The effect of early and late umbilical cord clamping on neonatal
A Jahazi1, M Kordi2, NB Mirbehbahani3and SR Mazloom4
1Midwifery Department, Gorgan Branch, Islamic Azad University, Golestan, Iran;2Midwifery Department, Mashad College of
Nursing-Midwifery, Khorasan Razavi, Iran;3Neonatology Department, Gorgan University of Medical Sciences, Golestan, Iran;
4Midwifery Department, Mashad College of Nursing-Midwifery, Khorasan Razavi, Iran
Objective: To compare the effect of early and late cord clamping (LCC) on
neonatal hematocrit at 2 and 18h of life.
Study Design: In this double-blind randomized trial, 64 healthy full-
term vaginally born neonates were randomly allocated to either early
(30s) or late (3min) umbilical cord clamping. During the interval
between delivery and cord clamping, the attendant held the neonate
supine at the level of the introitus. Neonatal venous hematocrit was
measured at 2 and 18h of life.
Result: Neonatal hematocrit at 2h of life (61±4.9 vs 61.6±4.5%) and
18h of life (56.9±4.1 vs 56.2±3.9%) was not significantly different
between the two groups. This was also true for neonatal polycythemia
(20 vs 23.5%). In the LCC group, placental residual blood volume (PRBV)
was 39.5% lower and estimated neonatal blood volume (ENBV) was 7.1%
higher than that in the early cord clamping (ECC) group (P<0.001).
Conclusion: Late cord clamping does not lead to a significant difference
in the hematocrit level of the neonate or neonatal polycythemia, but is
associated with a significant increase in ENBV and a significant decrease
in PRBV. Further trials should examine the effect of delaying cord
clamping for a longer period of time or changing the position that the
neonate is held in to determine whether these variations result in more
clinically significant results.
Journal of Perinatology (2008) 28, 523–525; doi:10.1038/jp.2008.55;
published online 3 July 2008
Keywords: early cord clamping; late cord clamping; hematocrit;
Early cord clamping (ECC) vs late cord clamping (LCC) in
newborn infants has been the subject of debate and dialog for
many years. In 1801, Erasmus Darwin wrote, ‘Another thing very
injurious to the child is tying and cutting the navel-string too soon;
which should always be left till the child has not only repeatedly
breathed but also till all pulsation in the cord ceases. As otherwise,
the child is much weaker than it ought to be, a part of the blood
being left in the placenta, which ought to have been in the child.’1
ECC at birth has become a routine procedure. This may deprive
neonates of significant blood volume and can cause neonatal
short-term and long-term potential problems such as respiratory
distress, anemia and cerebral pulsy and mental retardation.2,3
Benefits associated with delayed clamping include better
cardiopulmonary adaptation, prevention of respiratory distress,
prevention of anemia in infancy and increased duration of early
breastfeeding.4–6The concerns regarding delayed cord clamping
include the possibility of precipitating polycythemia, hyperviscosity,
hyperbilirubinemia and transient tachypnea of the newborn.4
Placental transfusion can provide the infant with 30%
additional blood volume and up to 60% more red blood cells.7
Adequate blood volume is necessary for suitable oxygen transport
and organ and tissue perfusion in the newborn.8The magnitude of
placental transfusion depends in part on the effects of gravity and
the timing of cord ligation. Most of the placental transfusion takes
place in the first 3min after birth; 50 to 70% of the volume
transfuses in the first minute.1
Previous studies regarding the delayed cord clamping have had
mixed results. Several did not show a significant difference in
hematocrit of neonates between the ECC and LCC groups,2,9
whereas others demonstrated a marked rise hematocrit during the
first hours of neonatal life in the LCC group. No prior studies have
reported findings about polycythemia in these neonates.1,10
The question of early versus late umbilical cord clamping is still
unanswered. This study was designed to compare the effect of early
and late umbilical cord clamping on neonatal hematocrit.
