A case for delayed umbilical cord clamping
The optimal timing of umbilical cord clamping has been debated in the scientific literature for over a century. “Early” cord clamping is generally carried out in the first 60 seconds after birth, whereas “delayed” umbilical cord clamping is carried out more than 1 min after the birth or when cord pulsation has ceased. However, the timing of cord clamping continues to vary according to clinical policy and practice, though surveys of cord clamping practices in a variety of settings and countries indicate that early cord clamping is more frequently practiced.
There is growing evidence that delayed cord clamping is beneficial and can improve the infant’s iron status for up to 6 months after birth. For the first few minutes after birth, there is still circulation from the placenta to the infant. Waiting to clamp the umbilical cord for 2–3 min, or until cord pulsations cease, allows a physiological transfer of placental blood to the infant (the process referred to as “placental transfusion”), the majority of which occurs within 3 min. This placental transfusion provides sufficient iron reserves for the first 6–8 months of life, preventing or delaying the development of iron deficiency until other interventions –such as the use of iron-fortified foods– can be implemented.
Delayed umbilical cord clamping may be particularly relevant for infants living in low-resource settings with less access to iron-rich foods and thus greater risk of anaemia. Anaemia, is a widespread public health problem with major consequences for human health, affecting and hindering social and economic development.
There were no significant differences in the rates of severe postpartum haemorrhage (>1000 mL) or postpartum haemorrhage (>500 mL) between groups with early or delayed umbilical cord clamping. In addition, no significant effect of umbilical cord clamping time was observed in the trials that evaluated the use of manual removal of the placenta (two trials, 1515 women), the need for blood transfusion (two trials, 1345 women), or the length of the third stage of labour (two trials, 1345 women) (17).
Neonatal outcomes (term and preterm infants)
The guideline development group working on the review of the evidence for basic neonatal resuscitation analysed various studies, including many included in the aforementioned Cochrane reviews on preterm and term infants (17, 18). Since additional studies are included in the most recent versions of these Cochrane reviews, a summary of the evidence is provided next. The guideline development group – neonatal resuscitation recommendations on cord clamping (2) discussed the evidence from this review. Fifteen randomized controlled trials (738 infants) have evaluated the effects of umbilical cord clamping time in preterm neonates born predominantly in high-income countries (18). Outcomes studied among preterm infants included risk of mortality, incidence of necrotizing enterocolitis and intraventricular haemorrhage, need for blood transfusions for anaemia or low blood pressure, and hyperbilirubinemia.
No studies in neonates with respiratory depression were identified and few studies measured respiratory outcomes. There was considerable heterogeneity between the included studies in the definition of “late” clamping time (from roughly 30 s to 180 s after birth) and positioning of the infant relative to the placenta or uterus before clamping. There was no difference in risk of mortality between preterm infants with delayed or early umbilical cord clamping (13 studies, 668 infants). Preterm infants with delayed umbilical cord clamping had a lower risk of necrotizing enterocolitis (5 trials, 241 infants) and intraventricular haemorrhage (10 trials, 539 infants). Seven randomized trials (392 infants) looked at the need for blood transfusions for anaemia or low blood pressure among preterm infants; on average, there was approximately a 39% reduction in the need for blood transfusion with delayed umbilical cord clamping. Delayed-clamped infants had significantly higher peak bilirubin concentrations as compared to early-clamped infants, in the seven trials (320 infants) reporting this outcome. There was no significant difference in treatment for jaundice between early- and delayed-clamped infants (three trials, 180 infants), though the treatment criteria probably differed between studies and were not always stated.
Studies (15 RCTs) found no difference in neonatal mortality, or rate of admission to intensive care between early- and delayed-clamped umbilical cord clamping time in term infants from low-, middle- and high-income countries.
Outcomes studied among term infants included neonatal mortality, admission to intensive care, haematological and iron status outcomes at birth and through to 6 months of age, polycythaemia, jaundice, and neurodevelopment.
here was infants. Four studies (954 infants) looked at the risk of anaemia at 3–6 months of age among term infants and no significant difference was found in the rates of anaemia between the delayed- and early-clamping groups.
Five trials of term infants (1152 infants) measured indicators of iron deficiency at 3–6 months of age. Infants with delayed clamping were significantly less likely to have iron deficiency than early-clamped infants, though there was high heterogeneity in this outcome, probably because of different measures/definitions of iron deficiency, as well as the age at which it was assessed. Five trials (1025 infants) reported the effect of timing of umbilical cord clamping on the incidence of polycythaemia among term infants,with no difference between delayed and early umbilical cord clamping. Seven randomized controlled trials
(2324 infants) examined the risk of receiving phototherapy for hyperbilirubinaemia following delayedumbilical cord clamping in term neonates. In the majority of the studies, the criteria used for phototherapy were not strictly defined. Delayed-clamped infants were significantly more likely to require phototherapy for jaundice, with a risk difference of <2% between early- and delayed-clamped infants. Only one study (365 infants) evaluated neurodevelopment in term infants, and found no significant effect of umbilical cord clamping time on the measures assessed at 4 months of age.
immediate umbilical cord clamping following delivery of the baby has been a standard midwifery practice. Upon clamping and cutting of the cord, the baby is handed to the nurse and the placenta delivered. This completes the third stage of labor process.
The WHO has advocated this practice as part of the prevention of excessive postpartum bleeding. The other recommendations include administration of a uterotonic drug to ensure a well contracted uterine and delivery of the placenta as soon as possible.
Recently, there have been advocates of delay cord clamping. The perceived benefits include more blood volume being transfused from the placenta/cord into the baby and a higher availability of stem cells that help to boast the immune functions.
The practice of cord clamping
The umbilical cord clamping can be divided into immediate (within 15-20 seconds), early (within 60 seconds) and delayed (after 1 minute or cessation of cord pulsation). As research has shown that an immediate cord clamping does not influence postpartum blood loss, the issue to consider now is between early and delayed cord clamping.
There is overwhelming evidence on the benefits of delayed cord clamping. The Cochrane database (2013) has shown that delayed cord clamping is associated with higher haemoglobin level at birth and more iron reserve at 6 months of age. However, these babies are more likely to develop neonatal jaundice, requiring phototherapy. Other potential disadvantages include hypothermia (loss of infant body heat), polycycthemia (excessive infant loading of red blood cells) and delayed mother- child bonding.
This means that the risk of jaundice must be weighed against the risk of iron deficiency. In a society where nutrition status is adequate, iron deficiency is uncommon. Furthermore, effective treatment for neonatal anemia is readily available .
There is no significant increase in risk of postpartum haemorrhage or retained placenta.
The RCOG concluded that the evidence justifies ‘A more liberal approach to delaying clamping of the umbilical cord in healthy term infants … as long as access to treatment for jaundice requiring phototherapy is easily accessible.’
In healthy term babies, the evidence supports deferring clamping of the umbilical cord, as this appears to improve iron stores in infancy. Jaundice may be more common after deferred cord clamping but this management is likely to be beneficial as long as phototherapy for jaundice is available. This assessment of the evidence is concordant with the Cochrane review and the recommendations by NICE.
The delayed in cord clamping may not be universally applicable to all term babies. The risks of neonatal jaundice and phototherapy should be considered against a lower possibility of infant iron deficient anemia, in relation to adequacy of local resources.