12 Effect of Timing of Cord Clamping on Postnatal Hematocrit Values and Clinical Outcome in Term Infants. A Randomized, Controlled Trial

Abstract

Background: Delayed cord clamping at birth increases iron stores in newborns, which correlates with their iron stores at 6, 9 and 12 months of age. This effect may reduce iron deficiency in infancy. However, there are very few randomized studies about the effects of delaying cord clamping on hematological parameters in the newborn and neonatal outcome Objectives: To determine the effect of umbilical cord clamping timing on venous hematocrit (Hct) and clinical outcomes in term neonates within the first month of life.Subjects: Term neonates (>37 weeks of gestation) born to mothers with normal pregnancies and uncomplicated vaginal or caesarean births.Methods: After written informed consent infants were randomized to have the cord clamped either within the first 15 seconds (group 1), or at one minute (group 2), or at three minutes (group 3). An independent observer measured the cord clamping time using a chronometer. When certain unexpected situations occurred (no spontaneous breathing at birth, meconium stained amniotic fluid and nuchal cord) the cord was clamped immediately. The Hct was obtained from the antecubital veins. The analyses were performed in an intention to treat basis. Main outcome measure: venous Hct measured at six hours after birth. Secondary outcome measures: venous hct and bilirubin levels between 24 and 48 h after birth and neonatal outcome.Results: 273 newborns were recruited (group 1= 90, group 2= 91 and group 3 = 92). The median time of cord clamping was 14“ (Q25:7-Q75:15) in group 1; 60” (Q25:60-Q75:61) in group 2 and 180“ (Q25:180-Q75:181) in group 3. Venous Hct (mean) at 6 hours were: 53.5 (SD= 6.9) in group 1; 57.0 (SD= 5.8) in group 2 and 59.4 (SD = 6.1) in group 3. The differences between means were not statistically significant. The rate of infants with Hct >65% was similar between group 1 and group 2 (4.4% and 5.9%, respectively) but was significantly higher in group 3 (14.1%) vs. group 1 (RR=3.1, CI 95%: 1.14-9.02, p= 0.04). All polycythemic infants were asymptomatic and none needed partial exchange transfusion. There were not significant differences between the groups in any of the secondary outcome measures.Conclusions: The cord clamped at least one minute after birth increases Hct levels within a physiological range. Moreover, no harmful effects were observed, thus the practice seems to be safe. Delayed cord clamping should be recommended in term newborns in order to reduce the iron deficiency during infancy.