The fetus does not feel pain.

THE SUGGESTION OF FETAL pain rests on a false equivalence regarding the biology and psychology of the fetus, babies, children and adults. Pain is dependent upon the presence of higher cortical (brain) regions that do not develop before birth and is an experience incompatible with the thinking capacity and emotional development of the fetus. Quite simply, the assertion of pain experience in the fetus presupposes a psychological and biological development that is yet to come.

WHAT IS PAIN?

Most of us think of pain as being similar to a fire alarm. The pain stimulus is the same as hitting the red button, the electric cable to the alarm is the same as a pain fiber and the alarm itself is the brain ringing out pain. This analogy, is quite limited because the button has a quite variable relation with pain experience, there are many cables running to the alarm, and the alarm itself lacks a central focus. It was observed during the 1950s that injury signals are not transmitted to the brain via a single dedicated pathway but by multiple pathways, each with distinctive features including different speeds of transmission and terminations within the brain. Modern neuroimaging techniques, which allow direct observation of brain activity, have demonstrated that pain experience includes many regions of the brain rather than a single identifiable pain centre. Pain involves more than one cable and widespread regions of the brain, rather than one central alarm, including multiple cortical areas (the higher centers of the brain) as well as the lower regions.

Thinking of pain as being like a fire alarm also raises problems with the basic understanding of pain because it suggests that the actual experience rests not with the person but with the event. Pain is defined in terms of a stimulus that is deemed to be painful because it elicits the response of pain. To put that more simply, pain is defined as pain.

To escape this tautological definition, pain is less conventionally understood as not merely the response to physical injury, or disease but as a higher order experience including emotional, cognitive (thinking) and sensory, components. The International Association for the Study of Pain (IASP) has defined pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage" with additional comment that "pain is always subjective." This definition is important because it shifts the focus of understanding away from the stimulus and towards the content of the experience, as well as providing an explanation for why pain experience involves such a lot of brain tissue.

As a higher order psychological experience, pain is dependent upon a highly distributed activation of higher cortical centers. Stimulating one region of the brain, or activating one alarm, is rarely sufficient to produce an experience of pain. This raises the question of whether the fetus has the biological and psychological capacity for pain experience.

FETAL DEVELOPMENT

Fetal skin contains free nerve endings (the alarm buttons) responsible for initial registration of noxious stimulation, from about seven weeks' gestation. These cells mature by 24-28 weeks' gestation and the subsequent fibers penetrate the spinal cord, which also matures around 24-28 weeks.

Projections from the spinal cord (the electric cable) reach the thalamus (the lower alarm) of the brain at about seven weeks' gestation. At seven weeks the thalamus is not yet ready to ring; it is very immature with no indication of the cell structure and organization that will gradually come into focus from around 20 weeks' gestation.

The very first projections from the thalamus towards the cortex (the higher alarm) are apparent from about 12-16 weeks' gestation, but these are projections into the subplate. The subplate is a sort of waiting compartment where fibers accumulate and develop before penetrating the cortical plate developing above. The subplate dissolves during the prolonged growth and maturation of the cortical plate. Similar to waiting in a theater lobby or the parking lot of a ballpark, interactions within the subplate are random and uncoordinated until direction towards a seat is provided.

The thalamic connections do not penetrate the cortical plate, making it to their seats, until 26 weeks' gestation. At this point, the alarm can be considered complete, at least in rudimentary form, but with considerable development of its ringing ability yet to be realized.

From 28 weeks there is massive relocation of subplate fibers into the cortical plate. The cortical plate undergoes tremendous growth increasing in volume by 50% between 29 weeks and term when the characteristic layers, the seat organization, of the cortex becomes apparent.

Obviously development continues after birth, expressed fundamentally by the increasing size of the human brain, but actual neuronal activity in the neonate undergoes important maturation during the first year of life. The neuronal function of the cerebral cortex, especially the somatosensory cortex, the prefrontal cortex and the anterior cingulate cortex, increase by a third from birth to 18 months, and these are brain regions that have been consistently associated with pain experience.

To summarize, fetal development is profound in both speed and extent. Between 12 weeks' gestation and birth quite phenomenal changes occur and while important milestones can be observed the overriding impression is one of continual change--one period of development closes to open another frontier on biological maturation. This is also true for the immediate postnatal period.

FETAL BEHAVIOR

Behavioral responses to touch reflect the changing maturity of the fetal nervous system. At 7.5 weeks' gestation, reflex responses to touch begin. At this point, touching the peri-oral region results in a bending of the head. The palms of the hands become sensitive to stroking at 10.5 weeks and the rest of the body and legs become sensitive at approximately 13.5 weeks. These responses are spinal reflex responses, not dependent on brain activity, and therefore unlikely to contain any conscious component.

