Science and Politics of Fetal Pain
By Dr Stuart Derbyshire
The following paper was
written in 1996, in response to the debate about whether
fetuses feel pain. Comments or questions about it can be
sent / e-mailed to the author at the addresses below.
Stuart W. G. Derbyshire,
Ph.D. Asst. Professor
University of Pittsburgh Medical Center,
PET Facility, Room B-938 PUH,
200 Lothrop Street, Pittsburgh,
The Science and Politics
of Fetal pain - Doing the Wrong Thing?
In 1987, the Lancet
published an article unequivocally demonstrating that neonates
receiving fentanyl anaesthesia in preparation for surgery
had improved clinical outcome as compared with neonates
who only received nitrous oxide and curare (1). This research,
and subsequent studies, (2)(3) led to a major reconsideration
of analgesic practice with regard to neonates. In 1992,
theNew England Journalran an editorial calling on
clinicians to 'Do the Right Thing' concluding that 'it is
our responsibility to treat pain in neonates and infants
as effectively as we do in other patients'(4). Since then
it has become common place to assume that neonates feel
pain (5)(6). The assumption that neonates feel pain has
led inevitably to speculation that the fetus may also experience
pain (7). While the discussion about neonatal pain remained
largely confined to the pages of medical texts, the discussion
around fetal pain has attracted the attention of several
major British newspapers and led the British parliament
to discuss the curtailing of abortion (8)(9). Given the
sensitivity of this issue in the United States (10), it
is surely only a matter of time before this issue crosses
the Atlantic. This article evaluates the evidence for and
against fetal and neonatal pain and considers the implications
for current clinical practice, abortion procedure and the
contemporary understanding of pain.
The Evidence that the
Fetus or Neonate can Feel Pain
Anand's seminal work on
the use of fentanyl with neonates undergoing surgery demonstrated
that the major hormonal response to invasive practice could
be significantly reduced with fentanyl added to the anaesthetic
regimen. Specifically it was demonstrated that plasma adrenalin,
noradrenaline, glucagon, aldosterone, corticosterone, 11-deoxycorticosterone
and 11-deoxycortisol levels were significantly greater in
the non-fentanyl group than the fentanyl group up to 24
hours after surgery. The reduction of the 'stress response'
to surgery by fentanyl was considered to be responsible
for the improved clinical outcome of the fentanyl group
who required less post-surgical ventilatory support and
had reduced circulatory or metabolic complications. Anand
and his colleagues later advanced these important and impressive
findings in a report indicating that neonates receiving
deep anaesthesia during surgery had improved post-operative
morbidity compared with those neonates who received lighter
anaesthesia. The reduced hormonal response and improved
clinical outcome following invasive surgery in conjunction
with anaesthetics used for pain relief in adults led naturally
to the conclusion that the neonate could feel pain and that
this pain needed to be controlled.
Dovetailing with the work of Anand and his colleagues was
that of Fitzgerald. Fitzgerald has examined the developing
nervous system of the rat and human fetus with special regard
to the developmental neurobiology of pain (11)(12)(13).
Fitzgerald has reviewed the biological development of the
fetus and examined the possibility of fetal pain at each
stage of development. The impression that a fetus experiences
sensation is apparent at 7.5 weeks gestation when reflex
responses to somatic stimuli begin. At this point touching
the peri-oral region results in a contralateral bending
of the head. The palms of the hands become sensitive to
stroking at 10.5 weeks and the rest of the body and hindlimbs
become sensitive at approximately 13.5 weeks. Shortly after
the development of sensitivity, repeated skin stimulation
results in hyperexcitability and a generalized movement
of all limbs. This hyperexcitability has been interpreted
as evidence for the presence of a functional pain system,
reflecting an immature but intact pain response with early
hypersensitivity to stimulation (14). This is not a view
which is widely accepted, however, and is rejected by Fitzgerald
herself. Prior to 26 weeks the thalamocortical fibres have
not yet penetrated the cortical plate (15), and it seems
unlikely, therefore, that the cortical structures considered
necessary for pain are responding to noxious stimulation.
