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Abstract & Commentary
By John C. Hobbins, MD, Professor, Department of Obstetrics and Gynecology, University of Colorado Health Sciences Center, Denver, is Associate Editor for OB/GYN Clinical Alert.
Dr. Hobbins reports no financial relationship to this field of study.
Synopsis: A recent study pitting early milking against late clamping of the umbilical cord shows the same benefit to the infant.
Source: Rabe H, et al. Milking compared with delayed cord clamping to increase placental transfusion in preterm neonates: A randomized clinical trial. Obstet Gynecol 2011;117:205-211.
It has been shown that delayed cord clamping after delivery will increase the blood volume of term and preterm neonates without any apparent downside complications, except for an inability to administer resuscitation to those who need it immediately. Yet, this is not routinely done, according to a survey of obstetricians published in 2009.1 Infants who are born preterm tend to be hypovolemic and anemic, and could benefit the most from an extra bolus of their own blood. Milking the umbilical cord should empty the cord of most of its blood, while theoretically delayed clamping could produce an extra boost by allowing the placenta a chance to give up blood sequestered in the fetal compartment of the placenta.
The authors of a recent paper evaluated the two methods above in those most vulnerable to hypovolemia and anemia, preterm infants born at less than 33 weeks.2 One group was randomly assigned to having umbilical cords milked four times before clamping and another group to having the clamping delayed for more than 30 seconds (without milking), as is the practice in the authors' institution. A host of tests, too extensive to list, were done on these infants, as well as careful documentation of any morbidities. The study was not limited to vaginal births.
The authors found that in the 28 infants randomized to "milking" and the 31 allocated to delayed clamping, the birth weights were comparable (1263 g vs 1237 g), as were gestational ages (29.2 weeks vs 29.5 weeks). Interestingly, the results were also essentially the same for mean hemoglobin (17.3 vs 17.5) and the need for transfusion (15 infants vs 17 infants). Neonatal and maternal morbidities did not differ between groups. Although the cesarean section rate was high in these preterm pregnancies (78% in the milked group and 58% in the delayed group), there were no differences in outcomes between the two methods of delivery.
The only category where there was a difference was at 6 weeks of age, when the mean hemoglobin levels were significantly higher in the milked group.
Other studies have shown that delayed cord clamping results in an increased hemoglobin concentration and blood volume in term and preterm neonates, compared with immediate cord clamping.3,4 The above study suggests that milking the cord four times affords the same benefit in preterm infants, without the need to wait for more than 30 seconds. The fact that red cell volume was increased after 6 weeks with milking is intriguing. The authors postulate that this method releases more stem cells into the infant's circulation, which pays off later in the increased production of red cells.
In summary, as indicated, other studies have shown delayed cord clamping results in increased hemoglobin levels and blood volume in term and preterm neonates, compared with immediate cord clamping. This study suggests that milking the cord four times obtains the same benefit in preterm infants, without wasting precious time before beginning resuscitation. Obviously, in most cases, especially in term pregnancies, the timing of cord clamping is not a big deal. However, if one is interested in drafting delivery protocols, early milking of the cord does seem to afford the same benefit to the infant as delayed clamping.