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Umbilical cord: Evidence Based Document
Umbilical cord
Umbilical cord of a three-minute-old child. A
medical clamp has been applied.
Umbilical cord: In placental mammals, the umbilical cord (also called the navel string, birth
cord or funiculus umbilicalis) is a conduit between the developing embryo or fetus and the
placenta. During prenatal development, the umbilical cord is physiologically and genetically part
of the fetus and (in humans) normally contains two arteries (the umbilical arteries) and one vein
(the umbilical vein), buried within Wharton's jelly. The umbilical vein supplies the fetus with
oxygenated, nutrient-rich blood from the placenta. Conversely, the fetal heart pumps
deoxygenated, nutrient-depleted blood through the umbilical arteries back to the placenta.
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow
nutrient uptake, waste elimination, and gas exchange via the mother's blood supply, fights
against internal infection and produces hormones to support pregnancy. Placentas are a
defining characteristic of placental mammals, but are also found in some non-mammals with
varying levels of development.
There are a million and one things to think about before arriving
at your medical facility to deliver your baby. You may want to
think about your La Maze exercises or if all your favorite songs
are on your iPod. But, there is one thing you should think about
long before you leave your house with contractions.
Clamping
I believe clamping of the umbilical cord is a conversation all pre-parents should have with their
OBGYN early on during pregnancy. I speak about this to my patients because the outcomes of
the timing are so important.
Why? Because clamping of the umbilical cord not only has important implications for the
newborn infant, but because both mothers and infants can be affected positively or negatively.
That's why there is an ongoing debate between doctors and midwives regarding the benefits and
risks of the appropriate time to cut and clamp the umbilical cord. This argument generally refers
to clamping within the first 15 seconds of life or to delay clamping as long as one to three
minutes after birth.
Below is a summary of the literature regarding the pros and cons of immediate vs. delayed
clamping of the cord:
Advantages of delaying the clamping of the cord
1.
2.
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Reduces the incidence of anemia in the newborn.
Hemoglobin concentrations remain elevated for 2 to 4 months after birth.
Iron stores are increased for at least 6 months after birth.
Fewer infants need blood transfusion.
Studies of very low birth weight infants showed some protection against intraventricular
hemorrhage (bleeding into a baby’s brain), late onset infections, and prevention of motor
disability especially noted in male infants.
Facts: A delay of even 30 to 45 seconds in cord clamping, especially in preterm infants can
provide more blood volume and improve cardiovascular stability. By delaying even 30 seconds,
blood volume can increase by 8 to 24% (2–16 ml/kg at cesarean section or 10–28 ml/kg after
vaginal birth).
In preterm infants , this can be critical in increasing blood pressure, establishing higher
hemoglobin levels which can transport more oxygen to the tissues resulting in fewer days on a
ventilator, fewer transfusions, lower rates of intraventricular hemorrhage, fewer cases of
necrotizing enterocolitis (death of bowel tissue), and fewer cases of bronchopulmonary
dysplasia. (chronic lung disease of newborns).
The theory is that immediately after birth, the infant must increase the heart's output to the lungs
dramatically which requires adequate blood volume. If the cord is clamped too soon, not enough
volume is present so the body must "borrow" it from other areas of the body such as the brain
and the gastrointestinal tract and the lung itself resulting in lower blood flows in these areas with
potential damage occurring.
This damage can result in increased morbidity, mortality, and developmental delays. By delaying
the clamping of the cord, the additional amounts of blood can stabilize blood flow to the brain
and these vulnerable tissues, and increase the oxygen supply preventing infections and damage to
these organs.
Disadvantages of delayed clamping of the cord?
1. Polycythemia—hyperviscosity (large increase in packed red cell volume which can result
blood clots or possibly stroke)
2. Higher peak bilirubin concentrations requiring possible treatment with phototherapy
3. Increased risk of maternal blood loss while waiting for clamping of the cord.
4. Possible delay in resuscitation of the infant if needed (less than 10% of infants need
resuscitation) causing respiratory distress.
Facts: Studies have shown that although babies can have more packed blood volume from the
delay in clamping of the cord, no adverse consequences have resulted from this. In addition,
none of the infants studied had any increased risks of respiratory distress, or increased need for
intensive care or length of hospital stay. Some infants had an increase in serum bilirubin causing
jaundice requiring phototherapy at birth. There was no increased risk of maternal bleeding by
delaying the clamping of the cord.
How is blood volume in the infant changed by the delay and
position of the newborn after birth?
The total fetoplacental blood volume is about 120 ml/kg of fetal weight. The distribution of
blood between the fetus and the placenta is 2 to 1 which remains the same if the cord is clamped
immediately. Delayed cord clamping can result in an extra 20 to 40 ml of blood per kilogram of
body weight to the fetus which is also an extra 30 to 35 mg of iron.
By delaying 3 minutes, these higher infant blood volumes are obtained, especially if the infant is
held about 10 cm below the level of the placenta. By holding the infant even lower, at about 40
cm, the placenta hastens blood transfusion to the infant to within one minute. Without lowering
the infant, placental transfer of blood may fail to occur.
Analysis Questions
1) What is the umbilical cord and why is it important?
2) What is the Placenta and why is it important?
3) Sketch out a fetus, placenta,& uterine cavity (Don’t forget to label)
4) What is cord clamping and what is the great debate about cord clamping?
5) Create a T- chart with the pros and cons of clamping
6) After analyzing and discussing this document what is your opinion about cord clamping?
Would you be for it or against it….support your answer!!!!!!