Discussion Questions

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  What was the study design?

  
  
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  What interventions were under investigation?

  
  
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  What outcomes were measured?

  
  
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  What guidelines exist for reporting studies?

  
  
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  What were the results of this study?

  
  
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  How do the results pertain to clinical practice?

Introduction

Optimal timing of cord clamping is a subject that has garnered much interest recently. In December, 2012, the American Congress of Obstetricians and Gynecologists (ACOG), with the American Academy of Pediatrics (AAP), recommended delayed cord-clamping for preterm infants—though not for term infants. Systematic reviews of the available data revealed that intraventricular hemorrhage was reduced by nearly 50% in preterm infants when cord clamping was delayed. In term infants, delayed clamping was associated with increased levels of hemoglobin and ferritin, but increased rates of hyperbilirubinemia were also noted. A new study examines cord milking, active movement of cord contents toward the infant.

George A. Macones, MD, MSCE, Associate Editor

Introduction

Optimal timing of cord clamping is a subject that has garnered much interest recently. In December, 2012, the American Congress of Obstetricians and Gynecologists (ACOG), with the American Academy of Pediatrics (AAP), recommended delayed cord-clamping for preterm infants—though not for term infants. Systematic reviews of the available data revealed that intraventricular hemorrhage was reduced by nearly 50% in preterm infants when cord clamping was delayed. In term infants, delayed clamping was associated with increased levels of hemoglobin and ferritin, but increased rates of hyperbilirubinemia were also noted. A new study examines cord milking, active movement of cord contents toward the infant.

George A. Macones, MD, MSCE, Associate Editor

Study Design

Macones: Thank you for joining me to discuss this article on cord milking at delivery. I believe it is a very timely study since, as you know, ACOG, with the assistance and subsequent endorsement of the AAP recently published a Current Opinion that advised delayed cord clamping for preterm infants. Studies indicated that the technique was associated with a reduced rate of intravascular hemorrhage, as well as a reduced need for transfusion in this population. The opinion pointed out that the role of cord milking, as opposed to just delayed cord clamping, was an area that required more research. Thus, I thought this was a very timely study. The authors performed a very tidy clinical trial comparing cord milking to routine care.

Macones: What did you think of the study design?

Cahill: As you mentioned, the authors performed a clinical trial, which of course is the gold standard for an efficacy study. I really thought this was an appropriate design—there is enough information out there to have made a clinical trial necessary. An observational study would not have been particularly helpful at this point.

Macones: Any comments on the inclusion and exclusion criteria?

Cahill: The inclusions and exclusions seemed very reasonable to me. Patients were included if they delivered at 35 weeks or beyond. Subjects were excluded if they had an Rh-negative mother, a short umbilical cord (<25 cm), a major congenital anomaly, hydrops fetalis, or limpness at birth. Infants who were 1 of a set of multiples were excluded, as were those who were sluggish after exposure to meconium-stained amniotic fluid or were delivered via cesarean section because they were compromised. Babies born of pregnancies marked by cord prolapse, placenta previa, placental abruption, or cord abnormalities were also excluded.

Macones: The criteria do seem very reasonable for a study of near-term infants. An interesting criterion was the exclusion of infants due to fetal compromise. Some believe that these infants, especially after preterm birth, are most likely to benefit from the extra blood associated with milking or delayed clamping. But for this study population, I thought the exclusion made sense.

Macones: Can you talk about the interventions and main outcomes?

Odibo: Sure. The interventions are well described, and in fact, the researchers provide a link to a video of cord milking ( http://www.videos.med.usyd.edu.au/unitube/videos/file19 ). The standard treatment arm essentially underwent cord clamping as we do here at Washington University. In control subjects, the cord was clamped within 30 seconds of birth and cut near the umbilicus. For the cord milking, I would suggest that people watch the video but it seems like a long segment of cord is left attached to the baby, and then it is milked pretty quickly. It almost looked like a bolus could be obtained from that procedure. In this study, the cord was cut at about 25 cm from the umbilicus within 30 seconds of birth and then milked 3 times at a speed of 10 cm/sec while the baby was under a radiant warmer. The primary outcomes were hemoglobin and serum ferritin levels at 6 weeks of age. Secondarily, the authors assessed neonatal hemodynamic parameters and other clinical parameters, such as respiratory distress syndrome and jaundice, in the first 2 days of life. The sample size was based on the primary outcome, and the authors aimed to detect an average increase of 1 g/dL in hemoglobin among infants whose cords were milked when compared with controls. They inflated the sample size by 15% because they anticipated that some 10-15% might be lost to follow-up, which I thought was quite sensible—in general, I thought the sample size calculation was excellent.

Macones: Initially, I was surprised that no maternal outcomes were measured, especially since some investigators have been concerned about postpartum hemorrhage with delayed cord clamping. But upon watching the video of how milking is done, I became much less concerned. Macones: Does anybody have any comments about the analysis?

Odibo: Not really. This is a clinical trial so nothing fancy is needed. The authors appropriately used standard bivariate analytic techniques.