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A Cord of Three Strands...

Posted Apr 26 2010 3:45pm
The umbilical cord is an amazing object!

Often disregarded at birth, the most notoriety that it receives is when someone proudly exclaims "I cut the cord"!

There is so much more value to the umbilical cord than that, though, both in utero and after birth.

Normally, an umbilical cord has two arteries and one vein and, at term, is around 22-24 inches long. These are all wrapped up in a beautifully plump, purple, rich cord of three. Surrounding, insulating, and protecting everything is a substance called Wharton's Jelly . The arteries return deoxygenated, nutrient-depleted blood from babe to the placenta, where it will be reoxygenated and replenished with vital nutrients to be recirculated through the one vein back to babe again.

Wharton's Jelly is a substance that, when exposed to extreme changes in temperature, begins to expand and, as a result, occludes and collapses the vein and arteries... physiologically clamping the cord within an average of 5-20 minutes after birth. Wharton's Jelly contains a great many types of stem cells.

The umbilical cord is attached to the placenta 'on the maternal side'. The placenta (loosely translated as cake) is another amazing organ that allows for nutrient uptake, waste elimination and gas exchange via the mother's blood supply, which is then transferred to the fetal circulatory system via villi; thus, the maternal and fetal circulatory systems do not meld.

The umbilical cord is attached, on the fetal side, through the umbilicus (this will, after birth, become the navel). Within babe, while in utero, the umbilical vein continues on to the transverse fissure of the liver, where it splits. One of the two branches joins with a vein that carries blood directly into the liver. The other branch (ductus venosus) directs about 80% of the incoming blood to the left hepatic vein into the inferior vena cava, which carries blood towards the heart.

After birth, the umbilical vein and ductus venosus close up inside the newborn, becoming the round ligament of the liver and the ligamentum venosum. Part of each umbilical artery closes up while the remaining sections continue to work as part of the circulatory system.

Variations
Some of the variations that can occur with an umbilical cord include (but are not limited to)
  • Nuchal Cords - nuchal (neck) cords simply mean that the cord is wrapped around the neck. This occurs in about 25% of births. Most babies have no problems when born with the incidence of nuchal cord. The most common indicator of a nuchal cord is when babies heart rate (fetal heart tones or FHT) decrease during contractions, only to come back up after contractions. Rarely does this mean that a cesarean is indicated.
  • Single Umbilical Artery - This is occurs when an umbilical cord develops with only one artery, instead of two. Single umbilical arteries occur in about 1% of singleton and 5% of multiple pregnancies. Studies show that babies with single umbilical artery have an increased risk for birth defects. These birth defects can include heart, central nervous system and urinary-tract defects. Single umbilical artery in and of itself, though, does not mean that a baby will have a birth defect.
  • Knots - some knots occur when baby moves around in utero, others occur when a nuchal cord loops off of baby and into a knot. This occurs in about 1% of babies.
  • Cysts - the cysts are out-pockets that form on the cord. There are two types of cysts: true cysts (lined with cells and contain remnants of early embryonic material) and false cysts (fluid filled sacs that can be related to swelling of the Wharton's Jelly). Both types are sometimes associated with chromosomal or abdomenal defects. Cysts occur in about 3% of births.
To Clamp or Not To Clamp
There are good arguments that should be considered when deciding whether to immediately clamp and cut the cord or delay the procedure. A great discussion can be found here . An additional MUST READ can be found here ! You will find, for better or worse, what my stance is on the issue of cord clamping by reading the information below.

"The placental blood normally belongs to the infant, and his/her failure to get this blood is equivalent to submitting the newborn to a severe hemorrhage at birth."
The newborn receives approximately 80-100cc of blood from the placenta within the first 3-5 minutes after birth. This additional blood flow opens the lungs and 'jump starts' the intestines and kidneys, preparing them for digestion and elimination.

When a newborn's cord is quickly clamped and cut, before the bolus of oxygenated blood is adequately transfused, it creates a crisis situation in some/many situations. Instead of supplying 80-100ccs of blood to the newborns intestines, survival dictates that the blood already within the newborn be directed to the heart, lungs, and brain to preserve life. Loss of needed blood results in some pathological symptoms of shock in the newborn - hypovolemia and/or hypoxia.
"Normal blood volume is not produced by a cord clamp ... Many neonatal morbidities such as the hyperviscosity syndrome, infant respiratory distress syndrome, anemia, and hypovolemia correlate with early clamping. To avoid injury in all deliveries, especially those of neonates at risk, the cord should not be clamped until placental transfusion is complete." - George M. Morley
If the cord is cut before the baby has a chance to take a few breaths in his own time, the transition to breathing will be in fear, panic, and distress. To force a newborn to breathe independent of the bodies timing (i.e. physiological clamping) is to add risk that the baby/newborn body may not be ready. In other words, creating a crisis where the child must immediately breathe - rather than allowing adequate and safe time. As long as the cord is pulsing, the newborn is receiving oxygen - why create an emergent situation?
"Early cord clamping may impede a successful transition and contribute to hypovolemic and hypoxic damage in vulnerable newborns." - Mercer JS and Skovgaard RL.
Some doctors argue that waiting to clamp and cut will put undue stress on the newborn and create complications like shock, jaundice, or other newborn complications. But, in fact, in 1993, a study by "Kinmond et al...found no increased jaundice, plethora, hyperviscosity, or polycythemia using this method. Yet fear of late clamping persists because physicians have been conditioned to believe that these complications are caused by placental over-transfusion. Cord stripping (allowing the baby to retrieve its own blood supply) has become tantamount to malpractice."

Finally, I leave you with this: who claims right to that super-rich oxygenated blood? Of course, it is the baby's right to claim.

ReferencesWalsh, SZ, Maternal effects of early and late clamping of the umbilical cord, Lancet, May 11, 1968
Anne Frye, CPM, Holistic Midwifery: A Comprehensive Textbook for Midwives in Homebirth Practice, Labrys Press, 1998
George M. Morley, MB., CH. B "Cord Closure: Can Hasty Clamping Injure the Newborn?", OBG Management - July 1998
Gupta R, Ramji S. Effect of delayed cord clamping on iron stores in infants born to anemic mothers: a randomized controlled trial. Indian Pediatr 2002 Feb;39(2):130-5
Mercer JS and Skovgaard RL., Neonatal Transitional Physiology: A New Paradigm, J Perinat Neonat Nurs March 2002; 15:56-75.
Mercer, J, Bewley, S, Could early cord clamping harm neonatal stabilisation, Lancet, May 9, 2009
Dr. Sarah Buckley, Gentle Birth, Gentle Mothering, One Moon Press, 2005
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