Shortly after the development of sensitivity, repeated skin stimulation results in hyperexcitability and a generalized movement of all limbs. This hyperexcitability indicates the immature nature of the fetal nervous system. After 26 weeks this generalized movement gradually gives way to more defined actions that indicate improved organization within the nervous system. Infants delivered at 26-31 weeks, for example, show coordinated facial actions in response to a heel prick that are not present in more premature infants.

Observations of premature infants are often assumed to be relevant for the fetus of similar gestational ages. This is an understandable assumption but one that is likely to be flawed. The environment of the womb consists of warmth, buoyancy and a cushioned environment to prevent tactile stimulation. The placenta provides a chemical environment to encourage sleep and to suppress higher cortical activation in the presence of any intrusive outside stimulation. Inside the womb there is little to be gained from alertness and motion, which can only cause the expenditure of energy with little possibility of escape or other advantage. In contrast to the buffered fetal environment, the intense tactile stimulation of birth triggers behavioral activity and wakefulness and marks the transition from laying down brain tissue to also organizing that tissue with regards to the world now rudely thrust upon it.

THE DIFFICULTY OF BRINGING THE FETUS AND PAIN TOGETHER

Regardless of what development and behaviors occur prior to birth it is simply incorrect to assume that the development is sufficient for pain or that the behavior demonstrates pain. Lloyd-Thomas and Fitzgerald--among the foremost neurological researchers in this area--have commented that "given the definitions of feeling and pain the answer [to the question of whether there is fetal pain] must be no," which reflects the fact that brain development is not just about hooking alarms up to buttons but is about enabling subjective experience. (Lloyd-Thomas AR, Fitzgerald M. "Reflex responses do not necessarily signify pain," British Medical Journal, 1996; 313: 798-799.)

At birth and afterwards there is massive increase in sensory, input and this acts as a form of neuronal crowd control. Repeated sensory input during this critical period of development results in generation and stabilization of functional brain circuits with unused pathways being eliminated. Changes in frontal cortex activity, for example, come at a time when cognitively related behaviors, such as the phenomenon of stranger anxiety and improvements in memory, begin to appear. Similarly the first coordinated motor movements require the further development of specialized motor regions of the brain. Gradual improvements in motor, visual, spatial and sensory, integration mark the disappearance of reflex neonatal behaviors and the emergence of higher conscious function, which will include pain.

It is the development of a representational memory--that is a memory of a certain something that lasts for a certain time--in combination with interactions between the baby and a primary care giver, which makes experience possible. Without an ability to hold something fleetingly in memory there is no means by which a mental representation can be tagged or labeled as a something. Without a primary care giver, the tagging or labeling will not occur. When mommy points to a spot and asks "boo boo?" she is beginning the process of enabling an internal discrimination and with it experience.

It is very. difficult to imagine this undifferentiated existence prior to any symbolic labeling, but it could be like looking at a vast TV screen with all of the world's information upon it from a distance of one inch; a great buzzing mass of meaningless information. Before a symbolic system such as language, an individual will not "know- that something in front of them is large or small, hot or cold, red or green and so on.

These distinctions become possible only insofar as we live in, and relate to, a community of thinking, feeling, talking beings. Language bridges the gap between a prelinguistic, private and unknowable world and the public world of conscious existence, because language is itself a social activity. Language necessarily has to be social because it is the public affirmation of sensory observation (e.g., the sky is blue) and higher-level construction (e.g., liberty). Our inner feelings become experienced, paradoxically, only in so far as they are released into the living world of conscious beings.

So it is for pain, which is also the constituent of particular thoughts and not a reflex response to injury as we have seen. Particular thoughts, however, are composed of particular concepts. "Ouch" is a mindful state that includes the sensation and the associated cognitions and emotion. The experience might feel entirely natural and private, but this is mistaken. The content of our pain becomes meaningful to us only in so far as it is meaningful to others and is the consequence of a developmental process that is social as well as natural. If pain were an entirely private affair, no words would be able to express it because no external flame of reference would be comparable and therefore adequate to express the sensation. Pain is not like this because clearly people do express their painful experiences and these expressions have meaning that allow for diagnosis, treatment and eradication of pain. The expressions of pain are meaningful because they are attached to publicly accessible conditions that warrant their application. If we were trapped inside our own heads, we would be unable to know whether what one person states as pain is the same as someone else's pain. Indeed we would not know if any internal state of our own were the same or different from any other and, as it would not be possible to distinguish any state from any other, no state would consequently exist.

