Foetal Sentience

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A report by the All Party Parliamentary Pro-Life Group

Reproduced with permission from Catholic Medical Quarterly, XLV11 no 2, November 1996, p6

"A fisherman once told me that fish have neither sense nor sensation but how he knewthis, he could not tell me." Bertrand Russell HUMAN KNOWLEDGE-Its Scope and Limitations


R P Balfour FRCOG, Consultant Gynaecologist, Princess of Wales Hospital, Bridgend Professor John Bonnar MD, FRCOG, Professor of Obstetrics and Gynaecology, Trinity Centre For Health Services, Dublin

Dr Peter Doherty, General Practitioner Dr Terence Dow ling, Child Psychiatrist Dr Michael Jarmulowicz, Consultant Pathologist, Royal Free Hospital, London

Professor David Jenkins FRCOG,Professor of Oh-ste trics and Gynaecology, Cork University Dr Peter MeCullagh, John Curtin School of Medi-cal Research, Australian National University Dr John McLean, Anatomist

Professor John Marshall, Emeritus Professor of Clinical Neurology, University of London W M 0 Moore, Consultant Obstetrician, BUPA-Legal Services, Manchester; Director, Central Man-chester Child Growth Project

Professor David Short, Emeritus ProfessorofClini-cal Medicine, Ijniversity of Aberdeen Pamela Sims FRCOG, Consultant Obstetrician and Gynaecologist, Newcastle General llospital Professor Ronald Taylor, ERCOG, Emeritus Pro-fessor of Obstetrics and Gynaecology, St Thomas I loSpital. I~on don

Professor John Utting, Emeritus Professor of An-aesthesia, University of I iverpool.

Dr Margaret White, General Practitioner.


There is no direct, objective method of assessing pain or suffering in another subject, human or non--human, prenatal or postnatal.

Indirect methods of assessing pain include:

a) questioning the subject, assuming the subject to possess both the capacity to remember and to communicate,

b) observing the type of stimulus and the subject's response to it,

c) confirming the presence and integrity of the anatomical structures subserving the apprecia-tion of pain.

Any stimulus capable of being interpreted as painful must activate sensory receptors and initiate the transmission of this activation to that part of the brain where the appreciation of pain occurs. Coincidentally the painful stimulus may also activate a spinal reflex mechanism which results in withdrawal from the painful stimulus by reflex muscle action.

Since no direct objective method of assessing fetal pain exists, the crucial question with regard to fetal sentience is:

At what stage of human prenatal development are those anatomical structures subserving the appre-ciation of pain present and functional?

The balance of evidence at the present time indicates that these structures are present and functional before the tenth week of intrauterine life.


At present, no known method exists whereby we can directly assess or observe pain in another subject (human or non-human) with absolute certainty. Our knowledge of pain is subjective. For example, if we see an animal kicked, we are confident in assuming it will feel pain because we know that if we were kicked we would feel pain.

In addition, we can deduce or infer that a subject is suffering or has suffered pain from a number of lines of indirect evidence.

1) Interrogation of Subject

The most informative method rests on interrogation of the subject. To achieve this, the subject must possess the capacity to feel pain, as well as the capacity to communicate. If the pain is to be described at a later time, the subject must also be able to remember.

Lack of either of the two latter capacities precludes the subject from reporting pain.

Animals and fetal, neonatal and some mentally impaired humans lack the capacity to communicate and/or the capacity to remember. As a New England Journal of Medicine editorial stated:

"...of course infants are notable to complain later about their case".1

Some paralysed patients are unable to vocalise their complaints of pain.

People with Alzheimer's Disease certainly experience pain and may be able to describe it at the time, but lack capacity to remember and to give an account of it later.

Thus we see that to claim, as have Members of Parliament,2 that "awareness of pain" depends upon 'ability to remember", is scientifically untenable.

2) Physical Reactions to Stimuli and the Central Nervous System

i) When it is impossible to interrogate a subject about experience of pain, other types of information must be relied upon. The most obvious additional information is response to the suspected painful stimulus: the commonest

form of response is movement. In addition. recent research into hormonal responses (carried out at Queen Charlotte's Hospital in London) has shown changes in fetal plasma following intrauterine needling similar to those found in mature humans experiencing pain.3

ii) A second source of information that may help to gauge the likelihood of pain is the nature and intensity of the presumed painful stimulus. Would one expect such a stimulus to cause pain? (This is the subjective assessment.)

iii)A third, less evident, requirement in assessing the likelihood that a subject is experiencing pain, is knowledge about the structure of the nervous system in that class of subject. Is the degree of development of the nervous system consistent with the requirement for pain awareness ? (The latter is as yet little understood.) None of these types of information is likely to provide irrefutable evidence that the subject is feeling pain.

