October 21, 2013. Marta Wegorzewska, PhD candidate, in collaboration with Dr. Seth Bokser, MD. Edited by Dr. Seth Bokser, MD; Dr. Angie Jelin, MD; Dr. Yao Sun, MD; Dr. Tracey McLean, MD.
The crowning of the Jacob’s head sparks excitement and anticipation. Family members are there to support the mother and celebrate the arrival of the newborn. The obstetrician announces the baby is coming and coaches the mother through every last contraction, encouraging her through the final stage of labor. The next minute, the first minute of the newborn’s life, happens fast. The umbilical cord (cord) is clamped in two places and cut between the clamps. Jacob’s cries come instantly and the entire room breathes a sigh of relief. He is cleaned and wrapped in towels for warmth. The healthy boy is placed on mother’s chest for some bonding time. Meanwhile, the mother continues to be cared for by a team of physicians and nurses who aid in the delivery of the placenta.
Until recently, cord clamping was routinely done in less than a minute1 in an effort to deliver the baby and limit blood loss. During pregnancy, blood circulates between the placenta and the fetus via the cord. Clamping leaves excess fetal blood in the placenta. Rich in stem cells, some parents elect to donate or privately bank some of the blood left in the placenta for potential future use. Otherwise, this blood gets discarded.
In an effort to provide Jacob with the very best start possible, we are now asking the question, Should cord clamping be delayed past 1 minute (“delayed clamping”) to allow for the transfer of up to an additional 30% of fetal blood from placenta to the baby at the time of delivery?2
The placenta: a sac of blood
A dramatic transformation occurs in a baby’s first minutes outside the womb. For nine months, the growing fetus is dependent on the placenta for its source of oxygen and nutrients. Blood from the mom and fetus fills the placenta in separate compartments that come into very close contact without physically mixing. Maternal blood brings in oxygen and nutrients (including iron) to the placenta, while fetal blood brings in blood lacking in oxygen and nutrients. An exchange occurs in the placenta, allowing the fetus to transfer waste to the mother and receive oxygen and nutrients from the mother. Once separated from the placenta, the baby learns to use his lungs to breathe and ingest breast milk or formula for nutrients.
What happens to all the blood in the placenta when the cord is cut? If the cord is clamped and cut immediately after labor, the fetal blood that traveled to the placenta during pregnancy (Figure 1, red spaces) gets trapped in the placenta (Figure 1, circle). A small amount of it moves from the placenta to the baby (Figure 1, smiley face) in the time that it takes physicians to prepare the cord for cutting (estimated at 15 seconds). The longer physicians wait to clamp the cord, more blood can travel from the placenta to the baby.2 Scientist found that waiting longer than a minute could provide the baby with an additional 30% more blood.2
What does this mean for a baby born weighting 3kg (about 6.6 pounds)?
A 3kg baby has about a cup of blood circulating at the time of birth.2 If the cord gets clamped within 15 seconds, almost half a cup of blood is retained in the placenta.2 Waiting a minute can provide the baby with an additional quarter of a cup of blood.2
Going back in time: lessons from our predecessors
Early cord clamping was not always the norm. Our predecessors were proponents of delayed cord clamping. In 1801, Erasmus Darwin warned, ‘Another thing very injurious to the child, is the tying and cutting of the navel string too soon; which should always be left till the child has not only repeatedly breathed but till all pulsation in the cord ceases. As otherwise the child is much weaker than it ought to be’.3 How did early cord clamping become common practice in modern medicine?
Babies who struggle to take their first breath are clamped early to prioritize resuscitation. Early clamping also evolved out of the practice of active management of the third stage of labor to assist with delivery of the placenta and reduce maternal blood loss. This final stage of labor is the time from the delivery of the baby to the delivery of the placenta.4 Pitocin is given to induce contractions that constrict the blood vessels feeding the placenta and aid in its delivery.5 Active management shortens the duration of the third stage of labor and significantly decreases postpartum hemorrhage (maternal blood loss) following birth.6 Postpartum hemorrhage occurs in approximately 4 percent of vaginal deliveries and is responsible for 25 percent of all maternal childbirth-related deaths.7 Early cord clamping is commonly practiced to decrease the time of the third stage of labor and maternal blood loss. However, in 2008, a Cochrane review reported that studies show no increase in postpartum hemorrhage in women after delayed cord clamping.8 Is it time to reconsider our predecessors’ warnings in case where both mother and baby are healthy?