The evidence for cortical involvement post 26 weeks is enhanced
by behavioral studies which have demonstrated that the response
to noxious stimulation becomes more focused and organized
and can be better discriminated from other distress responses
after 26 weeks (16). As with the hormonal response to surgery,
the behavioral responses can be reduced with the use of
appropriate anaesthetic adding support to the suggestion
that these responses are related to pain perception (17).
Having established that the necessary neurobiology for pain
is in place after 26 weeks and that behavioral responses
to noxious stimulation are present in very premature babies
of approximately 26 weeks gestation, it is logical to suggest
that a fetus of 26 weeks gestation or more will launch a
similar hormonal response to invasive practice as that observed
in the neonate undergoing surgery. In 1994 Giannakoulopoulos
and his colleagues from the Queen Charlottes Hospital in
London, England successfully demonstrated that intrauterine
needling to obtain a blood sample from fetuses of 20-34
weeks gestation resulted in a hormonal stress response analogous
to that seen by Anand et al seven years previously (18).
They demonstrated that needling the innervated intra-abdominal
portion of the umbilical vein rather than the placental
cord, which is not innervated, resulted in increased cortisol
and -endorphin concentrations in fetal plasma. If this
group can now demonstrate that the hormonal and neural 'stress
response' can be prevented with the use of appropriate anesthetics
then they will have mirrored the criteria which have led
to the widespread acceptance of 'neonatal pain'.
The Evidence Against
The undisputed discovery
that the neonate and fetus launch a hormonal and neural
response to invasive practice can not be considered definitive
proof that there is anexperienceof pain. Anexperienceimplies
that sensations have been interpreted in a conscious manner.
Even when combined with the observations of behavior and
improved clinical outcome when using anesthetics, there
is still no proof that there is anexperienceof pain.
Although all of these phenomena are associated with the
notion of 'pain', none of them adequately describe or explain
the phenomenological experience of 'pain'. These phenomena
may exist independently of conscious experience. The relationship
between the physiological responses of nociceptors, the
hormonal and other responses of the CNS and the behavioral
outcome of these changes to the psychological response has
yet to be determined (19).
Unless it can be reasonably suggested that the fetus has
a conscious appreciation of pain post 26 weeks gestation,
then the responses to noxious stimulation post 26 weeks
are still essentially just behaviorally complexreflexresponses,
similar to the responses prior to 26 weeks. Despite the
importance of providing evidence for the conscious appreciation
of pain, the fetal and neonatal literature largely tries
to ignore this issue. Anand, for example, highlighted the
clinical findings with neonates as being of greater importance
than 'any philosophical view on consciousness and 'pain
perception''. Giannakoulopoulos et al distanced themselves
from any implied fetal pain experience with the statement
'a hormonal response cannot be equated with the perception
of pain'. In a report for the British Department of Health
(Foetal pain: an update of current scientific knowledge.
A paper for the Department of Health May 1995) Fitzgerald
even went so far as to say that 'true pain experience [develops]
postnatally along with memory, anxiety and other cognitive
brain functions' leaving confusion as to what the 'untrue'
pain experience of a fetus may be. More recently Lloyd-Thomas
and Fitzgerald have suggested that if feeling and pain are
properly understood then the fetus cannot be said to feel
Such equivocation is perhaps not surprising in view of the
general failure of material interpretations, i.e. interpretations
which focus specifically upon the biological properties
of human beings (21), to deliver a coherent account of human
consciousness (22). Nevertheless, if a proper assessment
of neonatal and fetal pain is to be undertaken, then we
should examine the structure of the psychological experience
'pain', as the biological structures have been examined,
and then work backwards to the fetus and neonate to decide
whether it is likely or possible that these psychological
structures are in place.