Consequently the practice in veterinary and human medicine is to presume that the subject may be able to feel pain from any given procedure, unless this can be excluded with reasonable confidence.


It is, of course, necessary for both veterinarians and doctors to bear in mind that our scientific knowledge regarding the identity ofthose nervoussystem structures responsible for pain awareness is incomplete and changing as research progresses (see below). In recent times our knowledge about the minimal structure necessary for pain awareness by the nervous-system increasingly suggests that lower levels of complexity are required: for a subject to feel pain, development need not be as advanced as was previously thought.

Consequently, there have been changes in good medical practice in different areas such as:

i) At one time surgery was carried out on new-born and premature infants with minimal anaesthesia. Since 1986 this has been considered unacceptable as it is recognised that neonatal subjects can experience severe pain.

ii) In 1991 the Scientific Advisers to the Bundesarztekammer (Federal Medical Council) in Germany advised that sedation, analgesia or anaesthetics should be used during operations carried out on the unborn infant.

iii)Another example is the increasing tendency of animal experimentation codes of practice to require administration of analgesics to animals that are being used in experiments. In Australia this includes the fetus of any given species.4


The debate about fetal sentience focuses principally on the question of the fetus's capacity to experience pain. It is therefore necessary briefly to review what can be reliably said about the neurophysiological requirements for the existence and exercise of this capacity.

Nerve Structures Involved In Pain Awareness

1) The anatomical structures involved in pain awareness consist of:

i) sensory receptors capable of responding to a painful stimulus;

ii) nerves to conduct the impulses generated in these receptors to the spinal cord;

iii) nerve fibres within the spinal cord which transmit these pain impulses to the brain;

2) Two factors related to the transmission of impulses following the application of a noxious and/or potentially painful stimulus must also be explained:

i) the relevance of reflex responses in assessing pain awareness;

ii) the identity of brain structures for pain awareness.

A reflex response, in its simplest form, is a movement following a stimulus: it is an automatic reaction such as a child withdrawing her hand from a hot object.

The reflex response to a painful stimulus uses those nerves responsible for the transmission of the impulse to the spinal cord (lii). In addition, the nerves which emerge from the spinal cord to activate the muscles involved in the reflex movements must also be present. Thus a reflex action requires that all of these nerves be intact and functional.

It is important, however, to recognise that such a reflex movement does not necessarily require the transmission of an impulse to the brain structure responsible for pain awareness (1iii). The reflex response of movement and pain awareness may both follow a single noxious/painful stimulus but they are quite separate events.

One can see this distinction in common everyday experiences. For instance, if one puts a hand into very hot water, it will be withdrawn immediately, to be followed within a split second by severe pain.

The significant difference between the reflex withdrawal and the awareness of pain is that while the reflex movement can be reliably observed by another individual, pain awareness can only be experienced by the subject and may only be deduced by the observer.

Reflex Movement Without Pain

In specific situations, either the reflex movement or the pain can occur on its own in response to a noxious stimulus. The reflex movement may occur

- without being followed by pain - if the nervous-system pathways which transmit impulses to the brain centres responsible for pain awareness have been blocked by surgery or drugs. The same thing would apply in the case of a subject who had broken his neck: the reflex reaction would occur, but he would not be able to feel pain.

çÈ_ _This might also occur in the fetus if the nerves which bring about the reflex action have developed before those of the pain pathways.

It is on this basis that some MPs have claimed that the fetus cannot feel pain.2

However, such a claim can only be scientifically sustained if we can confidently exclude beyond reasonable doubt that the stimulus which brought about the reflex movement does not also reach any centre in the brain concerned with pain awareness. To claim that a fetal movement in response to noxious stimulus is not accompanied by pain is warranted only if this exclusion can be firmly established.

The argument that "it's only a reflex" would carry little weight if advanced in the context of animal experimentation For example, the claim that "withdrawal of the dog's leg when immersed in boiling water was only a reflex and not to be taken as an indication that the dog experienced pain" would not be acceptable.

Development Of The Cerebral Cortex And The Thalamus

Inexplicably, in the discussion of fetal pain awareness, the possibility that a fetus may feel pain and yet show no reflex response seems to have been overlooked. Yet, when one considers fetal development, this may well occur.

The fetus will not manifest reflex movements until the nerve fibres which emerge from the spinal cord have formed the necessary connections with those muscles which bring about movement.

Only if we assume that the development of the nerves responsible for muscle movement occurs before that of the sensory nerves which ascend to the brain centres responsible for pain awareness can we conclude that there will be a period when there will be reflex action without the fetus actually being aware of pain. However, there is considerable evidence to the contrary suggesting that it is more likely for the fetus to experience pain before it has the capacity to move.

The anatomical structures involved in awareness of pain in the mature animal or human have not been completely identified. The programme of development of these structures in fetal animals or humans is even less completely understood.