In so far as human beings live in a community of thinking, feeling, talking beings the privacy of experience is broken down and externalized for further analysis. As we are able to externalize our inner world so we are able to reflect upon that world and become self aware or self-conscious. Consciousness is self-consciousness, one cannot reflect upon the world without knowing that it is I who am reflecting. If we were not conscious of being conscious, then we would be unconscious of consciousness, which is an absurdity. It is social development and language that make this conscious awareness possible; symbolic representation does not teach a child to recognize differences that were always there; it teaches them to create differences where none previously existed.

Language does not give voice to experiences already available and fully formed; it creates those subjective experiences by making the quality of those experiences apparent to us, by giving them a structure, by placing them within more abstract categories of thought and by linking them to external reference and social convention. Clearly our access to others' pain is mediated through behavior and language but this is also true of our own pain experience. Social development structures our behavior and language so as to be meaningful to the outside world but with the unnoticed side effect of rendering the child's inner experience meaningful to him or her. While brain development is certainly a necessary precursor of conscious sensory awareness, merely peering inside the head will not reveal the sole source of awareness.

This is how we can be so positive that the fetus does not feel pain. Not only has the biological development not yet occurred but also the post-birth environment so necessary to the development of experience has not yet made itself felt. In short, fetal pain is a moral blunder based on the false equivalence between observer and observed that overlooks the process of development.

A BILL IS NOW BEFORE THE US Congress requiring that doctors "fully inform" women considering abortion after 20 weeks' gestation "regarding the pain experienced by their unborn child." If passed, the Unborn Child Pain Awareness Act (S.2466 introduced in the Senate by Sen. Sam Brownback, Republican of Kansas, and H.R.4420 introduced in the House by Rep. Christopher Smith, Republican of New Jersey) will require doctors to read a statement saying, "Congress finds that there is substantial evidence that the process of being killed in an abortion will cause the unborn child pain, even though you receive a pain-reducing drug." Doctors who do not read the statement could be fined between $100,000 and $250,000 and may lose their license and/or Medicaid funding. The debate has implications for the provision of abortion as some 1.4 percent of abortions in the US take place after 20 weeks. The doctor's statement would include the advice that anesthesia could be administered to the fetus, if the woman wanted.

Conscience asked two leading experts who have reached different conclusions to share their perspectives on whether or not fetal pain exists. Dr. Vivette Glover, director of the Fetal and Neonatal Stress Research Centre at Queen Charlotte's Hospital in London presents the case for the ability of fetuses to feel pain, and Dr. Stuart Derbyshire, assistant professor of anesthesiology at the University of Pittsburgh Medical Center, presents the case against.

Fetal Anesthesia

As the bill proposing that women seeking abortions after 20 weeks gestation should be told about fetal pain and offered anesthesia for their fetus works its way through Congress, it is worth considering what the practicalities are of such a proposal. The only way to examine the use of fetal anesthesia and its impact on the pregnant woman is through experiences gained in fetal surgery, which is still in its early days, with hard data relatively scarce.

There are only four medical institutions that perform major fetal surgical procedures in the US: the Children's Hospital of Philadelphia, the Advanced Fetal Care Center at Children's Hospital in Boston, Vanderbilt University Medical Center in Nashville, Tenn., and the Fetal Treatment Center at the University of California in San Francisco. Generally speaking, surgery on fetuses is only considered when the risk of death or severe disability to the fetus is greater than if there were no intervention, and when the risk to the mother is low.

During fetal procedures the woman is anesthetized using general or regional anesthesia or by sedating her. While there are differing beliefs about this, most seem to agree that the anesthesia given to the woman does not cross the placenta to the fetus in any significant quantities.

Practice varies as regards fetal anesthesia. For example, in Philadelphia they do provide it, while at Vanderbilt they do not. Some centers do not routinely anesthetize the fetus except to keep it immobile during surgery, while others do. In cases where they do anesthetize the fetus, it is administered intramuscularly using fentanyl for analgesia during and after the operation, atropine to reduce the heart rate and vecuronium to ensure the fetus remains still. Current evidence suggests that anesthetizing the fetus does not have a significant impact on the woman, but given the relatively small number of procedures carried out each year, hard data is not yet available.

DR. STUART W.G. DERBYSHIRE is assistant professor of anesthesiology at the University of Pittsburgh Medical Center whose research centers on developing an understanding of how brain function relates to pain experience.