Umbilical cord clamping and preterm infants
Kinmond et al. (1993) introduced their research on
cord clamping in preterm infants, summarizing some
confused thinking in the early 1990s:
"Despite historical controversy the umbilical
cord is generally clamped immediately,
particularly after preterm delivery [2, 3]. There
is greater awareness of the problems of
excessive placental transfusion
(hyperbilirubinaemia [4], polycythaemia and
hypervolaemia [5]) than of the hazards of
hypovolaemia [6], but claims of reduced preterm
mortality with delayed umbilical cord ligation
have been made for years [7-9]. We report the
clinical effects of a 30 second delay in cord
clamping, holding the preterm infant in a
position facilitating placental transfusion." [1,
p172]
Kinmond et al., by means of sealed envelopes,
assigned women in preterm labor to either a
"regulated" or "random" group. In the regulated
group (n=17) the infant was held below the vaginal
outlet for 30 seconds before clamping the cord. The
random group (n=19) were delivered according to
the discretion of the birth attendant while an
observer recorded the position of the baby and time
of cord clamping - cord clamping was done within 20
seconds for all but one, and only one was held below
the vaginal outlet.
Kinmond et al. terminated the study when use of
sufactant was introduced as an aid to neonatal
respiration. Outcome measures included Apgar
scores, packed cell volume, and peak bilirubin
levels, as well as need for transfusions and/or
supplemental oxygen. Onset of respiration was not
timed, but Kinmond et al. noted that before clamping
the cord 30 seconds after birth many infants in the
regulated group were already crying, which
happened less in the random group, for half of whom
the umbilical cord was clamped within ten seconds
after birth.
No differences in Apgar scores were found, but 13
infants in each group were ventilated. Only one
infant in the regulated group (clamped after 30sec)
required a transfusion as opposed to seven in the
random group (clamped 10 to 20 seconds earlier).
Supplemental oxygen requirement was less for
infants in the regulated group. Peak bilirubin levels
were comparable in each group, but one infant in the
random group had an exchange transfusion. Two
infants in the random group suffered post-
haemorrhagic dilation of brain ventricles One infant
in the random group died unexpectedly at home, but
no deaths occurred in the neonatal nursery.
Higher packed-cell volume and arterial-alveolar
oxygen ratios indicated "less right to left shunting of
deoxygenated blood at cardiac or pulmonary level"
on the first day of life, and both were noted to be
associated with improved final outcome. Kinmond et
al. commented that had synthetic surfactant been
available, 13 of the random group would have
qualified for "rescue" treatment as opposed to only 2
infants in the regulated group [10, 11].
Kinmond et al. cited Peltonen (1981) and
Linderkamp (1982) as having called for reactivation
of research in the early 1980s on positioning and
cord clamping in preterm infants [3, 6]. Kinmond et
al. proposed use of the non-invasive measures of
blood and red cell volumes as means to evaluate the
adaptation and morbidity of premature infants.
Several responses to the paper by Kinmond et al.
were published, which further indicate diverse
opinions held in the early 1990s [12, 14-17].
The first letter does not cite Mahaffey and Rossdale
[13], but clearly reflects what may have been learned
from their paper relating a convulsive syndrome in
newborn foals to clamping of the umbilical cord:
"It is interesting that obstetricians have just
realised what has been known to veterinary
practitioners for many years.' In equine practice
it is mandatory for the stud groom to wait until
the umbilical cord has stopped pulsating before
clamping it; this takes 30-60 seconds. If the cord
breaks-for example, if the mare is standing when
she delivers-then the foal is at risk of infection
as well as anaemia, for as much blood as
possible should be passed to the foal.
Whenever I have conducted a human delivery I
have always insisted that the cord is not
clamped too soon, and I am interested that my
belief has now been scientifically verified." [12,
p398]
It is clear that in 1993, Alexander was allowed to use
her own judgement in not clamping the cord too
soon, and not bound to the current mandate for
immediate clamping of the cord in human births.
In the other responses no reference is made to the
time when ligation of the cord would be done only
after the infant was breathing on his own. However,
Whittel's letter indicates memory of concerns raised
in the 1960's over clamping the cord before
breathing was established:
"The possibility that late clamping of the
umbilical cord may lead to a reduction in
respiratory distress syndrome is not a
particularly new finding, but S Kinmond and
colleagues offer a more scientific approach in
evaluating this phenomenon." [14, p578]
The letter from Evans et al. reveals acceptance with
confidence of human-invented invasive treatments:
"Almost all women in Britain receive oxytocin-
ergometrine (Syntometrine) at delivery, which
causes an increase in plasma oxytocin
concentration within 45 seconds.3 The resulting
contraction could force an excessive volume of
blood into the neonate. If so, the cord should be
clamped before the increase in plasma oxytocin
co.ncentration." [15, p578]
The letter by Wright and Levene reflects an attitude
still current, that more research is needed on the
"simple intervention" of delayed cord clamping
before it can be recommended:
"S Kinmond and others' study of early versus
late umbilical cord clamping shows an apparent
improvement in outcome with a simple
intervention but raises some questions.' Firstly,
is the position of the baby or the timing of the
clamping of the cord the primary factor?
...As the authors state, it is important for
neonatal research to look at simple
interventions such as this. We believe, however,
that further study is needed before firm
recommendations about umbilical cord clamping
can be made." [16, p576]
The letter from Elbourne acknowledges the common
practice of umbilical cord clamping, but "currently
available evidence" does not include all the research
that had been done 40 to more than 100 years
earlier:
"The paper by S Kinmond and colleagues
suggests that modification of a common practice
clamping of the umbilical cord-may have
important implications for the wellbeing of
immature babies.' Most of the previous research
into the timing of cord clamping has
concentrated on babies born near term.
...Inmmature babies are even more likely than
others to have their umbilical cords clamped and
cut immediately after birth to allow resuscitation
and transfer to neonatal intensive care. Kinmond
and colleagues' study suggests that a short
delay may improve outcome without any
obvious deleterious effects. But, on the basis of
currently available evidence, uncertainty
remains. Before widespread changes in practice
are made this finding needs confirmation in a
larger trial with mortality and major respiratory
and cerebral morbidity as the primary
outcomes." [17, p576-7]
(in progress)
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Umbilical cord clamping and
preterm infants: a
randomised trial.
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- Linderkamp 0 (1982)
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- Mahaffey LW, Rossdale PD
(1959) A convulsive
syndrome in newborn foals
resembling pulmonary
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cord clamping in preterm
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- Evans SMJ et al. (1993)
Umbilical cord clamping in
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(1993) Umbilical cord
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- Elbourne D. Umbilical cord
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- Kinmond S et al. (1993)
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- Evans SMJ, Cooper JC, Thorton S. Umbilical cord clamping in preterm
infants [letter]. BMJ 1993 Feb 27; 306(6877):578.
- Wright IMR, Levene MI. Umbilical cord clamping in preterm infants. BMJ
1993 Feb 27; 306(6877):578.
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However, they give little
information about the obstetric features of their
cases, which might be quite important since
matching is essential with such small numbers for
example, were the babies predominantly born
during preterm labour or were they delivered
electively for some obstetric complication? Also
not clear is whether any of the mothers received
steroids to accelerate fetal maturity before delivery.
Although these matters may not be particularly
important as far as the haematological features are
concerned, they certainly are with respect to
ventilation. I believe that more information on
them would be helpful in the interpretation of the
paper."