Nevertheless, current information suggests that many functions which were originally assumed to be exclusively located in the cerebral cortex can be undertaken by lower centres in the brain. Those who claim that "sentience is a function of the cerebral cortex"2 seem to overlook this scientific evidence.

i) Anencephaly

Much ofthe information relating to the role of lower centres of the brain (eg the thalamus) has come from clinical experience of infants suffering from anencephaly (an abnormality in which the cerebral cortex fails to develop) and a related condition. hydranencephaly. The latter is compatible with prolonged survival whereas anencephaly is not.

Commenting upon the common assumption that anencephalic infants "have to be" incapable of feeling pain because of the lack of development of the cerebral cortex, a group of clinicians from the University ofCalifornia, Los Angeles Medical Centre (UCLA) stated: ". . . it neither logically, nor physiologically follows that anencephalic infants by definition can neither feel nor experience pain"5 (see also footnote A, below). Ihe UCLA group made the further point that to ignore actual pain

Footnote A

The paper a/so states: "In experimental animals, brain stem structures have been shown to mediate complex behaviours, sometimes traditionally assumed to be cortical, including binocular depth perception, habituation, learning and discriminative conditioning. Similarly, decerebrate(anencephalic and hydranencephalic) human newborns with relatively intact brain stems can minfest a surprising repertory of complex behaviours, including distinguishing their mothers from others, consolability, conditioning and associative learning although irritability and decreased ability to habituate are also common.".

reaction of anencephalic infants on the basis that a cerebral cortex was required amounted to begging the question of where pain was experienced.

ii) Hydrocephaly

Equally dramatic suggestions that many functions hitherto attributed to the cerebral cortex can be effectively accomplished by centres lower in the brain have emerged from research by Professor John Lorber of Sheffield University.6

Lorber has used scanning techniques to study a number of individuals with hydrocephalus who in other respects appear and behave normally. He has demonstrated that reduction of the thickness of the cerebral hemisphere (normally about 45 millimetres) to a "millimetre or so" had occurred in one otherwise normal university student.

Thus Lorber concluded that "the cortex is probably responsible for a great deal less than most people imagine" and he inferred that many assumed cortical functions in this person were located in primitive deep brain structures unaffected by hydrocephalus6 (see footnote B, below).

There are indications that awareness of unpleasant sensations may occur in one of these deeper structures, the thalamus.

iii) PYS and Damage to the Thalamus

Damage to the upper parts of the brain does not generate pain (the brain can be operated on after local anaesthesia of the scalp and overlying skin),

Footnote B

In the central nervous system cerebro-spinal fluid (CSF) flows freely through a system of interconnecting spaces called ventricles within the brain. The largest of these spaces, the lateral ventricles, are situated one within each of the cerebral hemispheres. In hydrocephalus the free flow of cerebral spinal fluid (CSF) is blocked, usually during fetal life or early infancy, and it accumulates within and dilates the lateral ventricles. As a result, the overlying brain tissue including the cortex is significantly reduced in thickness.

but the "thalamic syndrome" which occasionally follows damage to the blood supply to the thalamus is characterised by intractable, burning pain.

Another important observation emerged from the findings at the post mortem examination of the American PVS victim, Karen Quinlan, who lived for over 10 years in a comatose state. This examination established that there was comparatively slight damage to the cerebral cortex (in which some MPs have been led to believe consciousness resides)2 whereas the thalamus had suffered very substantial damage. These findings suggest that the thalamus plays a more crucial role in consciousness and awareness than was previously thought.7

Anatomical observations of the human fetus have indicated that some parts of the thalamus have developed by 9 weeks gestation and that the nerves responsible for carrying sensation from the skin to the spinal cord develop by 6-7 weeks.

Apart from the inferences concerning fetal capacity for pain that can be drawn from these anatomical studies, a number of direct observations of the response of the human fetus to stimulation ex utero (removed from the womb) have been reported. A report from Fitzgerald and Windle 8, who made some of the most striking observations, stressed that many other reports were based on assessments of fetuses which were adversely affected by maternal anaesthesia and oxygen deficiency. They attribute the failure of those reports to observe fetal movements after stimulation to the effects of narcosis and lack of oxygen (anoxia) after placental separation (separation from the mother).

They reported that sensory and motor nerves were functioning in the eighth week of gestation as indicated by muscular contraction in response to stimulation.8 There can be little doubt. on anatomical grounds, that some sensory nerves mature at 6-7 weeks and, therefore, do so before their motor nerves which cause muscle movement. Hence, observations of very early fetal reactions to stimuli are limited hy the slower development of motor nerves.

Thus when MPs equate the movements of a human fetus at this stage of development (possessing as it does a nervous system that is already quite extensive) with the reactions of a single cell amoeba2 in which any equivalent nervous system is totally lacking, they parody science in the best tradition of W.S. Gilbert's derivation of Poo Bah's ancestry from an amoeba.


