|

The Umbilical Cord

The umbilical cord, which connects your baby to the placenta, contains three vessels: two arteries, which carry blood from the baby to the placenta, and one vein, which carries blood back to the baby. The blood in the arteries contains waste products, such as carbon dioxide, from the baby's metabolism. Carbon dioxide is transferred across the placenta to your bloodstream and then to your lungs, where it's breathed out. Oxygen is transported from red bloods cells in your circulation, across the placenta to the baby in the umbilical vein. In addition to oxygen, the umbilical vein transports nutrients from the placenta to your baby.

The vessels in the umbilical cord have a protective coating called Wharton's jelly, and the cord is coiled like a spring so that the baby is free to move around. The coiling pattern of the cord has usually established itself by week nine and is usually in a counterclockwise direction. However, the cord can coil later, and sometimes isn't established until 20 weeks. The baby's movements seem to encourage the cord to coil.

The cord is usually attached to the center of the placenta, although sometimes it's attached near the edge. Very occasionally, it divides into its separate vessels before finally entering the placenta. The cord is usually under 1 in (1-2 cm) in diameter and 23 in (60 cm) long, which is twice the length needed to ensure that there are no problems at delivery.

After delivery, the cord vessels close by themselves. The arteries close first, helped by their thicker muscular walls. This prevents blood loss to the placenta from your baby. The umbilical vein closes slightly later (starting at 15 seconds, but only completed by 3 or 4 minutes). This allows blood to continue to return to your baby during the first few minutes of life. As a result, many feel that a slight delay before clamping the cord can be beneficial to the baby. There are no nerves within the cord, so cutting the cord after delivery is a painless procedure for your baby.

Umbilical cord
This Doppler scan shows the blood vessels in the umbilical cord. Blood flows through a single vein (blue) and two arteries (red).

excerpted from:

Excerpted from Pregnancy Day by Day.
Copyright ©2009 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: Have you completed a birth plan?

17% 

Yes

50% 

No

33% 

What's a birth plan?

880 Total votes cast.

highlights

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!

Birth Control After Baby: 5 Options for Breastfeeding Moms
Find out which non-permanent birth control methods are safest for breastfeeding moms, and discuss your options with your doctor to find one that works for you and your partner.

12 Pregnancy Superfoods
Your body and growing baby have specific nutritional needs right now. Find out the pregnancy superfoods that will satisfy your prenatal cravings and nourish you and your baby.

Top 100 Baby Names of 2015
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

© 2000-2015  Sandbox Networks, Inc. All Rights Reserved.