CordClamping.Info

Information about Research on Cord Clamping

Frequently Asked Questions

Why is this site needed?
Why delay cord clamping?
What happens at birth?
What is in my baby's cord blood?

What is the umbilical cord?
What are stem cells?

Q: Why is this site needed?
A: Birth is perhaps the most dramatic physiologic event any human will experience. How it is conducted may have effects that will last a lifetime.  Evidence is building that the current practice of immediate cord clamping is creating harm.  It has been associated with iron deficiency anemia in term infants that can affect a child’s ability to develop normally and achieve his full potential (Hutton 2007, Lozoff, Shafir 08).  For preterm infants, even a brief delay in cord clamping may protect an infant from bleeding in the brain and infection (sepsis) during the nursery stay (Rabe 2008, Mercer 06). In most hospitals, the practice of immediate cord clamping is a daily routine.  It began because people believed that the best thing for the infant was to give him quickly to the awaiting nurses and pediatricians for care.  However, long term effects on the infant of cutting the cord immediately were not studied until recently.  Many midwives advocate a delay in cord clamping but often this has been frowned upon in hospital settings (Mercer 00).
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Q: Why delay cord clamping?
A:  Immediate clamping of the umbilical cord is an intervention in the process of birth that was introduced without adequate study of its potential impact on short-term and long-term outcomes in infants and children. Immediate cord clamping can cause the baby to have a lower blood volume which may lead to poor circulation of the infant’s blood (capillary perfusion). Poor perfusion can result in inflammation and a lack of adequate blood volume to all organs (ischemia) just after the baby is born. Ischemia, or low blood flow, can result in a little to a great deal of damage to the newborn's organs, including the brain. We suspect that this damage may lead to increases in a variety of illnesses and developmental impairments in the child. We hope to conduct research to examine this hypothesis in the near future.
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Q: What happens at birth?
A:  When your baby is living inside you, it is called a fetus. As soon as it is born, he/she is called a newborn or a “neonate.” The fetus does not use his/her lungs to breath—Mom gives the baby all the oxygen he/she needs.  [He does have irregular breathing movements in his chest which help him strengthen his breathing muscles for later.]  At birth, the fetus/newborn experiences a huge physiologic transition as he weans from the placenta and begins to breathe using his newborn lungs.  The baby needs to establish effective gas transfer in the lung sacs (alveoli) and he needs red blood cells for delivery of oxygen from the air to essential organs.  Having a good neonatal blood volume helps a baby to do this.

Because the lungs were not used for breathing during fetal life, only 8% of blood pumped by the heart in any one minute (cardiac output) went to the fetual lungs.  Immediately after birth, he now needs 50% of his blood (cardiac output) to flow to and through the lungs as he establishes breathing for the first time. He needs access to his whole blood volume (through an unclamped umbilical cord).  Otherwise, he may have to “borrow” blood from his other organs resulting in low blood flow to a variety of organs.  Low blood flow can cause inflammation which can lead to subtle organ damage. This is where a problem can start if the cord is clamped immediately at the time of birth.
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Q: What is in my baby's cord blood?
A:  The fetal blood contains all the substances that adults have— plasma and red and white blood cells.  In addition, the fetal blood has many more stem cells than adult blood has.  Preterm babies blood have even more stem cells than those found in term babies’ blood.  Scientists have found that infants with delayed cord clamping of three minutes can obtain approximately 50% more red blood cells.(Yao 1969)  Red blood cells play a critical role in oxygen and carbon dioxide transport.  With immediate cord clamping, in a term infant, about 60 to 100 mL of the baby’s blood volume is will remain in the placenta.  The term baby will also lose a large amount of iron (about 30 to 50 mg) that he needs to make new blood cells over his first six months of life.

Both term and preterm infants have large amounts of stem cells circulating in the blood--these are also lost to the baby when the cord is clamped immediately.  Stem cells have a miraculous ability to heal. In animal models, they have been found to repair heart, brain, liver, lung, muscle, and endothelial cells lining blood vessels.  Immediate cord clamping robs an infant at term of millions of these miraculous cells at birth.  Blood banks to save the baby’s stem cells for the future have been established without any long term studies on the effects of removing them from an infant at birth.  Yet, in a study conducted on rats, injection of human cord blood stem cells within 24 hours after injury prevented cerebral palsy (Meier 2006).  That study, and other studies showing the healing powers of stem cells, demands that the safety of immediate cord clamping at birth be studied with long term follow up of the children to at least age three.
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Q:  What is the umbilical cord?
A:
The umbilical cord is a long tube-like structure that forms even before the fetus (baby) forms (see Figure 1).  It has two arteries and one large vein which carry blood back and forth between the placenta and the fetus.  The fetus’ (baby’s) heart pumps the blood between his/her body and the placenta.  The mother’s blood supplies oxygen and nourishment and takes away waste products to keep the fetus healthy (their blood does not mix—the exchange occurs across a very thin membrane).

