What are the effects on the central nervous system (CNS) of clamping and cutting the umbilical cord after delivery of the head and before delivery of the fetal body?

Effects of Clamping and Cutting Umbilical Cord After Head Delivery on CNS

Clamping and cutting the umbilical cord after delivery of the head but before delivery of the fetal body is not recommended due to potential adverse effects on the central nervous system, including increased risk of intraventricular hemorrhage and compromised neurodevelopment.

Physiological Implications

Cutting the cord after head delivery but before complete birth interrupts critical physiological processes:

1. Disruption of Placental Transfusion

   • Prevents the normal transfer of blood volume from placenta to infant
   • Reduces neonatal hemoglobin levels and iron stores 1
   • Compromises establishment of adequate circulatory volume

2. Impaired Cardiovascular Transition

   • Disrupts the ordered physiological transition from fetal to neonatal circulation 2
   • Prevents maintenance of left ventricular filling and output critical for cerebral perfusion 3
   • Creates hemodynamic instability during a vulnerable period

CNS-Specific Risks

Increased Risk of Intraventricular Hemorrhage (IVH)

• Delayed cord clamping reduces the risk of any grade IVH (RR 0.83,95% CI 0.70 to 0.99) 4
• Early cord clamping before complete delivery may increase IVH risk due to:
  • Sudden hemodynamic fluctuations
  • Reduced cerebral blood flow
  • Inadequate blood volume for proper CNS perfusion

Neurodevelopmental Concerns

• Delayed cord clamping is associated with improved neurodevelopmental outcomes 3, 1
• Early clamping after head delivery may lead to:
  • Iron deficiency, which is associated with impaired motor development, behavioral problems, and cognitive delays 3
  • Compromised oxygenation during the critical transition period 5

Current Guidelines and Recommendations

The 2024 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science strongly recommends:

• For preterm infants <37 weeks: Defer cord clamping for at least 60 seconds 3
• For term infants: Delay cord clamping for at least 30-60 seconds 1

These recommendations are based on high-certainty evidence showing reduced mortality with deferred cord clamping compared to immediate cord clamping 3.

Special Considerations

Resuscitation Needs

• If immediate resuscitation is required, the cord should not be clamped between head delivery and body delivery
• Current recommendations suggest providing initial resuscitation steps with the cord intact when possible 3

Physiological Approach

• Optimal cord management should be based on physiological endpoints rather than arbitrary time points 2
• Cord clamping should ideally occur after establishment of respiration and pulmonary blood flow 2

Clinical Practice Algorithm

1. Normal Delivery

   • Allow complete delivery of the infant
   • Delay cord clamping for at least 30-60 seconds (term) or 60 seconds (preterm)
   • Place infant at or below the level of the placenta during this time

2. If Head Delivers but Body is Delayed

   • Maintain cord integrity
   • Focus on delivering the body without cord manipulation
   • Only consider cord clamping if maternal/fetal emergency requires immediate intervention

3. Emergency Situations

   • If resuscitation is needed, prioritize complete delivery when possible
   • Consider cord milking as an alternative to immediate clamping for infants 28-36 weeks 3
   • Avoid intact cord milking in infants <28 weeks due to increased risk of severe IVH 3

Conclusion

Clamping and cutting the umbilical cord after delivery of the head but before delivery of the body interrupts critical physiological processes and may increase the risk of adverse CNS outcomes, including intraventricular hemorrhage and impaired neurodevelopment. Current evidence strongly supports delaying cord clamping until after complete delivery of the infant.