Choices about your baby’s umbilical cord and clamping– do you have all the information?
In Australia, the Queensland Centre for Mothers and Babies are producing a decision aid for women titled (draft) ‘Choices about your baby’s umbilical cord’.
From their website: “The Queensland Centre for Mothers & Babies (QCMB) is an independent research centre based at the University of Queensland in Brisbane and is funded by the Queensland Government. The role of the QCMB is to work towards consumer-focused maternity care that is integrated, evidence-based, and provides optimal choices for women in Queensland.”
Clearly written and accessible, there is a lot to admire about the decision aids being produced for women by this independent research centre. The Having a Baby in Queensland book (available online here) is another outstanding example of a publication designed to share evidence with women in a way that is easy to compare and understand.
As part of the consultation process for developing the decision-aid on cord clamping, I contributed a substantial amount of feedback and evidence to the research officer. Their consultation encompassed maternity care providers, consumers and other stakeholder groups which was very pleasing to see.
Through the feedback process I learnt that because randomised controlled trials (RCTs) are the minimum standard of evidence for the information sheet, there are limitations to the information that can be shared with women in this decision aid.
Cord clamping choices – but what about physiology and infant blood loss?
In this article, I offer to share the information that won’t be included in the decision aid for birthing women regarding their babies umbilical cord.
The information I would like to see women have access to is mainly concerned with the timing of physiological cord closure and neonatal blood loss from premature cord clamping.
When reading a decision aid informed only by RCTs, women may miss out on other important scientific information that could impact on their choices about cord clamping.
Restricted to information only produced in a clinical trial designed to measure various interventions, women may miss out on important evidence about normal physiology of birth – evidence about the impact of cord clamping on placental transfusion, neonatal transition and the impact of infant blood loss from untimely and un-physiologic cord clamping.
For instance, the analyses of randomised controlled trials in the relevant Cochrane Reviews do not measure:
– residual placental blood volume;
– placental transfusion;
– timing of physiological cord closure;
– feto-maternal transfusion;
– or longer-term neonatal and childhood neurodevelopmental outcomes.
Information women should also know when making decisions about cord clamping
Image produced by Nurturing Hearts Birth Services, featuring the changes over 15 minutes after birth in an intact umbilical cord.
Placental transfusion and pulsations can take longer than 3 minutes
- “Gravity and positioning of the infant immediately after birth
Gravity affects the amount of placental transfusion that an infant receives. Holding the infant above the level of the placenta (>10cm) slows the placental transfusion and lowering the infant accelerates it. For example, placing an infant skin-to-skin on the maternal abdomen slows the rate of the placental transfusion. By measuring the amount of blood left behind in the placenta, after infants are placed skin-to-skin, a 2-minute delay in cord clamping results in only a partial placental transfusion….a 2-minute delay results in an average of 25 mL/kg of whole blood left behind in the placenta compared with a 5-minute delay that leaves only an average of 11 mL/kg. A 5-minute delay in cord clamping allows the infant who is skin-to-skin to receive a full placental transfusion.” Mercer and Erickson-Owens (2012) Rethinking Placental Transfusion and Cord Clamping Issues http://www.ncbi.nlm.nih.gov/pubmed/22843002
- “The time at which net placental flow appeared to cease for most infants was at 2 minutes (data not shown). Nevertheless, for some infants, flow continued for up to 5 minutes.” Farrar. (2010). Measuring placental transfusion for term births: weighing babies with cord intact.
- “The umbilical arteries usually cease to pulsate within five to 10 minutes after birth.” Lind (1965). Adaptation to Placental Transfusion
- “While this entire process typically lasts about 3 minutes, it may take longer or occur in less than 1 minute.” Morley, GM (1998) citing Linderkamp (1982) Placental Transfusion: determinants and effects
- Midwife academic Rachel Reed writes “Textbooks will tell you 3-7 minutes, but I have felt cords pulse for longer than that.”
Why is the “3 minute” wait before clamping so ubiquitous?
Using indirect methods, Yao et al estimated that placental transfusion was complete within 3 minutes – in the presence of powerful uterotonics and usually with the baby held below the placenta.