1) As indicated previously, the question of whether a subject, who lacks the capacity to communicate, is feeling pain can only be deduced. Essentially then, any decision about the likelihood that any subject (animal or human) feels pain requires society to decide what is an acceptable risk of error.

How confident must we be that our actions will not infiict pain on a sentient creature? In this type of situation, it is generally required that the burden of proof (of non-sentience) rests on the person who is undertaking the action.

That this is recognised in analogous situations may be seen in the various codes of practice under which experimentation on animals may be conducted.

For what is reflected in those codes is the recognition not of a remote but of a very strong possibility that fetal animals can experience pain.

For instance, the code of the Australian National Health and Medical Research Council explicitly requires that "unless there is specific evidence to the contrary, investigators must assume fetuses have the same requirements for anaesthesia and analgesia as adult animals of the species"'.

We can also see a similar concern to avoid the possibility of causing pain, in guidelines on human experimentation. For example, in testimony before a Committee of the European Parliament enquiring into time limits on human embryo experimentation, a French researcher explained:

"Other proposals have been based on the ability of the embryo to experience pain. but at the present state of scientific knowledge, the exact point in time when this occurs is not known.

Day 17, when the first signs of the formation of the nervous system are visible, has been proposed by The Royal College of Obstetricians Gynaecologists."9

This is reflected in the Warnock Committee Report (paras 11.20-11.21) which states:

".. .the strictly utilitarian view . . . suggests that the ethics of experiments on embryos must be determined by the balance of benefit over harm or pleasure over pain. Therefore, as long as the embryo is incapable of feeling pain, it is argued that its treatment does not weigh in the balance. According to this argument the time limit for in vitro development, and for research on the embryo could be set either when the first beginnings of the central nervous system can be identified or when functional activity first occurs . . . The Royal College of Obstetricians Gynaecologists suggested that embryos should not be allowed to develop in vitro beyond a limit of seventeen days, as this is the point at which early neural development begins."

Therefore, considerations about the capacity of the fetus to experience pain should be based on the best scientific information currently available. At the very least, these should match the standards in relation to burden of proof that apply to experimental use of animals.

Such a view was recently expressed succinctly by Professor Christopher Hull (Vice President of the Royal College of Anaesthetists and Professor of Anaesthesia at the University of Newcastle) during a BBC World At One news item on the dilation and-extraction abortion technique (in which fetuses from about 13 weeks gestation are dismembered). He commented:

"So far as I am concerned I would be prepared to accept that the fetus does not feel pain when somebody proves to me that they don't feel pain. But. until that time I would have to assume that they do."11

Indeed, the burden of proof, surely, should rest upon those who accept the principles of the British Abortion Act, to show that the fetus does not feel pain rather than to demand conclusive proof that s/he does, which is at present the case. In a more general context, the point can be made that many in the community would recognise that the obligation not to harm other human subjects extends considerably beyond that of not causing pain.12

I) Rogers MC. Do the right thing. Pain relief in infants and children. New England Journal of Medicine (1992) 326 page 55.

2) Amendment to Early Day Motion 636 House of Commons Notices of Motions 1.3.95. (See Appendix 1).

3) Giannkopoulos X. et al (1994 Fetal plasma corisol and Bendorphin response to intrauterine needling. Lancet 344: 77-81.

4) Australian National Health and Medical Research Council "Code of Practice for the care and use of animals for scientific purposes".

5) Shewman D. A. Captron A M. Peacock W J. Schulman B 1. 1989 The Use of Anencephalic Infants as Organ Sources. Journal of The Americana Medical Association 261 1773-1781.

6) Lewin R. Is your brain really necessary? Science (1980) 210 page 1232.

7) Kinney H C. Korein J, Panigraphy A et al Neuropathological Findings in the Brain of Karen Quinlan. New En gland J Med. 1994:330: 1469-75.

8) Fitzgerald J E Windle W F "Some Observations On Early Human Fetal Movements". Journal of Comparative Neurology. (1942). 76, p159-167.

9) Anonymous. Responses to nine questions concerning rescarch on human embryos. Human Reproduction (1986) 1 page 265.

10) Report of the Committee of Inquiry into Human Fertilisation and Embryology (1984) par 11.20 and 11.21.

11) BBC World At One, 29.4.1996.

12) Professor Maria Fitzgerald. l~tal Pain: an update of current scientific knowledge. A Paper for the Department of Health. May 1995.

Mrs Ann Winterton, M.P. Chairman of The All Party Parliamentary Pro-Life Group wishes to thank Dr Peter McCullagh who prepared the original paper and Dr John Mclean who collated additional material. She also wishes to thank Mrs Phyllis Bowman, National Director of The Society for the Protection of Unborn Children who was responsible for the final collation and editing.