Further Insights Into Cord Management

Management of the umbilical cord at birth has changed dramatically during the past decade. In both term and preterm infants, the previous standard of immediate early cord clamping has been shown to be inferior to a variety of other umbilical cord management techniques.^1–3 

Delayed (or deferred) cord clamping (DCC) (for anywhere from 30 seconds to minutes of life) is the most extensively tested approach to optimizing placental transfusion. In preterm infants, delayed umbilical cord clamping is associated with improved transitional circulation, improved hematologic measures, and lower incidence of mortality and major disability.^2,4 

However, there are concerns regarding DCC for a critical group of infants: those thought to be in need of immediate resuscitation. Two additional approaches have been suggested in these circumstances: umbilical cord milking (UCM) and DCC with resuscitation with an intact cord.⁵  Umbilical cord milking allows for more rapid placental transfusion by “milking” the umbilical cord in the direction of the infant before clamping the cord. Delayed cord clamping with resuscitation is a more complex intervention, allowing for resuscitation with the cord intact. Although delayed cord clamping with resuscitation has been shown to be feasible for providing placental transfusion in preterm neonates in need of respiratory support,⁶  the relative ease of performing UCM leads many to assume that this approach should be preferred.⁵ 

Early studies of cord milking seemed safe and effective in providing placental transfusion to preterm infants.⁷  Many centers adopted UCM as part of routine practice. A survey of obstetricians and perinatologists in the United States reported 39% provide UCM in healthy term and preterm infants.⁸  However, more recent studies have raised the concern of increased risk of intraventricular hemorrhage (IVH) in extremely preterm infants.^9,10 

In this issue of Pediatrics, Katheria et al report a randomized controlled trial of UCM versus DCC in infants 28 to 32 weeks’ gestation.¹¹  This study is the extension of a previous study in a broader population that was halted early because extremely preterm infants (23 to 27 weeks’ gestation) in the UCM arm had increased risk of IVH compared with infants in the DCC group.¹⁰  Given that the concern for IVH was seen only in the lowest gestational age range, the authors decided to continue enrollment only of mothers at risk for delivering between 28 and 32 weeks’ gestation.

The authors enrolled a total of 1019 infants. For the primary outcome, 7/511 (1.4%) infants randomized to UCM developed severe IVH or died compared with 7/508 (1.4%) infants randomized to DCC (rate difference, 0.01%; 95% confidence interval, –1.4% to 1.4%). Although the authors could not demonstrate noninferiority at a 1% margin, the authors conclude that UCM may be a safe alternative to DCC in preterm infants born at 28 to 32 weeks’ gestation who require resuscitation.

The authors discuss several limitations of the trial, including not recalculating the sample size to account for the lower incidence of severe IVH and/or death in the more mature infants being enrolled. The recalculated sample size suggests that a threefold increase in enrollment would be required to avoid missing a real difference in the 2 interventions.

The authors’ conclusions are in keeping with the recommendations of authoritative groups such as International Liaison Committee on Resuscitation, who state that UCM is “a reasonable alternative to deferring cord clamping (weak recommendation, moderate-certainty evidence), in infants born between 28 and 34 weeks’ gestational age, not requiring immediate resuscitation.”¹² 

Although the study seems to support these recommendations, it is worth taking a step back to understand the underpinning of the trial and our approach to UCM. Why is UCM “noninferior”? It certainly is easier to accomplish quickly and without changes in equipment or processes. However, it assumes that there is pressing need to deliver the preterm infant to an open warmer where resuscitation can begin. This argument falls prey to a series of misbeliefs about the ability of the preterm infant to make an adequate transition. There are lessons we learned from our evolving approach to respiratory management in the delivery room, where less invasive approaches to support are clearly gaining ground. In studies that have examined our approach to “resuscitation,” preterm infants frequently receive positive pressure ventilation or other respiratory support even though most were breathing and no attempt was made to assess heart rate.^13,14 

Does UCM in preterm infants without significant signs of fetal distress feed into this paradigm? Is our assumption that all these infants need immediate resuscitation as opposed to allowing for a more physiologically appropriate transition, potentially causing more harm than good? Certainly, Katheria and colleagues have shown that we can achieve effective placental transfusion in moderately preterm infants with umbilical cord milking, but other more subtle outcomes, such as parental/maternal attitudes and experience are missing from these analyses. The authors of this study clearly understand the commitment to examining all the nuances of cord management and are committed to follow-up of the infants in this study as well as leading a variety of other studies evaluating different cord management techniques. We frequently make the mistake of losing impetus to continue trials once some, but not all, of the answers have emerged. We can thank these and other investigators for continuing to evaluate these issues that surely affect the health of every newborn worldwide.

DCC

delayed cord clamping

IVH

intraventricular hemorrhage

UCM

umbilical cord milking