“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, a portion of blood being left in the placenta which ought to have been in the child.” (Darwin 1801)
This is an adapted excerpt from Birthing Your Placenta: the third stage of labour, in which Nadine Edwards and Sara Wickham explain the evidence on many aspects of the birth of the placenta for those wishing to better understand and make informed decisions about this element of birth.
There hasn’t been much interest in studying what happens in women’s and babies’ bodies if birth is not interfered with. Because of this, much of what we know about the advantages of waiting has come out of research studies looking at the disadvantages of immediate cord clamping. This is sadly not a unique situation. There are many other situations in maternity care where normal physiology is not well understood and in which we may well be causing more harm than good by interfering on a routine basis.
Evidence of the advantages of patience
The transfer of the blood that has been circulating in the placenta in the moments after birth is the main reason that it is important to allow time before clamping and cutting the baby’s cord. Many practitioners are aware that the baby needs to be able to access its full complement of blood in order to support lung expansion and additional blood volume requirements from the placenta which occur as the first breaths of air are taken. If the cord is clamped immediately at birth, blood from the placenta cannot flow through it and this blood therefore cannot be used to support the process of lung expansion and respiration. Blood then has to be ‘borrowed’ from the rest of the baby’s circulation in order for its lungs to become fully functioning, even though the baby’s other vital organs also need blood to function fully and optimally (Mercer et al 2008, Mercer & Erickson-Owens 2010).
We are only really beginning to discover the myriad reasons why babies need to be able to access their full complement of blood before we interfere with the supply by clamping and cutting the cord. Our knowledge of this area has increased fairly rapidly over the past few years, although we still have a lot to learn. In 1974, Yao and Lind found that, when a baby received its full quota of blood, it was better able to maintain its haematocrit levels (ratio of red blood cells to total volume of blood). In the past, commentators knew that this quota of blood was important (Inch 1983) but it is only more recently that we have come to understand the implications of early cord clamping more fully.
The research in this area has now become more widely known and incorporated into practice. A number of studies have shown that allowing the cord to remain intact for a period of time confers significant advantages to the baby (Mercer & Erickson-Owens 2010, Hutchon 2012, Bhatt et al 2013, McDonald et al 2013, Mercer & Erickson-Owens 2014, Hooper et al 2015). Our current understanding is that allowing the cord to remain intact helps a baby to establish their breathing and circulation, which is particularly advantageous for babies who are compromised or born prematurely (Mercer & Erickson-Owens 2010). Allowing the cord to remain intact can lead to a reduction in breathing difficulties and less need for oxygen, ventilation and blood transfusion (Mercer 2001). Other benefits include an improvement in cardiac (heart) function (Bhatt et al 2013, Hooper et al 2015), an increase in the baby’s iron stores (Chaparro et al 2006, Andersson et al 2011) and neurological advantages (Hutchon & Wepster 2014).
We know that later cord clamping can lead to a baby receiving almost a billion more stem cells (which have healing qualities) than if the cord is clamped and cut early (Mercer & Erickson-Owens 2010). Later cord clamping can also reduce the likelihood of severe infection (also known as sepsis) in pre-term babies (Mercer & Erickson Owens 2006, Mercer & Erickson Owens 2010). Hutchon (2016b) suggested that the intervention of immediate cord clamping may cause some babies to need to be resuscitated. Other studies show that babies whose cords are clamped earlier experience disadvantages. Mercer et al (2008) note that babies who experience immediate cord clamping are likely to have hypovolaemia (too little blood volume) and suggest that this can lead to the release of substances called inflammatory cytokines, which are associated with cerebral palsy.
These benefits are summarised in systematic reviews and acknowledged in reviews looking at the ‘management’ of the birth of the placenta. In 2010, the Cochrane review comparing active management with physiological placental birth noted that about 20 per cent of a baby’s blood volume is lost when the cord is clamped early (Begley et al 2010). This is also acknowledged in reviews on cord clamping, for instance where McDonald et al (2013) note Mercer’s (2001) revelation that “…placental transfusion can provide the infant with an additional 30% more blood volume and up to 60% more red blood cells.” The benefits of higher iron stores are experienced for several months after birth, even if the cord remains intact for only 1-3 minutes after birth (McDonald et al 2013).
If you’d like to know more about what happens in premature babies, how long the evidence says is best to wait and so on, please see our book, which contains all of that and much, much more!
Andersson O, Hellstrom-Westas L, Andersson D et al (2011). Effect of delayed versus early umbilical cord clamping on neonatal outcomes and iron status at 4 months. BMJ 2011 343: d7157.
Begley CM, Gyte GM, Murphy DJ et al (2010). Active versus expectant management for women in the third stage of labour. Cochrane Database of Systematic Reviews Issue 7.
Bhatt S, Alison BJ, Wallace EM et al (2013). Delaying cord clamping until ventilation onset improves cardiovascular function at birth in preterm lambs. The Journal of Physiology, 591(8), 2113-26.
Chaparro CM, Neufeld LM, Tena Alavez G et al (2006). Effect of timing of umbilical cord clamping on iron status in Mexican infants: a randomised controlled trial. Lancet, 367(9527): 1997-2004.
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Hooper SB, Polglase GR, Te Pas AB (2015). A physiological approach to the timing of umbilical cord clamping at birth. Archives of Disease in Childhood – Fetal & Neonatal Edition 100(4), F355-360.
Hutchon DJ (2012). Immediate or early cord clamping vs delayed clamping. Journal of Obstetrics & Gynaecology, 32(8), 724-29.
Hutchon DJR (2016b). Ventilation, chest compression and placental circulation at neonatal resuscitation – ILCOR recommendation 2015. Journal of Paedatric Neonatal Disorders 1(1): 1-6.
Hutchon DJR & Wepster R (2014). The estimated cost of early cord clamping at birth within Europe. International Journal of Childbirth, 4(4): 250-56.
Inch S (1983). Third stage management. ARM Newsletter 19: 7-8.
McDonald SJ, Middleton P, Dowswell T et al (2013). Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes. Cochrane Database of Systematic Reviews 2013, Issue 7. Art. No.: CD004074. DOI: 10.1002/14651858.CD004074.pub3
Mercer JS (2001). Current best evidence: a review of the literature on umbilical cord clamping. Journal of Midwifery and Women’s Health 46(6): 402–14.
Mercer J & Erickson-Owens D (2006) Delayed cord clamping increases infants’ iron stores. Comment. Lancet 367(9527): 1956-58.
Mercer J & Erickson-Owens D (2010). Evidence for neonatal transition and the first hour of life. In: Walsh D, Downe S (eds). Essential midwifery practice: intrapartum care. Wiley, 81-104.
Mercer J, Skovgaard R, Erickson-Owens D (2008). Fetal to neonatal transition: first do no harm. In: Downe S (eds). Normal Childbirth: evidence and debate. Churchill Livingstone, 149–74.
Yao AC & Lind J (1974). Placental transfusion. American Journal of Disease in Childhood. 127(1):128-41.
© Sara Wickham and Nadine Edwards 2019