Thirteen years ago, I wrote an article in the Townsend Letter suggesting that many infants could benefit if obstetricians would adopt a practice that is common among midwives – delaying the clamping of the umbilical cord after the baby is born. More than a decade later, the mainstream obstetrical community has finally acknowledged the importance of giving newborns extended access to the placental blood supply.
At the time a baby is born, the placenta contains a relatively large amount of blood. If the cord is allowed to remain open, much of this blood is delivered to the baby through the umbilical cord. The volume of this placental "transfusion" amounts to approximately 40 ml of additional blood per kg of body weight.1 This blood provides about 75 mg of extra iron, an amount sufficient to meet the baby's iron needs for more than three months. Iron deficiency is one of the most common nutritional problems during the first year of life. In addition to being a component of hemoglobin, iron is essential for brain development. A deficiency of iron during this critical period can result in impaired myelination in the central nervous system2 and permanent impairment of brain function.3 In addition, cord blood is rich in stem cells, which are capable of differentiating into oligodendrocytes (which play a role in myelin formation).2 Moreover, the delivery of highly oxygenated fetal hemoglobin from the placenta to the baby may have a favorable effect on the infant's health in the early postnatal period.
Midwives have traditionally delayed cord clamping until the cord stops pulsing, or for at least three minutes after delivery. Obstetricians, on the other hand, have traditionally clamped the cord almost immediately, so that the baby can be assessed, weighed, and readied for whatever emergency interventions might become necessary. The reluctance of obstetricians to delay cord clamping has also been due to a concern that doing so could increase the risk of neonatal hyperbilirubinemia. When I wrote my article in 2006, there was evidence that delaying cord clamping can decrease the prevalence of iron deficiency and iron-deficiency anemia at six months of age.1 However, as of 2012, the official position of the American College of Obstetricians and Gynecologists was that the evidence "is insufficient to confirm or refute the potential for benefits from delayed umbilical cord clamping in term infants…."4
Since that time, a number of studies have provided additional evidence about the benefits of delaying cord clamping. Some of those studies are described below.
In a study of 540 late preterm and term infants born in Nepal who were at high risk of iron deficiency, delaying cord clamping significantly decreased the prevalence of anemia and significantly improved measures of neurodevelopment at 12 months of age.5,6
Seventy-three infants born in the US at term were randomly assigned to delayed cord clamping (DCC; mean, 2.87 minutes) or immediate clamping (ICC; mean, 28 seconds). In patients who underwent cesarean delivery, milking of the cord five times was the proxy for DCC. At four months of age, the mean serum ferritin concentration was significantly higher in the DCC group than in the ICC group (96.4 vs. 65.3 ng/dl; p = 0.03). In addition, infants in the DCC group, as compared with those in the ICC group, had greater myelin content in brain regions associated with motor, visual, and sensory processing/function (indicating better functional development of the brain).7
One hundred thirteen small-for-gestational-age infants born in India at 35 weeks of gestation or later were randomly assigned to delayed cord clamping (DCC; at 60 seconds) or early cord clamping (ECC; immediately after birth). At three months of age, the median serum ferritin level was significantly higher with DCC than with ECC (86 vs. 50.5 ng/ml; p = 0.01). Fewer infants had iron deficiency with DCC than with ECC; (23.6% vs. 47.7%; p = 0.03).The proportion of infants with polycythemia was significantly higher with DCC (41.8% vs. 20.6%; p = 0.01), but there was no difference in the proportion of infants with symptomatic polycythemia or in those who required partial exchange transfusions.8
Experts Now Recommend Delaying Cord Clamping
In January 2017, the Committee on Obstetric Practice of the American College of Obstetricians and Gynecologists issued a new set of recommendations regarding the timing of umbilical cord clamping. The report stated:
Delayed umbilical cord clamping appears to be beneficial for term and preterm infants. In term infants, delayed umbilical cord clamping increases hemoglobin levels at birth and improves iron stores in the first several months of life, which may have a favorable effect on developmental outcomes. There is a small increase in jaundice that requires phototherapy in this group of infants. Consequently, health care providers adopting delayed umbilical cord clamping in term infants should ensure that mechanisms are in place to monitor for and treat neonatal jaundice. In preterm infants, delayed umbilical cord clamping is associated with significant neonatal benefits, including improved transitional circulation, better establishment of red blood cell volume, decreased need for blood transfusion, and lower incidence of necrotizing enterocolitis and intraventricular hemorrhage…. Given the benefits to most newborns and concordant with other professional organizations, the American College of Obstetricians and Gynecologists now recommends a delay in umbilical cord clamping in vigorous term and preterm infants for at least 30-60 seconds after birth.9
These new recommendations seem to validate (albeit belatedly) the wisdom of Mother Nature. That is, if the cord continues to pulse for a period of time after delivery, it may be doing so for a reason; and it may be unwise to interfere with the placenta's attempt to give the baby one final gift. There is still no agreement on the optimal timing of cord clamping, which has varied between one minute and five minutes in various studies. There seems to be something inherently logical about the midwives' practice of waiting (if possible) until the cord has stopped pulsing.
Alan R. Gaby, MD
1. Chaparro CM, et al. Effect of timing of umbilical cord clamping on iron status in Mexican infants: a randomised controlled trial. Lancet. 2006;367:1997-2004.
2. Rao R, Bora R. Timing of umbilical cord clamping and infant brain development. J Pediatr. 2018;203:8-10.
3. Lozoff B, et al. Long-term developmental outcome of infants with iron deficiency. N Engl J Med. 1991;325:687-694.
4. Committee on Obstetric Practice, American College of Obstetricians and Gynecologists. Committee Opinion No.543: Timing of umbilical cord clamping after birth. Obstet Gynecol. 2012;120:1522-1526.
5. Kc A, et al. Effects of delayed umbilical cord clamping vs early clamping on anemia in infants at 8 and 12 months: a randomized clinical trial. JAMA Pediatr. 2017;171:264-270.
6. Rana N, et al. Effect of delayed cord clamping of term babies on neurodevelopment at 12 months: a randomized controlled trial. Neonatology. 2018;115:36-42.
7. Mercer JS, et al. Effects of delayed cord clamping on 4-month ferritin levels, brain myelin content, and neurodevelopment: a randomized controlled trial. J Pediatr. 2018;203:266-272.e2.
8. Chopra A, et al. Early versus delayed cord clamping in small for gestational age infants and iron stores at 3 months of age – a randomized controlled trial. BMC Pediatr. 2018;18:234.
9. Committee on Obstetric Practice. Committee Opinion No. 684: Delayed umbilical cord clamping after birth. Obstet Gynecol. 2017;129:e5-e10.