Immediate clamping of the umbilical cord at birth has been associated with short- and long-term problems in newborns. Early clamping (within one minute after birth) can reduce the amount of umbilical cord blood transferred to the baby by more than 50 percent. Research shows that delaying clamping produces higher hematocrit and hemoglobin levels (more red blood cells, less anemia), healthier blood pressure, and improved heart rate and breathing in newborns. Polycythemia and hyperbilirubinemia are risks associated with delaying cord clamping, but studies find these risks extremely low.
Detrimental effects of early cord clamping
Nurse midwife Judith Mercer has investigated cord clamping in several studies and authored a 2001 literature review that points to some long-term harmful effects associated with early cord clamping. These include infant anemia, childhood mental disorders, and hypoxic ischemic brain damage.
Benefits of delaying for preterm infants
A 1993 study measured the effects of umbilical cord clamping on preterm infants. The investigators found that holding the newborn at about eight inches below the vaginal opening for 30 seconds before clamping the cord (sometimes referred to as “milking” the cord) improved bilirubin levels, decreased red cell transfusion requirements, and lowered the infant’s dependence on supplemental oxygen.
Lasting benefits of delaying for full-term infants
A 2007 study examined the timing of umbilical cord clamping in full-term babies. The conclusion was that delaying clamping for at least two minutes after birth improved the babies’ hemacrit and iron status (stored iron), and that these benefits extended two to six months into infancy. Similar results were found in a large 2004 study on 476 newborns.
La Leche League’s The Womanly Art of Breastfeeding cites this 2004 literature review. The authors conclude that delayed cord-clamping increases hemoglobin concentration in babies at 2 to 3 months, reduces the risk of anemia (especially in babies with anemic mothers), and does not increase the risk of complications.
Benefits of delaying for breastfed babies
In a 2006 study published in The Lancet, delaying cord clamping by two minutes resulted in increased iron stores in the babies at six months by 27 to 47 milligrams. And this effect was significantly greater in breastfed babies not receiving iron-fortified milk or formula, in babies whose mothers had low ferritin (a protein that stores iron), and in babies who weighed between 5.5 pounds and 6.5 pounds at birth.
A natural stem cell transplant
In a 2010 review article titled “Mankind’s first natural stem cell transplant,” researchers point out that a few types of important stem cells are transferred through the cord blood and argue that this greatly increases the benefits of delaying cord clamping.
Most research on the timing of cord clamping emphasizes the benefits of delaying. Only a few studies focus on the dangers of immediate clamping. From the studies cited in this article, one could conclude that the detrimental effects of early cord clamping are the loss of the benefits associated with delayed clamping, and these effects are significant and lasting.
Discuss this procedure with your birth attendant (obstetrician, midwife, or doula) and include your preference in your birth plan. As Ina May Gaskin, CPM, writes in her Guide to Childbirth, if you prefer to delay cord clamping, “the evidence is on your side.”
Amy Mitchell is a freelance writer in Jacksonville, Florida.
Additional References:
American Academy of Pediatrics, Evidence-Based Review of Science for Cord Clamping, http://www.aap.org/nrp/pdf/030B.pdf
World Health Organization, Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes (Reproductive Health Library Commentary), http://apps.who.int/rhl/pregnancy_childbirth/childbirth/3rd_stage/cd004074_abalose_com/en/index.html
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