|

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

stay connected

highlights

3 Fun Thanksgiving Games for Kids
Looking for some great Thanksgiving games to play with your kids? Print our free Pin the Feathers on the Turkey game, Pin the Hat on the Pilgrim game, and Thanksgiving Parade Bingo game for loads of laughs this Turkey Day!

Kindergarten Readiness App Wins Gold
Our Kindergarten Readiness app won the Gold Award of Excellence in the educational category at the 2014 Communicator Awards. This valuable checklist comes with games and activities to help your child practice the essential skills she needs for kindergarten. Download the Kindergarten Readiness app today!

Top Family Movies in Theaters for the Holidays
Taking the kids to the movies is a special family treat for the holidays! Don't miss 2014's best family films in theaters from Thanksgiving through Christmas.

Find Today's Newest & Best Children's Books!
Looking for newly released books for your child? Try our new Book Finder tool to search for new books by age, type, and theme, and create reading lists for kids!

© 2000-2014 Pearson Education, Inc. All Rights Reserved.