umbilical cord

 Figure 1: Fetal Circulation

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Q: What are stem cells?
A:  When we say “stem cells” on this web site, we are referring to the stem cells found in large numbers in the blood of fetuses and infants.  These are often referred to as “hematopoietic” or blood-making stem cells.  Never again in one’s life will there be such a high number of circulating stem cells.  We now know that these cells can specialize into multiple types of cells in the body as needed and can help heal the body.  (see http://stemcells.nih.gov).

There are several important properties of stem cells.  They can “self-renew.” This means that when they divide as all of our cells do, they can make one exact replica of themselves along with a new type of cell. This is important to keep stems cells available in the body for maintenance throughout our lifetime.  They can also “differentiate” or make specialized cells such as heart or brain cells.  The term for this is “pluripotent” meaning that they can become many different kinds of cells as the body needs.

We are on the edge of what we know about stem cells. The research on stem cells is in its infancy and many scientists and others are very excited about their potential.  Every day, there is a new article in the paper about experiments using stem cells to treat everything from cerebral palsy to Alzheimer’s disease.  Stem cells are difficult to study. They do not behave in the research laboratory as they do in the human body.  In your body, if you have an area of inflammation (swelling, irritation, etc), the lining of the blood vessels in that area release cytokines (messenger proteins).  It is believed that these cytokines signal the stem cells to come to that area to help heal and repair the site.  This process is called “homing” – the stem cells are called "home" to the damaged area in the body.  The fact that it is hard for scientists to make the exact mixture of cytokines to "home" the stem cells has hampered research.

We think that a newborn should obtain his or her full number of available stem cells at birth.  This can be accomplished by delaying the cord clamping or even by milking the cord at birth.  If the labor and birth is especially traumatic for the infant, the stem cells are available to help with healing.  One recent German experiment using young rats demonstrates this very well.

Meier and colleagues (2006) demonstrated that administration of human cord blood to rats in whom neurological damage had been created was useful in preventing the development of cerebral palsy. They cut the rat pup’s carotid artery on one side creating a progressive inflammatory process.  This led to death of neurons on one side of the rat’s brain and resulted in spastic paresis (cerebral palsy). In one half of the damaged rats, they injected human umbilical cord stem cells into the abdomen within 24 hours after the injury.  The rats who were given the human cord blood stem cells, did not develop spastic paresis.  The rats who were damaged and got no treatment or who got the treatment after 24 hours, developed cerebral palsy.   Upon histologic (microscopic) examination of the rat brains at 21 days after the injury, Meier et al (2006) found that the human umbilical cord blood stem cells had crossed the blood-brain barrier and had surrounded and infiltrated the damaged areas of the injured rats’ brains.  These cells appeared to provide scaffolding for repair. The scientists did not find any stem cells in the uninjured side of the brain.  This suggests that factors (probably cytokines) from the damage areas signaled the stem cells [33]. Human infants most likely to develop cerebral palsy rarely obtain their full allotment of stem cells at birth—usually the cord is cut right away.  We estimate that when the cord is clamped right after birth, infants lose millions stem cells. Might these stem cells play a role in healing our infants’ brains? We believe that this animal study, along with other studies on the healing powers of stem cells, demands that the safety of immediate cord clamping at birth be studied and must include long term follow up of children to the age of at least three years of age. 

When an infant receives more blood volume at birth, he/she should also receive a greater allotment of hematopoietic stem cells. When cells are collected for freezing and storing, fewer stem cells are available as the processing reduces the stem cell count by 33%. Male infants have a higher content of stem cells collected even when corrected for birth weight. Thus immediate cord clamping may be more damaging for male infants. In one of our studies, we found a significant advantage of less intraventricular hemorrhage (bleeding in the brain) and less sepsis (infection) in preterm male infants with a brief delay in cord clamping (Mercer 2006).
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(Last updated: 02/07/2009)