As Fitzgerald has identified, pain experience is now widely
seen as a consequence of an amalgam of cognition, sensation
and affective processes, this amalgam is commonly described
under the rubric of the 'biopsychosocial' model of pain
(23). Pain is no longer regarded as merely a physical sensation
of noxious stimulus and disease, but is seen as a conscious
experience which may be modulated by mental, emotional and
sensory mechanisms and includes both sensory and emotional
components. The whole biopsychosocial concept emphasizes
the multidimensional nature of illness, injury and pain
rather than emphasizing pain as purely a physical fact of
illness or injury. Pain has been described as a multidimensional
phenomena for some time (24) and this understanding is reflected
in the current IASP (International Association for the Study
of Pain) definition of pain as 'an unpleasant sensory and
emotional experience associated with actual or potential
tissue damage, or described in terms of such damage' (25).
If this 'multidimensionality' is the basis of conscious
pain experience, it seems unlikely that we can attribute
this experience to the neonate or unborn fetus, which is
naive as to all the cognitive, affective and evaluative
experiences necessary for pain awareness. This is accepted
in the current definition of pain that is further extended
to state: 'pain is always subjective. Each individual learns
the application of the word through experiences related
to injury in early life.' Pain does not, so to speak, spring
forth 'from the depths of the person's mind' prior to any
experience, but is gradually formed as a consequence of
general conscious development.
A further reason to doubt the viability of fetal pain post
26 weeks gestation is the development of the fetal cortex.
Although it is true that the thalamocortical fibres penetrate
the cortical plate at approximately 26 weeks gestation,
the cortical regions which have been identified as important
in processing the suffering components of pain (26)(27)
do not become fully responsive until after birth (28). These
structures, especially the anterior cingulate cortex (29),
have a plasticity which allows for learning and adaptation
and therefore retain the capacity to have a more dynamic
relationship with conscious awareness. Interestingly, this
capacity is not shared by the structures associated with
sensory detection, such as the somatosensory cortex, which
develop earlier but are less likely to have an involvement
in the processes associated with pain experience. The concept
of pain as a product of learning and adaptation is pursued
in more detail underImplications for Pain Research.
The Implications for
Current Clinical Practice
The debate about fetal pain
need not affect clinical practice involving the fetus or
neonate. Evidence that the stress response, which the fetus
and new-born launches in response to physical insult, has
known detrimental consequences is acceptable even to those
who do not accept that pain is experienced. New borns who
have been operated on without analgesia show increased mortality
compared with new-borns who receive analgesia. There is
also evidence that early physically stressing experiences
may produce detrimental changes in later responses to potentially
painful experience, such as inoculation (30). Therefore,
in the cases of invasive practice where there is a clear
clinical rational for the use of anesthetics, which does
not rely upon the additional diagnosis of pain, the withholding
of analgesia for fetus' and neonates should remain an unethical
practice. As exciting advances in fetal surgery are being
made continuously, it is imperative that similar clinically
orientated research be carried out with the fetus.
Where the clinical advantage of anaesthetic is less clear,
however, it is probably wise to avoid potentially dangerous
procedures for the fetus or neonate, and probable uncomfortable
procedures for the mother. There are those who argue that,
while there is no consensus on this issue, clinicians should
act according to the precautionary principle of assuming
that pain is experienced until it is conclusively proved
otherwise. However, as few clinical procedures are entirely
risk free it seems more appropriate to reserve any form
of intervention for occasions when it is known to be necessary.
A consideration of vaginal childbirth helps to place the
discussion about fetal pain into some context. Childbirth
is known to give rise to the hormonal and neural stress
response which has been used as evidence for fetal and neonatal
pain, this has led at least one popular British newspaper
to run an article questioning whether babies feel pain during
childbirth (31). It seems unlikely, however, that a process
which the very vast majority of people have passed through
is having long term detrimental consequences, and there
is evidence which suggests the contrary to be the case (32)(33).
It is still unknown exactly what the consequences of a hormonal
stress response may be both for adults (34) and newborns.
Under these circumstances an increase in relatively problematic
anaesthetic, or even surgical practices such as caesarean
section, to avoid fetal/neonatal 'pain' seems unnecessary
and irrational (35)(36).
