The optimal timing for cord clamping after birth has been the subject of controversy and debate for decades. But what does the research say?
At the beginning of the 1950s, early clamping was defined as clamping of the umbilical cord within one minute of birth, and late clamping, defined as clamping more than five minutes after birth. Today cord clamping is usually performed within 15 to 20 seconds after birth – unless otherwise requested. There have been many studies and reviews done to evaluate the benefits of delayed or late cord clamping and yet no ideal time period has been established.
What the research says
Several systematic reviews have suggested that clamping the umbilical cord in all births should be delayed for at least 30 to 60 seconds. The infant should also be maintained at or below the level of the placenta because more of the blood in the placenta can then flow into the baby’s body before clamping. This increases the baby’s blood volume, reducing the need for blood transfusion, decreaing the incidence of intracranial haemorrhage (bleeding in the skull) in preterm infants, and less incidence of iron deficiency in term infants.
Some studies of blood volume changes after birth were done by researchers in Sweden, United States, and Canada, and it was reported that in healthy term infants, more than 90 percent of blood volume was achieved within the first few breaths the infant took after birth. Because of these findings, the interval between birth and umbilical cord clamping has begun to be shortened. Especially in wealthier nations it is common practice to clamp the baby's umbilical cord less than a minute after birth.
However, a recent review of published studies, (Cochrane database of systemic reviews), data collected from 4000 women suggests that delayed cord clamping results in healthier blood and iron levels in babies.
Philippa Middleton of the Australian Research Centre for Health of Women and Babies at the University of Adelaide, explains: "In light of growing evidence that delayed cord clamping increases early haemoglobin concentrations and iron stores in infants, a more liberal approach to delaying clamping of the umbilical cord in healthy babies appears to be warranted."
Stopping the blood from the placenta reaching the baby before the final few pulses, means there may be a chance the infant will not receive enough blood from the mother and may in turn have lower iron levels.
While there are many benefits, Middleton says they did find that clamping the cord later was linked to higher numbers of babies needing treatment for jaundice. "The benefits of delayed cord clamping need to be weighed against the small additional risk of jaundice in newborns. Later cord clamping to increase iron stores might be particularly beneficial in settings where severe anaemia is common."
The jury is still out
Currently, there is insufficient evidence to support or to refute the benefits from delayed umbilical cord clamping for term infants that are born in settings with rich medical resources.
Although a delay in umbilical cord clamping for up to 60 seconds may increase total body iron stores and blood volume (which may be particularly beneficial in populations in which iron deficiency is prevalent) these potential benefits must be weighed against the increased need for neonatal phototherapy (treatment for jaundice).
No difference is apparent between infants who undergo early umbilical cord clamping versus those who undergo delayed umbilical cord clamping with respect to immediate birth outcomes, such as Apgar scores, umbilical cord pH, or respiratory distress.
Although maternal outcomes have not been rigorously studied, the incidence of postpartum haemorrhage is reported to be similar between immediate umbilical cord clamping groups and late umbilical cord clamping groups.
Evidence does however support delayed umbilical cord clamping in preterm infants. As with term infants, delaying umbilical cord clamping to 30-60 seconds after birth with the infant at a level below the placenta is associated with neonatal benefits, including improved transitional circulation, enhanced establishment of red blood cell volume, and less need for blood transfusion.
The reviewers concur "a more liberal approach" to delaying cord clamping is likely to benefit babies, "as long as access to treatment for jaundice requiring phototherapy is available."
What is cord clamping?
During pregnancy your baby is attached to the placenta via the umbilical cord. Oxygen and nutrients are passed from the blood circulating through the placenta via the umbilical cord to your baby, and waste is removed in the same way. In the majority of births, as soon as the baby emerges, a clamp is attached to the cord to stop blood flowing through it. The cord is then cut. This stump eventually dries out and drops off (after a week to ten days) to form a belly button.
*First published in the December 2013/January 2014 issue of Your Pregnancy Magazine