Week of June 27, 2006
Inside the Lifeline
An Article From iParenting Media
By Jennifer Lacey
The umbilical cord acts as your developing baby's lifeline, working constantly
by carrying essential nutrients and oxygen that your little one needs for continued
growth and development. With advances in ultrasound technology, umbilical cord
complications are frequently diagnosed during pregnancy.
Several unusual complications can affect the umbilical cord. It can be formed
either too short or long, become knotted during the course of a pregnancy or feature
other complications that can be potentially life-threatening to both mother and
child if left undiagnosed.
Just the Facts
The umbilical cord begins to form very early in pregnancy, approximately five
weeks after conception, and its growth becomes very progressive. "The mean
length at term is 55 to 65 centimeters, though there can be a lot of variation,
with some evidence that fetuses that move a lot have longer cords and those whose
movements may be decreased by low amniotic fluid, for example, are shorter,"
explains Dr. Sarah H. Poggi, a perinatologist at the Brock Family Perinatal Diagnostic
Center at the Inova Alexandria Hospital in Alexandria, Va.
Inside the umbilical cord, there are two arteries and one vein. The vein carries
oxygenated blood from the placenta to the baby, and the two arteries bring the
deoxygenated blood from the baby to the placenta. The three blood vessels are
protected with a cushioned gelatin-like tissue called Wharton's jelly.
Single Umbilical Artery
According to the March of Dimes, single umbilical cord arteries occur in about
one percent of single pregnancies and about five percent of pregnancies of two
or more babies. The exact causes of this condition remain unknown and can only
be diagnosed via ultrasound. When ultrasound discovers this condition, and if
the developing baby appears to have no other health complications, the baby is
likely to be born healthy.
However, recent studies have suggested that 25 percent of babies diagnosed with
single umbilical cord arteries in the United States may be diagnosed with other
birth defects such as cleft palates. "It is associated with renal and cardiac
anomalies in the baby [and] chromosomal abnormalities and can also be associated
with fetal growth restriction and possibly fetal distress," says Dr. Poggi.
"It can also be an incidental finding in an otherwise normal pregnancy. We
follow these patients very carefully, but it is not an uncommon finding and most
often the babies do well, particularly if it is an isolated finding."
According to Dr. Poggi, expectant women carrying a baby with a single umbilical
cord artery will undergo extensive prenatal testing, including a detailed anatomic
survey, fetal echocardiogram or amniocentesis, which is particularly performed
if there are other factors present, such as if the mother is older. "We will
also conduct serial scans for fetal growth and fetal non-stress tests towards
the end of the pregnancy," says Dr. Poggi.
Cord prolapse occurs when the developing baby's umbilical cord falls into the
birth canal ahead of its head or other parts of its body. "When the baby
is a footling breech, there may be only a foot or nothing much in the pelvis,
and so if the cervix opens up and the membranes rupture, the cord can slip by,"
says Dr. Poggi. Cord prolapse is a very serious condition, and it is potentially
harmful to the baby. The baby's supply of both oxygen and blood will be cut off
when the umbilical cord is found to be either compressed or squeezed.
Although uncommon, Vasa previa occurs in one per every 2,000 to 3,000 births.
Just as with single umbilical cord arteries, the exact causes of this condition
What is known is that when this complication occurs, it is extremely life threatening
to the survival of the unborn baby. "Vasa previa occurs when the fetal vessels
running in the membranes that will give rise to the cord happen to be directly
overlying the cervix," says Dr. Poggi. "Should the cervix dilate and
the membranes rupture, the blood vessels will also be torn and the fetus will
According to the March of Dimes, even in cases where the baby's blood vessels
fail to rupture the baby is at severe risk to suffer from lack of oxygen caused
by the pressure on the blood vessels. Vasa previa is usually diagnosed via ultrasound,
though it may be occasionally felt during palpation in an examination. Cesarean
birth is the normal preferred type of delivery for women diagnosed with vasa previa
upon confirmation of the baby's fetal lung maturation.
While many of these conditions are rare, it is important for pregnant women to
understand the significance of their baby's lifeline, the umbilical cord. If you
have any questions or concerns about the umbilical cord and your pregnancy, consult