Review
Promoting physiologic transition at birth: Re-examining resuscitation and the timing of cord clamping

https://doi.org/10.1016/j.siny.2013.08.008Get rights and content

Summary

Delayed clamping of the umbilical cord is recommended for term and preterm infants who do not require resuscitation. However, the approach to the newly born infant with signs of fetal compromise, prematurity and extremely low birthweight, or prolonged apnea is less clear. Human and experimental animal data show that delaying the clamping of the umbilical cord until after the onset of respirations promotes cardiovascular stability in the minutes immediately after birth. Rather than regarding delayed cord clamping as a fixed time period before resuscitation begins, a more physiologic concept of transition at birth should encompass the relative timing of onset of respirations and cord occlusion. Further research to explore the potential benefits of resuscitation with the cord intact is needed.

Introduction

A 29-week infant is delivered by cesarean section with epidural anesthesia for progressive cervical dilation despite tocolysis and breech presentation. The amniotic fluid is clear at intraoperative rupture of membranes. At birth the infant appears consistent with estimated gestation, her arms are flexed, but she does not cry. The obstetrician places the infant on a warm towel, covers her body with a second towel, and holds the head straight in a sniffing position. The infant takes a breath between 10 and 15 s. The obstetrician provides gentle tactile stimulation but does not clear the airway, as no secretions are visible. Occasional spontaneous respirations continue, and by 45 s the infant has sustained respirations. The cord is clamped at 60 s. The baby is breathing and moving actively on arrival at the warmer. Continuous positive airways pressure (CPAP) is applied with 30% oxygen. The heart rate is >100 bpm.

The same 29-week infant is delivered by cesarean section. At birth the infant appears consistent with estimated gestation, her arms are flexed, but she does not cry. The obstetrician immediately clamps and cuts the cord. The baby is apneic and motionless on arrival at the warmer. CPAP is applied with 30% oxygen. The heart rate by cord palpation is 70 bpm. Positive-pressure ventilation is begun with T-piece. Saturations fail to meet time-specific targets and oxygen is increased to 60%. At 3 min the baby begins to breathe spontaneously and heart rate is consistently >100 bpm.

Current neonatal resuscitation guidelines recommend a rapid assessment at the moment of birth to gauge the likelihood of need for further resuscitation. The three rapid assessment questions include: Is the baby term? Is the baby breathing? Is there good muscle tone? If the answer to any question is ‘no’, the infant is carefully evaluated and provided the initial steps of resuscitation: warmth, drying, clearing the airway as necessary and stimulation to breathe. Breathing and heart rate are evaluated next and cycles of re-evaluation (breathing, heart rate, saturation) guide progress through the resuscitation algorithm [1]. The 2010 International Liaison Committee on Rescuscitation (ILCOR) Consensus on Science also states that ‘Cord clamping should be delayed for at least 1 min in babies who do not require resuscitation…. Evidence is insufficient to recommend a time for clamping in those who require resuscitation [2].’

Analyzing the first case scenario according to the rapid assessment questions highlights that this preterm baby who is not breathing, but has good muscle tone, needs ongoing evaluation and the initial steps of warmth, clearing the airway as necessary, and stimulation to breathe. When the initial steps are provided with the umbilical circulation intact, the infant establishes regular spontaneous respirations and needs only CPAP and a low concentration of supplemental oxygen. When the umbilical cord is clamped immediately to move the newly born infant to an open warmer for the initial steps, the baby remains apneic and has a low heart rate, prompting positive-pressure ventilation. Higher oxygen concentrations are needed to achieve time-specific saturation targets, and regular spontaneous breathing and normal heart rate are achieved only after a few minutes of positive-pressure ventilation.