The Implications for
Fetal pain is obviously
an important issue for those carrying out fetal operations
and other invasive practices, but it is also of interest
for those involved in abortion procedure and for those motivated
to restrict the current abortion legislation. The broadly
accepted conclusion that recorded responses to noxious stimulation
prior to 26 weeks gestation arereflexresponses, not
dependent on conscious appreciation, is important as it
eliminates much of the generated concern regarding abortion.
In 1994 just 94 abortions, out of more than 160,000 carried
out in the UK, were later than 24 weeks (37). If it is accepted
that consciousness is essential to the pain experience,
and that consciousness is contingent upon psychological
development, it would follow that even after 24 weeks gestation
it would be more appropriate to describe fetal reaction
to stimuli as reflex responses than as pain.
Guidelines on the termination of pregnancy for fetal abnormality
issued by the UK Royal College of Obstetricians and Gynaecologists
(RCOG) draws on the work of Fitzgerald (1995) which suggests
strongly that the immaturity of the fetal nervous system
prevents conscious awareness of pain before 26 weeks gestation.
The document argues that 'it follows that up to this gestation
the method of abortion should be selected to minimise the
physical and emotional trauma to the woman' (38).
Regardless of one's own views on whether late term induced
abortions may cause pain to the fetus, the issue warrants
special attention because almost all late terminations are
of wanted pregnancies where the putative parents may be
emotionally vulnerable. Often, during counselling, they
express concern about what the fetus may 'feel' during an
abortion. In these circumstances it is common for the putative
parents to think of the fetus as a 'baby' and to attribute
to it the qualities that they anticipated their child would
have were it to be born. In such cases good sympathetic
clinical practice would require steps to be taken to reduce
the concerns of the woman.
In the UK, the RCOG recommends that measures to stop the
fetal heart should be taken in all terminations after 21
weeks gestation. This is to ensure that there is no possibility
of the abortion resulting in a live birth. After 26 weeks
the guidelines suggest that it is not possible to know the
extent to which the fetus is aware and so after this gestation
it is suggested that 'methods used during abortion to stop
the fetal heart should be swift and involve a minimum of
injury to fetal tissue.' Even if the fetus is not aware,
as we suggest, these guidelines would be appropriate to
avoid unnecessary distress to the woman.
The paramount interests of the woman in abortion procedures
is an important principle. Arguments that with viability
the fetus becomes a patient and the doctors' responsibilities
towards the woman need to be balanced against those of the
fetal patient remain controversial (39)(40). The view that
the pregnant woman is the patient while the fetus is cared
for on behalf of the woman endures among many clinicians
and is in my view the ethical stance (41)(42).
Concern about fetal suffering is raised by those who oppose
abortion in principle as a reason to restrict some methods
of abortion. In both the US and the UK legislative changes
have been proposed which would outlaw a late abortion procedure
known by gynaecologists as intact dilation and evacuation
and by opponents of abortion as 'partial-birth abortion'.
In both countries the method was defended by the medical
establishment on the grounds that there may be circumstances
when such practice was in the interests of the woman. It
was for this reason that President Clinton exercised his
right of presidential veto in respect of the Partial Birth
Abortion Ban Bill of 1995 (H.R. 1833/S 939) which had been
approved by Congress. Clinton correctly stated that: 'By
refusing to permit women in reliance on their doctors' best
medical judgement, to use this procedure when their lives
are threatened or when their health is put in serious jeopardy,
Congress has fashioned a Bill that is neither consistent
with the Constitution nor with sound public policy' (43).
The Implications for
The implications of accepting
the notion of neonatal and fetal pain for pain research
are profound. The consequence of such a view is to undermine
the current theoretical outlook of most pain researchers,
namely the 'biopsychosocial' model of pain, the undermining
of the current definition of pain (44)(45), and the return
of ideas more closely resembling the discredited ideas of
In the absence of any conceptual framework to account for
a fetal/neonatal experience of pain, the fetal literature
is drawn inexorably towards the discredited ideas of 'specificity'
and 'pain centers'. Within the discussion of fetal pain,
pain fibres (or peptides or neurotransmitters) are proposed
to be stimulated and relay information to suggested pain
centers somewhere in the brain. As for specificity, a painful
stimulus therefore becomes that which activates the pain
center, and pain becomes activity in the pain center. Specificity
theory, however, has long been rejected because the definition
of pain based on a direct relationship between stimulus
and response has failed to resolve many of the major issues
in pain research. Interpretations of injury based on a direct
relationship between stimulus and pain cannot account for
the variable link between stimulus and pain experience.
