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
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.

Vasa Previa
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 are unknown.

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 bleed."

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 your physician.