DELAYED CORD CLAMPING
Delayed cord clamping is a birth practice where the umbilical cord is not clamped or cut until after pulsations have ceased, or until after the placenta is delivered. A growing number of parents are choosing delayed cord clamping for their baby, while some believe in non-severance (lotus birth). (1)
While an intact cord after birth is the biological norm, the notion of ‘delayed clamping’ is a response to the modern practice of immediate or early cord clamping. Cord clamping is a surgical intervention in the normal birth process, which irrevocably changes the anatomy and physiology of the baby at birth.
All parents should be informed about cord clamping and discuss their preferences with their clinical care providers. There are currently several ‘standard’ practices that can result in immediate clamping, such as ‘active management’, surgical intervention, responses to a baby’s condition at birth, and collecting ‘cord blood’ for testing or banking. Parents wishing to delay cord clamping may need to state verbally and in writing their refusal to consent to early cord clamping.
There is compelling evidence that refutes immediate cord clamping and supports delayed cord clamping as a safer birth practice. (2)
BENEFITS OF DELAYED CORD CLAMPING
The benefits of delayed cord clamping for the baby include a normal, healthy blood volume for the transition to life outside the womb; and a full count of red blood cells, stem cells and immune cells. For the mother, delayed clamping keeps the mother-baby unit intact and can prevent complications with delivering the placenta. (1)
Dr Judith Mercer is a leading expert on cord clamping and has produced an extensive amount of evidence regarding the benefits of delayed clamping for both full term and very preterm infants. With colleagues, her review of the available literature showed that delayed cord clamping produced higher blood pressure, higher hematocrit levels, more optimal oxygen transport and higher red blood cell flow to vital organs, reduced infant anaemia and increased duration of breastfeeding. For very preterm infants, the benefits also included fewer days on oxygen and ventilation, fewer transfusions, and lower rates of intraventricular hemorrhage and late-onset sepsis. (2)(3)
As well as researching the benefits of delayed clamping, Mercer et al have also established the importance of blood volume for the fetal-to-neonatal transition at birth.
Before birth, the baby and placenta share a circulating blood supply that is separate to the mother’s. Inside the uterus, the placenta and umbilical cord provides the baby with oxygen, nutrients and clears waste. During fetal life, the baby’s organs only need a small flow of blood while the placenta performs the role of lungs, kidneys, gut and liver for the baby. This is why a significant portion of the baby’s total blood volume is in the placenta at any given time. The blood circulating the placenta and cord is not ‘extra’ blood or waste – it belongs to the baby. (4)
Immediately after birth, the cord pulsates as the placenta continues to provide essential oxygen and nutrients, and begins to deliver blood back to the baby. This transfer of blood is called placental transfusionand it is a vital part of the birth process.
Placental transfusion is the system that provides the baby with red blood cells, stem cells, immune cells and blood volume. Delayed cord clamping allows time for the placental transfusion, ensuring safe oxygen levels and blood volume in the baby. (4)
At the time of birth, the extra volume of blood needed for the fetal-to-neonatal transition resides in the placenta. Placental transfusion sends this ‘respiratory’ volume of blood back to the baby, to prepare and support the fetal organs to transition to ‘adult’ breathing and circulation. It also provides an adequate number of red blood cells to then transport oxygenthroughout the baby’s body. (5)
For the fetal lungs to switch from a ‘fluid-filled’ organ to perform gas exchange, the baby’s heart must now direct 50% of cardiac output to the lungs (blood sent from the baby’s heart, which was only 8% during fetal life). This perfusion of blood helps to expand the air sacs, clear fluid from the lungs and keep the lungs expanded.
As the cord pulsates, the baby receives the extra blood volume and gently transitions to breathing. The massive increase in blood flow to the lungs takes place, without sacrificing blood flow to the other organs. Delayed cord clamping can ensure the baby has a sufficient blood supply for this fetal-to-neonatal transition. (4)(5)
HOW TO DELAY CORD CLAMPING
In normal birth, delayed clamping is achieved by leaving the umbilical cord intact during the placental transfusion and not clamping until the cord has stopped pulsating.
Once the baby has begun to breathe and achieved a normal circulating blood volume, the cord ceases to pulse (cord appears white and flaccid).
A study by Yao, Moinian and Lind (1969) estimates distribution of blood between infant and placenta after birth takes approximately three minutes after birth. It is therefore assumed transition and physiological blood volume is achieved within three minutes, however pulsations and normal cord closure can take longer for some babies. Midwife academic Rachel Reed writes “Textbooks will tell you 3-7 minutes, but I have felt cords pulse for longer than that.” (5)
In surgical deliveries (caesarean section), a ‘delay’ in clamping can be achieved (except in cases where there is incision or damage to the placenta). The baby can be held below the level of the placenta to assist with the transfer of blood from the placenta to the baby. Some practitioners may choose to “milk” the blood in the cord towards the baby and/or wait 40 seconds or more before clamping. With a ‘lotus’ caesarean section the placenta may remain attached to the baby, without clamping the cord. (6)
The World Health Organisation states the “optimal time to clamp the umbilical cord for all infants regardless of gestational age or fetal weight is when the circulation in the cord has ceased, and the cord is flat and pulseless (approximately 3 minutes or more after birth).” (7)
RISKS OF IMMEDIATE CORD CLAMPING
For many decades, various studies have shown that immediate or early cord clamping disrupts normal physiology, anatomy and the birth process – it severs the baby from the still-functioning placenta and halts the circulation of blood.
Dr Mercer asserts the practice of immediate and early cord clamping developed without regard for the baby and can cause a baby’s blood volume to vary 25% to 40%. “Such a massive change occurs at no other time in one’s life without serious consequences, even death. Early cord clamping may impede a successful transition and contribute to hypovolemic and hypoxic damage in vulnerable newborns.” (2) (Low blood volume and oxygen deprivation.)