This is a double-blind randomized clinical trial conducted between
7 October 2002 and 9 February 2003, in Dezyani hospital of
Gorgan (a city located in the north of Iran). Women with
Received 22 May 2007; revised 21 February 2008; accepted 7 April 2008; published online 3 July
Correspondence: A Jahazi, Midwifery Department, Islamic azad university, gorgan branch,
Daneshgah, PO Box: 715, Gorgan, Golestan 98, Iran.
Journal of Perinatology (2008) 28, 523–525
r 2008 Nature Publishing Group All rights reserved. 0743-8346/08 $30
uncomplicated pregnancies, delivering between 38 and 42 weeks
gestational age by last menstrual period or first or second trimester
ultrasound, undergoing unmedicated deliveries were eligible for
enrollment. Infants with 1- or 5-min apgar scores less than 7,
those diagnosed with congenital anomalies, or who were small for
gestational age (<10 percentile) or large for gestational age (>90
percentile) were excluded from the analysis. Infants with cord
blood hematocrit <40 or >65 were also excluded.
Infants were randomized immediately before vaginal delivery to
either ECC or LCC groups by one coin. The umbilical cord was
clamped 30s and 3min after birth in the ECC and LCC group,
respectively. A midwife controlled this time by a stopwatch, starting
with complete delivery of the neonate. During this time, the
attendant held the neonate supine at the level of the introitus. In
the LCC group, the attendant placed the neonate on a table at the
level of the introitus, dried and wiped him/her with a warm sterile
A unit of 1ml blood was collected from umbilical vein into
ethylene diamie tetraacetic acid (1.2mgml?1) immediately after
cord clamping before delivery of the placenta. A unit of 1ml
antecubital blood was collected at 2 and 18h (±10min) after
birth. Hematocrit was measured by the microhematocrit method.
Placental residual blood volume (PRBV) was measured according
to the method described by Yao et al.11: as soon as the infant was
born and the umbilical cord has been clamped and cut at the
appropriate time, a sterile 250ml graduated cylinder was utilized to
collect the PRBV by releasing the clamped end of the cord, whereas
the placenta was still in uterus. After an initial rapid drainage of
blood, there was intermittent dripping of blood in association with
each uterine contraction felt in the abdomen. The cord was again
clamped when the placenta was being delivered. The delivered
placenta was cleaned of maternal blood clots on its surfaces and
placed in a plastic funnel 20cm in diameter at a height of 35cm
to allow further drainage of blood for another 15min. The cord
was stripped gently once. The placenta was then weighed.
Estimated neonatal blood volume at birth (ENBV) was calculated
as the difference between an assumed total feto–placental blood
volume of 115mlkg?1and the measured PRB.V.10Oxytocin
(10IU) was injected to all mothers intramuscularly after cord
ligation. The clinical manifestations of polycythemia, including
tachypnea, cyanosis, tachycardia, lethargy, irritability, tremors,
vomiting and poor feeding12were assessed when the infants were
seen for blood sampling and at 5 days after birth. All infants were
The study was approved by the Mashad University of Medical
Sciences Research Committee. Written informed consent was
obtained from the parent before enrollment.
We calculated that a sample size of 23 infants in each group was
needed to detect an increase in the mean hematocrit by 6.4% with
a power of 90% and confidence level of 95%. The data were
analyzed by using SPSS (v 13.0) for windows. The Student’s t-test
for two independent samples was used to compare the mean values
in the ECC and LCC groups. For nonparametric variables, w2and
Mann–Whitney tests were used.
A total of 30 infants were randomized to the ECC group and 34
infants to the LCC group. In the LCC group, PRBV was 39.5% lower
and ENBV was 7.1% higher than that in the ECC group. Table 1
shows some of the maternal and neonatal characteristics in the
Cord blood hematocrit, neonatal hematocrit at 2h of life and
neonatal hematocrit at 18h of life did not significantly differ
between the two groups. Hematocrit rose markedly in both groups
at 2h of life, then decreased slowly during 18h of life, but did not
reach the cord blood hematocrit value (Table 2).