Today, research provides evidence for the health benefits associated with delayed cord clamping that Darwin hinted at in the 1800s.4 The benefits of delayed cord clamping for babies born early (premature) have already been recognized and implemented in clinical practice.9 Now, scientists and physicians are exploring the possibility that term babies may also benefit from delayed cord clamping. A Cochrane review published July 2013 announced that “delayed clamping of the umbilical cord in healthy term infants appears to be warranted”.10 They found that babies with later clamping weighed more and were less likely to be iron-deficient three to six months after birth compared to term babies who had early cord clamping.10
Pumping iron: the importance of iron in infant development
Iron is crucial during the first six months of life when the baby is undergoing rapid growth. During this period, the baby is receiving its nutrients from breast milk. Although not rich in iron,11 the baby absorbs a large percentage of the iron in breast milk12 but also depends on the stores of iron he received from the mother (through the placenta) during pregnancy. It has been estimated that delayed cord clamping can provide the baby with an additional three months of iron that is stored for use during the early months of life until the baby starts eating iron rich food.12 In certain scenarios, this extra iron may be critical if the baby did not have the opportunity to build up his iron stores during pregnancy and is at risk of iron deficiency. This baby may have been born prematurely or to a mother who was iron deficient.13 However, healthy term babies born to healthy moms may also require extra iron. The extra iron from delayed cord clamping has shown to reduce risk of anemia soon after delivery and months later.14
The potential and reality of stem cells today
Fetal blood is rich in stem cells. These cells are desired for their potential to develop into any mature cell. For example, a stem cell can become a heart cell, a brain cell or a liver cell, depending on the biological signals that direct its growth pattern. In the fetus, stem cells can be found in the blood. Once isolated, scientists can theoretically push these cells to develop into various desired cell type with the potential to treat disease. While the application of these cells in the clinic is still preliminary, scientists and physicians are starting to harness the power of these cells to treat cancers and various disorders of the blood, immune system, and metabolism.reviewed in 15
For the baby, development does not cease at birth. The brain undergoes significant growth for years after birth that manifests into an ability to move around, communicate and understand the surrounding social environment. Part of this growth is the commitment of stem cells to various cells of the brain that will carry out these functions. Does the baby need the extra stem cells that are trapped in the placenta with early cord clamping? The theory is that these cells have the potential to impact the developmental of the brain and other organs. Because of this potential, we wonder if having more of them could be better for the baby. Some also argue that premature babies might especially benefit from greater numbers of stem cells since their nine month developmental process was cut short. The reality is, we just do not know. No evidence is available at this time that shows that the stem cells gained during delayed cord clamping are 1) needed since the baby has a lot of stem cells already and 2) will have an impact on the babies immediate and long-term health. Currently, we think that stem cells have the potential to benefit health but we do not have the evidence to show that is the case.
The counter argument: “Too much, Too soon”
In light of no formal guidelines for the timing of cord clamping in term infants, some practitioners cut the cord out of fear of overloading the baby with extra blood. Too much blood increases risks for polycythemia,16 a condition where the baby has too many red blood cells. An increase in red blood cells causes the blood to get thicker, the flow of blood slows and blood clots may form. However, the Cochrane review reports no differences in polycythemia in babies what had early versus late cord clamping among five trials that reported data on polycythemia.10
Some studies have shown that babies of delayed cord clamping have higher risk of developing jaundice compared to babies of early cord clamping.10 Too much blood can lead to jaundice,17 a condition that results in yellowing of the skin because of excess amounts of newborn bilirubin. Bilirubin is a yellow pigment that is released during the normal breakdown of red blood cells. Normally cleared by the liver, a newborn’s still-developing liver may not be able to efficiently clear the bilirubin. While jaundice is common in newborn and benign when blood levels of bilirubin are low, high levels of bilirubin can affect brain cells and cause permanent damage—a condition called “kernicterus.”18 Exposure of the newborn to specific wavelengths of light in a process called phototherapy is an effective treatment for jaundice but it often prolongs the time that the neonate must spend in the hospital.19 The authors of the Cochrane review conclude that “delayed cord clamping is likely to be beneficial as long as access to treatment for jaundice requiring phototherapy is available”.10
Should you delay cord clamping for your baby?
When it comes to cord clamping, every baby will be different. Delayed cord clamping may or may not be beneficial for your baby. We know there are benefits for some preterm and term babies. We also know some babies will have to spend more time in the hospital to undergo phototherapy after delayed cord clamping. To help you decide if delayed cord clamping should be part of your birth plan, discuss cord clamping and what you know and do not know with your obstetric and pediatric providers.
It is also important to remember that birth plans may not always go as planned. Complications may occur during delivery that could make delayed cord clamping dangerous. If you decide on delayed cord clamping, be open-minded about early cord clamping if the baby needs to be attended to immediately. Delaying that care may put the baby at risk.
This work is funded in part by the Graduate Student Internships for Career Exploration (GSICE) program at UCSF.
This post was checked by the following science articles:
1. Philip A, and Saigal S. When Should We Clamp the Umbilical Cord? NeoReviews. 2004; 5(4): e142 -e154.
2. Yao AC, Moinian M, Lind J. Distribution of blood between infant and placenta after birth. Lancet. 1969;2871-873.
3. Darwin E. Zoonomia. Volume III. Dublin: B Dugdale, 1801
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12. Saarinen, U. M., Siimes, M. A. & Dallman, P. R. (1977) Iron absorption in infants: high bioavailability of breast milk iron as indicated by the extrinsic tag method of iron absorption and by the concentration of serum ferritin. J. Pediatr. 91:36-39.
13. Chaparro, C.M. Timing of umbilical cord clamping: effect on iron endowment of the newborn and later iron status. Nutr Rev. 69 Suppl 1: p. S30-6. 2011.
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17. Blackburn S. Hyperbilirubinemia and neonatal jaundice. Neonatal Netw. 1995;1415-25.
18. Barateiro A, Miron VE, Santos SD, Relvas JB, Fernandes A, Ffrench-Constant C, Brites D. Unconjugated bilirubin restricts oligodendrocyte differentiation and axonal myelination. Mol Neurobiol. 2013;47(2):632-44.
19. American Academy of Pediatrics Subcommittee on Hyperbilirubinemia. Management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation. Pediatrics. 2004;114(1):297.