Large studies have shown that immediate cord clamping can result in lower iron stores in the baby for up to 6 months after birth. While not all the implications of a reduced iron status are understood, iron deficiency in the first few months of life is associated with neurodevelopmental delay, which may be irreversible. (8)
Early cord clamping can cause complications for the mother, too. There is some evidence that early clamping increases the risk of post-partum hemorrhage and retained placenta by engorging the placenta with the baby’s blood. This makes it harder for the uterus to contract and expel the placenta. The third stage contractions can also force the baby’s blood into the mother’s blood supply. In some women, a feto-maternal haemorrhage can increase the chance of serious blood-group incompatibility problems in future pregnancies.
Cord clamping and the vulnerable newborn
When the cord is clamped, the volume of blood within the newborn baby is fixed. (4) While the normal, healthy full term baby routinely survives early cord clamping, some babies are born prematurely and/or with a dangerously low blood volume. Low blood volume (hypovolemia) can be caused by compression on the cord, a tight nuchal cord (cord around neck), a large baby that is a very tight squeeze and shoulder dystocia.
In hospital birth it is routine to immediately clamp and cut the cord of compromised infants to transfer them to a flat surface for resuscitation. However, since clamping leaves the baby with a low blood volume, the consequence of clamping can be fatal. If the baby survives, the low blood volume can mean blood has to be sacrificed from other organs to sustain the lungs, and organ damage can be the result (including mild to severe brain damage).(4)
In the UK, a team of medical professionals have designed the BASICS trolley (Bedside Assessment, Stabilisation and Initial Cardiorespiratory Support). The trolley was designed to stop the immediate clamping and relocation of the baby. As it stands, babies born out of hospital and at home are more likely to have the cord kept intact during resuscitation.
Cord blood banking
Decisions about ‘cord blood’ banking should factor the known risks of immediate cord clamping and disruption to the birth process. With most ‘cord blood’ collection, immediate cord clamping is done to harvest as much of the infant’s blood circulating the cord and placenta as possible. Parents should be informed of the risks and benefits of collecting blood from the umbilical cord and placenta before deciding on blood banking. The benefits of placental transfusion are significant for low-risk families without a member requiring a transplant.
RISKS OF DELAYED CORD CLAMPING?
As for risks with delayed clamping, Mercer found that for both term and preterm infants there were few, if any, risks. In the trials where infants had delayed clamping they were without symptoms of polycythemia or significant hyperbilirubinemia. (3) (Conditions that were once attributed to a baby receiving a normal blood volume at birth.)
It is currently advised that delayed clamping is not safe for babies born to mothers with HIV and other blood-borne viruses. Immediate clamping and “milking” blood away from the baby is standard practice in an attempt to minimise risk of transmission – however Van Rheenen states there is no biological evidence that delayed clamping increases the risk of HIV particles being transferred to the baby. (9) Parents may wish to discuss the most up-to-date research with their clinical care providers to inform future decision-making.
Delayed cord clamping leaves the cord alone after birth and avoids disrupting the normal birth process. While the cord is pulsating, placental transfusion is supplying the baby with oxygen, nutrients and an increased blood volume to support the transition to life outside the womb.
Delayed cord clamping confers many benefits to the newborn baby including higher number of red blood cells, stem cells and immune cells at birth. In premature or compromised babies, delayed cord clamping may provide essential life support, restore blood volume and protect against organ damage, brain injury and death.
(1) Buckley, S.J. “Leaving Well Enough Alone: Natural Perspectives on the Third Stage of Labor” , Gentle Birth, Gentle Mothering: A Doctor’s Guide to Natural Childbirth and Gentle Early Parenting Choices (2009) New York: Celestial Arts
(2) Mercer J. Current best evidence: a review of the literature on umbilical cord clamping. J Midwifery Womens Health2001 Nov-Dec;46(6):402-14
(3) Mercer, J. et al, Delayed Cord Clamping in Very Preterm Infants Reduces the Incidence of Intraventricular Hemorrhage and Late-Onset Sepsis: A Randomized, Controlled Trial. Pediatrics Vol. 117 No. 4 April 1, 2006
pp. 1235 -1242 (doi: 10.1542/peds.2005-1706)
(4) Mercer, J. Skovgaard, R. & Erickson-Owens, D. “Fetal to neonatal transition: first, do no harm“, Normal Childbirth: Evidence and Debate second edition (2008) edited by Downe, S. pp149-174
(5) Yao, A.C., M. Moinian, and J. Lind. (1969). Distribution of blood between infant and placenta after birth. Lancet, 1969.626(2): p. 871-873
(6) Hutchon, D. BSc, MB, ChB, FRCOG, Guideline for the management of Caesarean Section deliveries. Found at http://www.hutchon.net/NFMMSIG/cordclamp.htm
(7) WHO information sheet: “Optimal timing of umbilical cord clamping,” Essential delivery care practices for maternal and newborn health and nutrition. Found at http://amro.who.int/English/AD/FCH/CA/Delivery_care_practices.pdf
(8) Royal College of Obstetricians and Gynaecologists (UK) Opinion Paper, Clamping of the Umbilical Cord and Placental Transfusion. (2009) Found at http://www.rcog.org.uk/clamping-umbilical-cord-and-placental-transfusion
(9) Van Rheenen, P. “Effect of Timing of Cord Clamping on Neonatal Venous”, The Role of Delayed Umbilical Cord Clamping to Control Infant Anaemia in Resource-Poor Settings. (2007) Rozenberg Publishers pp 151-158
Mercer, J. Skovgaard R. Neonatal transitional physiology: a new paradigm. J Perinat Neonatal Nurs.2002 Mar;15(4):56-75. Review