July 2004
10
Factors in need of closer examination: Circulatory
overload, polycythemia, jaundice,
Bilirubin staining of subcortical nuclei damaged by ischemia, Placental fetal-maternal blood barrier,
Cord pulsations are signals to the placenta to continue sending oxygenated blood
Environmental worries
Bilirubin staining of subcortical nuclei damaged by ischemia, Placental fetal-maternal blood barrier,
Cord pulsations are signals to the placenta to continue sending oxygenated blood
Environmental worries
11.
Factors in need of closer examination
a) Circulatory overload,
polycythemia, and jaundice are current reasons for immediate clamping of the umbilical
cord. However, bilirubin-staining is not uniform
throughout the
brain. It has long been recognized that
bilirubin
only enters subcortical nuclei vulnerable to ischemic damage. Ischemia causes impairment of the
blood-brain barrier that prevents normally high neonatal levels of bilirubin from getting into
nerve cells [77- 85]; Zimmerman and Yannet pointed out in 1933, "This differs in no
way from the well known fact that any intravital dye will localize in zones of injury, and will
leave unstained tissues which are not damaged" [79, p757]
b) The placental fetal-maternal
blood barrier should prevent fetal blood from entering the maternal circulation where
antibodies to the Rh-factor can be produced by an Rh-negative mother. Dunn proposed that clamping the umbilical cord
increases blood pressure within the placenta which leads to the leaking of blood [86-87].
c) As long as the umbilical cord
pulsates after
birth, the newborn cardiovascular system is sending a signal to the placenta for continuing oxygenation and/or
blood volume
from the mother. The observation of Desmond et al. made in 1959 that continuing pulsation of the
umbilical stump is associated with respiratory distress remains an important body of evidence
despite having
become part of forgotten history [64].
d) The list of environmental
worries during pregnancy, infancy, and childhood is long and includes not only fears of
bilirubin, but also mercury (in fish, vaccines, and amalgam dental fillings), lead
(in air and household
paint), prenatal exposure to alcohol and other drugs (including anti-convulsant medications like
valproic acid), prenatal exposure to maternal stress hormones, food additives
(coloring and preservatives), carbon monoxide and other fumes from second-hand smoke,
toxic pollutants
like PCBs, prenatal infections like
