Comments on the Cochrane Review of early vs "delayed" cord clamping

The Cochrane Review  "Early versus delayed umbilical cord clamping in preterm infants" was published in January 2006; it had been online since July 2004, and referenced by Dr. Alistair Philip in his response to the letters Dr. Morley and I sent in response to the "WAIT A MINUTE" article by Philip and Saigal.

Dr. Morley's feedback

Dr. Morley submitted feedback to the Cochrane Review article, which was published with the article in January 2006.  He questioned whether it was ethical for any of the studies subsequent to the one by Kinmond et al. (1993) to have been carried out.  He pointed out the lack of truly informed consent obtained from parents for assignment to the immediately-clamped "control group," and that the only meaningful control group would be one in which no clamping of the cord would be done.

It seems clear to me from my beginning to read research reports from decades  ago, even over a hundred years ago, that the evidence of harm done by  clamping of the cord has been available since long before Apgar devised her  scoring system.

Children and their families versus "rigorous research protocols"

As for many current-day research reports, this one concludes with a remark that more research is needed.  The tragic error is that the research has been done, and long lost track of in the dustbin of forgotten history.  As a matter of safety, the research of the past should be reviewed thoroughly before any more experimentation with newborn infants is allowed.

Animal rights activists would object to suffocation of newborn monkeys anymore, as was done by Windle (1969) and Myers (1972), but it would be better to experiment further with monkeys, and observe their developmental course than to engage in long-term observations of children subjected to varying intervals of umbilical cord clamping.

Research with monkeys led to the conclusion that the brainstem damage incurred was "minimal," but it involved an important midbrain center in the auditory pathway for analysis of the kind of complex acoustic information needed for learning to speak.  Behavioral testing of monkeys was minimal, but showed up life-long deficits in manual dexterity and memory.

Some incredible introductory remarks

The Cochrane Review opens with several mind-boggling comments.  In the   first paragraph of the article, following the statement that optimal timing for   when to clamp the cord is unclear, the authors state:

"Attempts to transfuse the baby from the placenta, by leaving the cord unclamped for longer at the time of birth, may conflict with a perceived need for immediate resuscitation, which usually takes place away from the mother."

Then in the second paragraph they go on to say:

"Cord clamping is part of the third stage of labour, which is the time between delivery of the infant and the placenta."

They then state that delayed clamping results in less need for transfusions and respiratory support, which they say must be weighed against delay in resuscitation, hypothermia,  and development of polycythemia and hyperbilirubinemia.

Flawed thinking?

It seems to me the very premise of this review is flawed.  Most serious is the idea that "leaving the cord unclamped" may conflict with a perceived need for immediate resuscitation, and that resuscitation usually takes place away from the mother - actually several questionable presumptions were put forth.  First, leaving the cord unclamped indicates that clamping the cord is viewed as the natural thing to do, or perhaps unquestionably a natural human intervention.  Second, that leaving the cord unclamped may conflict with the possible need for immediate resuscitation.  Third, that resuscitation can and usually does take place away from the mother.

Further, the statement that cord clamping is part of the third stage of labour is ridiculous.  Clamping the cord is an intervention that interferes with the normal course of the birth of the placenta.  Clamping the cord abruptly stops placental circulation from and to the infant.  Research preceding by decades any of the studies considered for inclusion in the Cochrane Review showed that blood volume ebbs and flows between infant and placenta depending mainly upon contractions of the uterus - of course interventions like epidural anesthesia may abolish contractility of the uterus.

Breaching the fetal-maternal placental barrier

Clamping the cord leaves blood under unnatural pressure behind in the placenta.  This may be the most likely reason for bursting of blood vessels on both the fetal and maternal sides of the placenta, and provide the source of fetal blood to which the mother may develop antibodies, especially to the Rh factor if her blood type is Rh negative.  The placental barrier is an achievement of evolution that predates the human race, and prevents maternal rejection of the fetus, which may present many incompatibilities arising from paternal-maternal genetic differences.

Finally in the 1940s discovery that leakage of Rh-positive blood into the Rh-negative mother's circulation during birth of her first child was the reason for her production of antibodies to the Rh factor.  Erythroblastosis fetalis had been discussed in the medical literature at least since 1875.   That its occurrence may in many cases be due to umbilical cord clamping should be considered.  We know that even in 1773 Charles White was critical of the by-then common practice of tying the cord, often immediately, after the birth of a child.

Long neglected data omitted from the Cochrane Review

Among the studies omitted from the Cochrane Review, the oldest was from the year 1963, and rejected because of "inadequate randomization."  In fact the authors of this paper, Taylor et al (1963) commented on the reason for this inadequate randomization in a particularly outrageous statement:

"It became necessary to include private patients in the premature group to increase enrollment; the planned randomization of these infants as to time of cord clamping failed." p894.

Consent was apparently more difficult to get from private patients to be randomly assigned to one group or another.  Only clinic patients, those without means to pay for private care - and, childbirth was not covered by medical insurance in 1963.  Perhaps liability was considered less for clinic patients, whose delivery was by the resident who happened to be on duty at the time, and whose actions would be more easily defended in any legal action by the hospital where he was in training.

Even the research on time of cord clamping in the 1930s, 40s, and 50s relied upon patients of lower economic status - somewhat reminiscent of the 1940s research in which one group of negro men with syphilis were not treated, in order to make scientific studies of the outcome.

The most ethical studies of umbilical cord clamping were made by Haselhorst in Germany, who measured placental transfusion using a clamp that could be unclamped (Haselhorst 1929).  These older studies merit inclusion in a review of umbilical cord clamping.  The constraints of opaque envelope and other means of randomization considered important for "good experimental design" are of questionable value, in light of all the existing but neglected data already in the literature.

Physiological control cases - waiting for pulsations to stop

I do agree with Dr. Morley, that the only truly worthwhile controls for research on umbilical cord clamping, at any time, should be the cases in which physiological closure of the cord occurs naturally, the cases in which the cord is not cut until pulsations in it have ceased.  This should be feasible now that many women are requesting this in their birthing plans.

In their response to Morley's feedback, Rabe et al. stated:

"Also, in all seven studies babies in the control group had early or immediate cord clamping. This reflects clinical practice in many parts of the world, where for many years the norm has been to clamp the cord as soon as possible after delivery. It is absolutely appropriate to use normal clinical practice as the control intervention."

This being the case, there should be no ethical conflict in doing research with monkeys - one group with immediate cord clamping, and allowing pulsations in the cord to cease in the control group.  Then investigate the long-term developmental outcomes in these two groups of animals.  The only difference in the group with immediate cord clamping and the earlier studies by Windle (1969) and Myers (1972) would be not artificially preventing the newborn from beginning to breathe on its own.

In progress - 3/23/06

From:

http://placentalrespiration.net/ sprepu

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