This variable link is well documented (47)(48)(49)(50),
and is a consequence of the fact that pain experience is
a multidimensional phenomena contingent upon processes involved
in general conscious awareness, namely evaluative, emotional
and cognitive processing. The biopsychosocial model of pain
has also encouraged a less 'specificity biased' view of
central pain neurology which has long been dogged by specificity
theorists searching for pain centers (51). Classical neurology
has viewed the central projection to the somatosensory cortex
as essentially a pain center, a region necessary and sufficient
for the experience of pain (52). The information about noxious
stimuli that travels via the spinothalamic tract to excite
the lateral group of thalamic nuclei interconnected with
somatosensory cortex, undergoes few alterations between
the spinal cord and cortex (53). Excitatory responses in
monkey somatosensory cortex are generally restricted to
both innocuous and noxious mechanical and thermal stimuli.
Somatosensory neurons have receptive fields that are small
or at least confined to one limb and always contralateral
(54). Such a system is ideal for providing detailed information
about the location and characteristics of particular noxious
stimuli but is not well suited for processes associated
with affective and cognitive responses to noxious stimuli.
The conscious appreciation of pain cannot be explained within
this system, instead a 'neuromatrix' (55) of regions, incorporating
anterior cingulate, prefrontal and insula cortices which
show a plasticity with learning and development, is proposed
as necessary for the experience of pain. Functional imaging
studies have now demonstrated that a number of cortical
regions are activated in response to pain which conform
to the concept of a neuromatrix (56)(57).
While the neuromatrix is an important step away from specificity,
a step which is threatened by the concept of neonatal and
fetal pain, so long as the neuromatrix is seen as sufficient
for pain experience it will fall foul of the same problems
that the materialist accounts of consciousness face and
can ultimately be reconciled with neonatal and fetal pain.
The only way to avoid the failings of materialism, avoiding
the view that the higher mental functions are fixed a priori
or that consciousness is a product of metaphysical forces
(58), is to see consciousness, and within it the experience
of pain, as a consequence of developmental processes which
the fetus and newborn baby are yet to pass through. According
to one developmental model of pain, stimulus information
is eventually organized and elaborated in the central nervous
system with respect to three hierarchical mechanisms (59).
The first two mechanisms in the hierarchy are perceptual-motor
processing followed by schematic processing. Both these
mechanisms are considered preconscious. Perceptual-motor
processing involves the activation of an innate set of expressive
motor reactions to environmental stimuli. Schematic processing
involves the automatic encoding in memory of the experience
to produce a categorical structure representing the general
informational and sensory aspects of pain experiences. A
set of conscious abstract rules about emotional episodes
and associated voluntary responses is proposed to arise
over time as a consequence of self observation and conscious
efforts to cope with aversive situations. While rather mechanistic
and far from ideal, this model outlines how the pressure
of interacting with others gradually forces the subordination
of our instinctual, unconscious, biology to our developing
The response of fetuses and neonates to invasive practice
is a valuable research area that should lead to better clinical
practice in the future. Basing this research upon the assumption
that there is pain experience, however, could lead to the
hasty introduction of unnecessary and possibly detrimental
anaesthetic procedures as well as increasing the distress
faced by those women who seek abortion. In addition, the
focus on fetal pain is likely to result in a considerable
challenge on the current understanding of pain - a challenge
which will push back the past 30 years of pain research
and undermine the contemporary conceptual framework for
understanding pain. Such changes do not appear to be advantageous
and may even be damaging to the pain field in general and
to the treatment and understanding of nociceptive responses
in the fetus and newborn baby.
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