From when does a human fetus feel pain?

April 6, 2024

One of the most frequent and controversial questions that have been generated in the area of sexual and reproductive health, along with the discussions on the legislation and management of abortion, is the following: Does a human fetus feel pain? In part these discussions have followed the idea that the beginnings of the development of the central nervous system are sufficient condition to have the experience of pain.

Considering that there is no consensus in addressing this issue, in this article we present some of the research and theories that have been made to discuss the issue.

Related article: "The 3 phases of intrauterine or prenatal development: from the zygote to the fetus"

Can a human fetus feel pain?

In the year 2006 Stuart Derbyshire, member of the department of psychology of the National University of Singapore and expert in cognitive science, discusses this subject taking as axis a governmental policy of the United States. The latter determined that it was the doctor's obligation notify women who intend to have an abortion about the existence of some indications that abortion can cause pain to the fetus.

From this, the doctor also had the obligation to offer the woman the option of reducing said pain by applying drugs before aborting. The consequence of not warning about all of the above could cost doctors thousands of dollars.

On the other side of the world, in England, were offered at the beginning of the last decade a series of images that sought to argue in favor of the idea that the fetus has a series of cognitive and emotional experiences. Said images finally impact on British policies on pre-abortion pharmacological interventions to mitigate the pain of the fetus.

Stuart Derbyshire discusses the available evidence on all of the above by analyzing the neurobiological development of the fetal period along with the experiential dimension of pain.

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When does fetal development begin?

Fetal development is that which occurs from week 12 . That is to say that the embryo that has evolved after the first 3 months of gestation is considered as "fetus".

In the course of the next 5 or 6 months until delivery occurs, the fetus is expected to develop cells, organs, tissues and even systems that will be a necessary condition to ensure its birth. Having said that, we will define what pain is from a psychological perspective, as well as those elements that are considered necessary to be able to experience it.

What is the pain?

The International Association for Pain Studies (IASP) says that pain is an unpleasant sensation and an emotional experience associated with a potential or actual damage of a tissue , or, it is an experience described in terms of said damage.

From this we can say that pain is a conscious experience, and not just the response to noxious stimuli (Derbyshire, 2006). With which is also a subjective experience that can be modified qualitatively between one person and another. In addition, for an organism to experience pain they need a series of physiologically mature structures . A complex network of cortical regions must be activated; what can happen even in the absence of a real noxious stimulation.

In case the noxious stimulation is present, the latter is an external event that generates electrical activity between the brain and the nerves of the skin, which finally generates a painful experience. That is, for an organism to feel pain, there must first be the possibility that the nervous system is activated .

Likewise, for the experience of pain to occur other cognitive processes related to the state of consciousness and memory must be developed, which in turn mean and discriminate an event as "painful" (an issue in which the way in which it is fundamental is essential). the one we learn to name this event through the others).

In other words, although pain is an individual experience (of physiological processes and cognitive processes with which we generate a mental representation of pain), it can also be seen as an experience experienced in interaction with others.

Experience of pain and fetal development

Approximately, it is in the 7th week of gestation when the nerve terminals begin to develop, as well as some parts of the spinal cord (which is a fundamental connector of the brain and which will lead to the thalamus, an important organ for sensory experiences).

This lays the foundation for creating a hypothalamic structure that is a necessary condition for the experience of pain.But the latter does not mean that the hypothalamic activity is consolidated: the density of the neuronal cells that line the brain is in the process of consolidation. Before such consolidation ends, the neuronal cells are not able to process harmful information from the periphery.

In other words, the nervous system is not fully developed and mature, so that we can hardly sustain or conclude that the pain experience occurs during fetal development.

The first evidence of sufficient hypothalamic activity begins to appear between week 12 and 16 of gestation . It is then that the neural connections within the cerebral cortex begin to mature. Afferent fibers develop from weeks number 23 to 25. However, there is not enough functional neuronal activity to talk about experience of pain in the fetus, because the spinothalamic fibers have not been connected to the cerebral cortex. .

Week number 26 and other fundamental stages

The thalamic projections in the plaque of the cerebral cortex are the minimum anatomical condition necessary to experience pain, and they are completed by the 23rd week of gestation. At the same time, peripheral nerve terminals develop that will generate reflexes in the cerebral cortex.

For this reason, several investigations have suggested that the minimum gestational week to suspect the experience of pain in the fetus is number 26 (around 7 months of gestation), which is when the electrical activity is similar to that presented by children and adults when they respond to harmful situations , or, when they explain an experience as painful.

On the other hand, the secretion of different hormones is also needed; process that begins to be observable in fetuses from the first 18 weeks of gestation.

The problem, Derbyshire (2006) tells us, is that what happens inside the placenta is significantly different from what happens outside of this , both in neurochemical terms and in the way to respond to noxious stimuli, and therefore on sensitive experiences.

In this same sense, the most classic studies about pain experiences have been to relate the electrical activity of the brain to the experience of pain that is verbally reported by the same person.

Because this can not be done with a fetus, scientific research has focused on Theorize about the possibility that there is pain experience through analyzing the embryonic development of the nervous system . From there they suggest that the experience of pain exists because it is similar to what a child or an adult already verbalizes.

That is, the investigations have had to resort to the interpretation of secondary evidence, and for the same reason they have only been able to talk about indications, not conclusive results about the experience of pain in fetal development.

In summary

To feel pain not only we need the ability to discriminate between different sensory stimuli . Nor is it about reacting to potentially harmful stimuli (a quality known as "nociception"). The experience of pain also involves responding in a conscious way, that is, we also need the ability to discriminate between different experiences; issue that is generated by the interactions with our caregivers after birth, among other processes such as the development of the mind.

We need, therefore, a mature nervous system that allows us to process and represent this stimulus as harmful and later as painful.

There are numerous important neurobiological processes that begin in week 7, week 18 and week 26 of pregnancy . These same have been considered by many as the stages where a human fetus might feel pain. What Derbyshire (2006) warns us quickly is that the subjective experience that accompanies pain can not be deduced directly from anatomical development, since these developments are not those that give rise to the conscious contents of pain.