Section snippets

Background: The circular argument

Did the infant in the second case scenario need resuscitation or did that infant suffer from an interruption of physiologic transition at birth? For this infant, and likely for many others, interruption of physiologic transition at birth by immediate cord clamping can result in the vital sign indicators that call for neonatal resuscitation interventions. Barcroft [3] reported that bradycardia occurs in the fetus in response to umbilical cord occlusion. In the newly born infant who has not yet

Synopsis of the physiology of placental transfusion

During fetal life the feto-placental blood volume distribution changes with increasing gestation; early in development, a larger proportion of the blood volume resides in the placenta, but as gestation advances, more circulating volume is present in the fetus [6]. In the minutes after birth, transfer of blood continues from placenta to the newly born infant through the patent umbilical vein. This transfer occurs most rapidly in the first minute, but continues until constriction of the umbilical

The condition of immediate cord clamping before onset of respirations

Several historical studies illuminate the condition of immediate cord clamping before the onset of respirations. Lind, Peltonen, and colleagues presented cineradiographs of the aeration of the lung at birth during the Second Scandinavian Summer Meeting of Biochemistry, Medical Chemistry, Pharmacology and Physiology in Turku, Sweden in 1959.

Among early clamped infants, those clamped prior to the first breath can be distinguished as a separate group…. If the umbilical cord is tied prior to the

The condition of cord clamping delayed until after onset of respirations

Many historical sources advocate for delayed clamping until after onset of respirations or until cord pulsation ceases. Erasmus Darwin, the British physician, philosopher, and grandfather of Charles Darwin, wrote in 1801,

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

A refined paradigm: Delay of umbilical cord clamping until establishment of respirations

Promoting a more physiologic transition at birth by delaying umbilical cord clamping until respirations are established offers numerous theoretical benefits for the premature or mildly depressed infant. Virtually every organ system is impacted by the placental transfusion (Box 1), and promoting physiologic transition could potentially reduce the acuity of care needed and the incidence of complications. In low- and middle-income countries, the value of bundling interventions such as antenatal

Umbilical cord milking or stripping as an alternative to delayed cord clamping

Despite the benefits of delayed cord clamping, there are some practical limitations associated with the delay itself. Delay in cutting of the cord might interfere with management of profuse bleeding in the mother and thus endanger the mother. Second, as previously noted, it may be difficult to institute effective resuscitation of the newborn when the baby is still at the perineum or on the operative field. Finally, VLBW infants might develop hypothermia because of difficulty with thermal

Cord stripping/milking, and circulatory changes at birth

The effect of milking the cord at birth on blood volume was reported by Colozzi in 1954, where he stated

I have seen several infants with asphyxia pallida who were very pale and listless, with a rapid pulse and a very weak cry; with gentle, slow, methodical cord stripping, they were transformed within a few minutes to ruddy, lustily-crying infants [43].

The increase in blood volume to the lungs associated with cord stripping has also been documented with recording of electrocardiographic changes;

Cord milking and haemoglobin or need for transfusion

Many studies have indirectly measured the effect of umbilical cord milking through looking at red blood cell mass, levels of haemoglobin and need for blood transfusion. They have compared it with early [42], [43], [45], [47], [49], [51], [53], [54] and delayed [43], [49], [51], [52] clamping of the cord in both preterm and term infants. Umbilical cord milking was associated with higher red blood cell mass and haemoglobin in both term [42], [43], [47], [49], [53], [54] and preterm infants [45],

Gaps in knowledge and areas for research

Physiologic data on the importance of the sequence of pulmonary expansion before clamping of the umbilical cord have changed the resuscitation paradigm from a simple time interval for delay in clamping to an ordered series of interventions. First, in order to accurately interpret neonatal stabilization and resuscitation, there is a need to note and record the time to onset of respirations and time to umbilical cord clamping in all deliveries, and especially in infants who will participate in

Conflict of interest statement

None declared. Both Dr. Niermeyer and Dr. Velaphi are neonatal evidence evaluation reviewers for the International Liaison Committee on Resuscitation.

Funding sources

None.

Practice points

  • •

    Delay of umbilical cord clamping until after the onset of respirations promotes a smoother cardiopulmonary transition after birth.

  • •

    Umbilical cord clamping before onset of respirations results in decreased cardiac output, bradycardia, and fluctuations in cerebral blood flow.

  • •

    Time to onset of respirations and time to umbilical cord clamping should be recorded for all births, and should be considered important covariates in research on neonatal outcomes.

  • •

    Cord milking may provide

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