Table 1 Maternal and neonatal characteristics
Variables LCC ECC
Maternal age (years)
Cervical dilation (cm)
Duration of the third stage of
Gestational age (weeks)
Birth weight (g)
1-min Apgar score
5-min Apgar score
Abbreviations: ECC, early cord clamping; ENBV, estimated neonatal blood volume; LCC,
late cord clamping; PRBV, placental residual blood volume.
cThe range is shown in parenthesis for 1- or 5-min Apgar score.
Table 2 Hematocrit values (%)
0 (Cord blood)
2h of life
18h of life
Abbreviations: ECC, early cord clamping; LCC, late cord clamping.*Mean±s.d.
aWhen compared with the ECC group of same age.
cP<0.001 when compared with values at birth.
dP<0.001 when compared with values at 2h of life in each group.
Early and late cord clamping
A Jahazi et al
Journal of Perinatology
No infant developed clinical manifestations of polycythemia at
2h, 18h and 5 days after birth. A total of 21.9% of neonates
developed asymptomatic polycythemia at 2h of life. There was no
significant difference in asymptomatic polycythemia at 2h of life
between the study groups. No infant developed asymptomatic
polycythemia at 18h of life (Figure 1).
We sought to compare the effect of early and late umbilical cord
clamping on neonatal hematocrit. In this study, neonatal
hematocrit and polycythemia did not significantly differ between
the two groups. No infant developed clinical manifestations of
polycythemia. In the LCC group, PRBV was lower and ENBV was
higher than that in the ECC group. Cord clamping after 3min of
birth resulted in a placental transfusion of about 20ml.
Our results confirm previous reports of the effect of ECC and LCC
on PRBV2,9In contrast to our results, Nell et al.13have previously
reported that neonates delivered according to Leboyer childbirth who
undergo cord clamping 3min after birth had significantly higher
hematocrits than those with cord clamping 10s after birth. One
possible explanation for this discrepancy is the difference in the
timing of cord clamping in the ECC group. In previous studies, in
the ECC group, the cord is clamped approximately 10s after birth; in
our study, ECC was at 30s. Placental transfusion occurs when cord
clamping is delayed for at least 5s.4
Therefore, in the ECC group of our study, neonates had the
chance to receive the placental transfusion, a major factor
determining neonatal blood volume.
The data from the randomized clinical trials and the controlled
trials over the last two decades do not support the theory that LCC
causes symptomatic polycythemia, even in the studies showing
higher hematocrit levels in late-clamped term and preterm infants.4
Cord blood hematocrit was not affected by placental transfusion.
This agrees with previous studies10,14and shows that cord blood
hematocrit values do not predict polycythemia that results from
We conclude that LCC results in a significant increase in ENBV
at birth with no affecting postnatal hematocrit or the incidence of
neonatal polycythemia. LCC may be beneficial and it does not
appear to harm the healthy neonate. Physicians and midwives may
consider this when deciding whether to perform ECC or LCC.
We did not look at long-term outcomes such as anemia in infancy,
nor did we examine blood viscosity and other hemorheological
parameters. Further trials should evaluate these outcomes as well
as examining the effect of delaying cord clamping for a longer
period of time or changing the position that the neonate is held in
to determine whether these variations result in more clinically
The Research deputy of Mashad University of Medical Sciences financially
supported this study. We thank Dezyani hospital of Gorgan midwives for their
cooperation in the data collection and Mohammad Roshani for revising the paper.
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2 h of life18 h of life
Figure 1 Comparison of asymptomatic polycythemia at 2h of life between study
groups. w2¼0.1; Df¼1; P¼0.733.
Early and late cord clamping
A Jahazi et al
Journal of Perinatology