From the Guidelines
Delayed cord clamping is associated with a higher risk of neonatal polycythemia, but the benefits of delayed cord clamping generally outweigh this risk. The relationship between delayed cord clamping and the development of neonatal polycythemia is supported by the findings of a meta-analysis published in Circulation in 2022 1, which showed that delayed cord clamping at ≥30 seconds compared with early cord clamping at <30 seconds was associated with a higher risk of polycythemia (Hct >65%) in term and late preterm infants. The absolute difference in polycythemia was 50/1000 more infants (30-80 more per 1000) in the delayed cord clamping group compared with the early cord clamping group.
Key Findings
- The meta-analysis found that delayed cord clamping was associated with a higher hematocrit (Hct) within 24 hours after birth, with a mean difference of 3.38% (2.08-4.67) 1.
- The increased blood volume from delayed clamping may elevate the newborn's hematocrit, particularly in situations like maternal diabetes, intrauterine growth restriction, or births at high altitude.
- Most cases of polycythemia are asymptomatic and resolve spontaneously without treatment.
- For symptomatic cases (showing poor feeding, lethargy, or respiratory distress), partial exchange transfusion may be necessary, replacing the infant's blood with normal saline or plasma to reduce viscosity.
Clinical Implications
- Clinicians should monitor infants with risk factors for polycythemia after delayed cord clamping, checking for symptoms and measuring hematocrit levels if indicated.
- Despite the potential complication of polycythemia, the numerous benefits of delayed cord clamping, including improved hemodynamic transition, reduced iron deficiency anemia, and better neurodevelopmental outcomes, make it the standard of care for most deliveries, as recommended by the 2021 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations 1.
- The American Heart Association suggests later (delayed) clamping of the cord at ≥60 seconds for term and late preterm infants born at ≥34 weeks’ gestation who are vigorous or deemed not to require immediate resuscitation at birth, based on a weak recommendation and very low-certainty evidence 1.
From the Research
Relationship Between Delayed Cord Clamping and Neonatal Polycythemia
- Delayed cord clamping has been associated with an increased risk of neonatal polycythemia in some studies 2, 3.
- A study published in JAMA found that delayed cord clamping was associated with an increased risk of asymptomatic polycythemia (RR, 3.82; 95% CI, 1.11-13.21) 2.
- Another study published in the Italian Journal of Pediatrics found that delayed cord clamping at 30-60 seconds resulted in a higher neonatal hemoglobin level on day 3 and an increased rate of neonatal polycythemia, without a higher rate of phototherapy 3.
- However, a study published in PLoS ONE found that delayed cord clamping for ≥ 120 seconds did not increase the risk of polycythemia or neonatal hyperbilirubinemia 4.
- The American College of Obstetricians and Gynecologists recommends delayed umbilical cord clamping for at least 30-60 seconds after birth, citing benefits for term and preterm infants, including improved iron stores and reduced risk of anemia, but notes a small increase in the incidence of jaundice that requires phototherapy in term infants 5.
Factors Influencing the Relationship
- The optimal timing of cord clamping remains uncertain, with different studies recommending different durations of delayed cord clamping 2, 4, 3, 5, 6.
- The risk of polycythemia and other adverse effects may vary depending on the duration of delayed cord clamping and other factors, such as gestational age and mode of delivery 4, 3, 5, 6.
- Further research is needed to fully understand the relationship between delayed cord clamping and neonatal polycythemia, as well as to determine the optimal timing and duration of delayed cord clamping 2, 4, 3, 5, 6.