby.

Protecting your baby

The placenta protects your baby from infections and harmful substances. Since your baby hasn't encountered any external threats he doesn't yet make protective antibodies known as immunoglobulins that can identify threats, such as viruses or bacteria. Instead he is reliant on the transfer of immunoglobulins from your circulation via the placenta and into his circulation. This means that you are able to protect your baby in the uterus from illnesses such as chickenpox. After your baby is born, the immunoglobulins he acquired from you will eventually be lost, which means that later as a child he becomes susceptible to chickenpox.

Hormone production

The placenta produces hormones, such as estrogen and progesterone, that are vital to your baby's well-being and lead to many of the changes in your body during pregnancy.

Heat transfer

A baby's high metabolic rate generates heat. The placenta's big surface area and high blood flow disperses heat, controlling the baby's temperature.

How substances are exchanged in the placenta

Inside the placenta

The placenta contains a huge network of tiny projections called chorionic villi that branch out from a thin membrane, the chorion, and contain fetal blood vessels. The chorionic villi are bathed in maternal blood within the intervillous space. Each villus is only one or two cells thick, which allows the transfer of gases and nutrients between the mother and the baby, while ensuring that the two circulations never come into direct contact. Through the process of diffusion, oxygen and nutrients such as glucose, your baby's primary source of energy, from the mother pass into the fetal circulation, and waste products from the baby are picked up and carried away in the mother's bloodstream. The chorionic membrane also acts as a protective barrier, preventing many harmful substances and infections from reaching the baby.

Baby in utero

 Previous   1   2   Next 

excerpted from:

Excerpted from Pregnancy Day by Day.
Copyright © 2008 Dorling Kindersley Limited.
Buy this book now!

Pregnancy Day by Day

Tell us your due date to receive our daily newsletter and find out what is happening in this day of your pregnancy!

Already a member? Log-in here

Name of the Day

Quick Polls

Q: Do you enjoy being pregnant?

Yes-- I have that pregnant glow!

Heartburn, backaches, acne, and swelling -- what's to love?

I'm indifferent, but I can't wait for the end result.

View Results


Create Your Baby Registry with Target
Do you have everything you need to care for your new bundle of joy? Create your Target baby registry today!

Zika Virus Q&A: 4 Facts for Pregnant Women & Families
Zika virus is pretty scary, especially if you're pregnant or trying to conceive. Learn what steps to take to protect yourself from Zika virus, including travel restrictions and mosquito bite prevention.

Where Should Newborns Sleep? Comparing Bassinets, Cradles & More
Where will your bundle of joy sleep when she comes home? Get shopping and safety tips for choosing a bassinet, play yard, or other crib alternative that will fit in your bedroom, per AAP guidelines.

Top 100 Baby Names of 2016
Want to see which baby girl names and boy names are hot in the U.S. right now? Check out these lists from the S.S.A., and click on the names to see their meanings!

stay connected

Sign up for our free email newsletters and receive the latest advice and information on all things parenting.

Enter your email address to sign up or manage your account.

Facebook icon Facebook icon Follow Us on Pinterest

© 2000-2016  Sandbox Networks, Inc. All Rights Reserved.