With no other studies like it until more recent times, most RCTs have therefore determined the timing of delayed clamping to be 3 minutes.
The actual timing or indicators of physiological cord closure have not been determined by a RCT.
Blood volume and blood loss in the baby
These studies provide information about neonatal blood volume and blood loss associated with premature and un-physiologic cord clamping:
- Andersson (2011) Mean birth weight was significantly higher in DCC group compared with early clamping (early 3533 vs delayed 3629 g). (This weight difference signifies loss of placental transfusion/blood volume in the early clamped group.)
- Mercer et al (2012; 2002) citing Yao et al (various) and Linderkamp (1992). Term infants with immediate clamping have approx. 70ml/kg blood at birth. Term infants with delay of 3 mins have approx. 90ml/kg blood at birth, an increase of 30% in blood volume.
- Jahazi (2008) –hematocrit was similar between early and delayed clamping groups yet a great amount of PRBV (residual placental blood volume) blood was drained from [the placenta] in early clamped group (30 s). (This indicates the babies in the early clamped group were deprived of placental transfusion)
- In Gupta and Ramji (2002; RCT) study, infants with immediate clamping had lower birth weight – and the rates of anaemia at 3 months were 7.7 times higher (compared with infants in delayed clamping group).
- Nelle (1995, controlled study) the infants in delayed group (>3mins) had 32% higher blood volume. Author states clamping <10s deprives infants of placental transfusion and increases risk of hypovolemia and anaemia.
- Nelle (1993, controlled study) found the residual placental volume higher in <10s clamping group.
For 3kg infant:
EC <10s = 135ml in placenta, 210ml in baby
DC >3mins= 75ml in placenta, 270ml in baby
Active management of placenta and infant blood loss
“There was also a decrease in the baby’s birthweight with active management, reflecting the lower blood volume from interference with placental transfusion.”
“In addition, it decreased the baby’s birthweight, possibly due to clamping the cord before pulsation ceased, with a possible loss of approximately 80 mL of blood.”
“The negative effects of active management appear, in the main ….early cord clamping leading to a 20% reduction in the baby’s blood volume.” Cochrane Review (2011), Active versus expectant management for women in the third stage of labour
Analysis 1.30. Comparison 1 Active versus expectant management of 3rd stage of labour (all women), Outcome 30 Birthweight. (Analysis of two studies that included birthweight, results favouring expectant management.)
Information from studies measuring physiology, not cord clamping
“Estimates of the volume and duration of placental transfusion are largely derived from studies conducted 50 years ago, most of which used indirect methods.5–8 For term infants having a normal vaginal birth, estimates range from 60 to 240 ml, with an average of 100 ml often quoted.
This is equivalent to 20–30% of blood volumeand red cell mass at birth. The speed and duration of placental transfusion may also be influenced by gravity and the uterotonic drug. Raising or lowering the baby 20 cm or more from the level of the placenta will affect placental transfusion.
The time at which net placental flow appeared to cease for most infants was at 2 minutes (data not shown). Nevertheless, for some infants, flow continued for up to 5 minutes. For term infants, placental transfusion contributes between one-third and one-quarter of total potential blood volume at birth.” (bold emphasis mine)
Women can have active management of the placenta and delayed cord clamping
Since 2007, the World Health Organisation has advised 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).”
The WHO definition of active management includes this delayed clamping and cutting of the umbilical cord.
There is a staggering number of women and students that are told early cord clamping is a necessary component of active management of the third stage of labour.
In fact, early cord clamping and cord traction are unproven components of active management and new studies are demonstrating the need to reassess these components, as well as the position that active management is the management of choice for all women.
More recent research is showing that routine active management in low risk women (in developed nations) can be associated with higher rates of post partum hemorrhage.
I look forward to the finalisation of the QLD Mother and Babies decision aids on placental birth and cord clamping, and the provision of more evidence being shared with mothers.
Furthermore, I anticipate future RCTs will provide women with more information regarding the impact of cord clamping – but I shall continue to disseminate this information here in the meantime.