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Does a Fetus Feel Pain at 20 Weeks?

A number of Republican House members say scientific research proves a 20-week-old fetus can feel pain. This is a complicated and controversial topic in science, but the ability to feel pain at that specific point in gestation is unproven.

The House Republicans made their remarks during a debate on the Pain-Capable Unborn Child Protection Act, which would ban abortions beyond 20 weeks, with some exceptions for victims of rape or incest and if the mother’s life is in danger. It passed the House on May 13 by a margin of 242-184.

Several lawmakers made similar statements on the House floor:

Rep. Ralph Abraham, May 13: As a doctor, I know and I can attest that this bill is backed by scientific research showing that babies can indeed feel pain at 20 weeks, if not before.

Rep. Dan Benishek, May 13: The Pain-Capable Unborn Child Protection Act will prevent abortions from occurring after the point at which many scientific studies have demonstrated that children in the womb can actually feel pain.

Rep. Charles Boustany, May 13: The scientific evidence is clear: unborn babies feel pain. They feel pain at 20 weeks post-fertilization.

These statements, and others like them, are problematic because of their definitive nature. Scientific research on pain in the fetus is extremely complicated, primarily because pain is a subjective experience and a fetus cannot indicate if something hurts.

Research on the topic has centered around the stages of brain and nervous system development, and what is known regarding the processing of pain in the brain. We reviewed the literature and spoke with several experts, and we conclude that a firm starting point for pain in the developing fetus is essentially impossible to pin down, and that definitive claims regarding pain perception at 20 weeks are unfounded. We take no position on the bill itself.

Subjectivity and Evidence Reviews

Published research generally supports an experience of pain being possible only later in gestation than 20 weeks. A synthesis of available evidence was published in the Journal of the American Medical Association in 2005 by experts from the University of California, San Francisco, and elsewhere, and their report concluded: “Evidence regarding the capacity for fetal pain is limited but indicates that fetal perception of pain is unlikely before the third trimester.” The third trimester begins at 27 to 28 weeks from conception.

The perception of pain requires an awareness of an unpleasant stimulus — receptors throughout the body must send a signal to the brain, where it can be processed as pain. One reason the JAMA review finds early pain perception unlikely is that the connections between the thalamus, a sort of relay center in the brain, and the cortex have not yet formed. This happens between 23 and 30 weeks gestational age, and the authors argue these connections are a precursor for pain perception. They also cite studies using electroencephalography that have shown the capacity for functional pain in preterm newborns “probably does not exist before 29 or 30 weeks.”

A March 2010 report from the Royal College of Obstetricians and Gynaecologists in the United Kingdom concluded similarly:

RCOG, 2010: In reviewing the neuroanatomical and physiological evidence in the fetus, it was apparent that connections from the periphery to the cortex are not intact before 24 weeks of gestation and, as most neuroscientists believe that the cortex is necessary for pain perception, it can be concluded that the fetus cannot experience pain in any sense prior to this gestation.

The American Congress of Obstetricians and Gynecologists has agreed with RCOG’s and the JAMA study’s findings, writing in 2012 that “[s]upporters of fetal pain legislation only present studies which support the claim of fetal pain prior to the third trimester. When weighed together with other available information, including the JAMA and RCOG studies, supporters’ conclusion does not stand.”

SciCHECKinsertWe asked several members of Congress for evidence to support the claims regarding fetal pain at 20 weeks. Abraham’s office declined, citing the congressman’s personal experience as a family practice physician. Cole Avery, Abraham’s spokesman, told us in an email that the congressman has “read countless medical journals and articles during that career that have led him to the conclusion that babies feel pain at 20 weeks. There’s no single article or fact sheet that led him to this conclusion; he reached it during an entire career of study.”

Others did send materials in support of the claim. Boustany’s spokesman sent us several fact sheets and references that contained numerous citations on neuroanatomy, development and related topics; one of these is available at this site, which endorses the idea that pain is experienced at 20 weeks after fertilization.

For example, Boustany’s documentation claimed a 2007 paper in the journal Behavioral and Brain Sciences “demonstrated evidence that children born missing virtually all of the cerebral cortex nonetheless experience pain.” That paper, by Swedish neuroscientist Bjorn Merker, was a review of available evidence regarding “consciousness without a cerebral cortex.” It did conclude that “consciousness,” which would include the perception of pain, may reside not only in the cortex but in other, earlier developing brain regions as well.

In 2013, Merker told the New York Times that his work had only “marginal bearing” on fetal pain. In fact, his paper, he said, “did not deal with pain specifically.”

The material from Boustany’s office also cited a number of papers detailing that the sensory receptors on the skin begin to appear as early as seven to eight weeks, and that these are linked by nerve cells to the brain’s thalamus and subcortical plate by 20 weeks. This suggests that pain signals can be received by a fetus and sent to the brain, where they are processed — but only if processing does not actually require a fully developed cerebral cortex. Some experts have indeed argued that some degree of pain perception may not require a cortex, but again, there is no way to confirm this in a fetus.

A common argument, and one also mentioned in Boustany’s materials, has to do with a fetus’ response to stimuli. A heel prick from a needle used for amniocentesis, for example, can result in the fetus recoiling, much as an adult would to a painful pinprick.

Studies have shown, however, that the recoil is more of a reflex controlled by the “lower brain” (which is involved with more base functions like breathing than with consciousness) or the spinal cord and does not necessarily reflect an experience of pain. In fact, the same response can be seen in anencephalic infants, who are born missing large parts of the brain. As the JAMA review explains: “[F]lexion withdrawal from tactile stimuli is a noncortical spinal reflex exhibited by infants with anencephaly and by individuals in a persistent vegetative state who lack cortical function.”

Put another way, the experience of pain is different from what is known as nociception. Nociception refers to the body’s ability to perceive harm — this can be achieved below the level of consciousness, as with reflexes. A paper published in 2001 in the journal Bioethics explains the difference: “[W]hile nociception is neural activity, pain is an unpleasant feeling. It follows that while pain requires some level of consciousness, nociception does not.”

Pain Intensity and Fetal Viability

Proponents of 20-week abortion bans often also cite Kanwaljeet Anand, a professor of pediatrics, anesthesiology and neurobiology at the University of Tennessee Health Science Center. He has stated that pain may indeed occur in a fetus, through other neurobiological mechanisms than in an adult, as early as 20 weeks post-fertilization or even before. A claim attributed to him that the pain perceived is “possibly more intense than that perceived by term newborns” is repeated often, including during the House floor debate by Rep. Kristi Noem, a Republican from South Dakota:

Noem, May 13: This is the stage where we know the baby can feel pain, and could be viable outside the womb with proper care. In fact, there is evidence that the pain that the unborn baby feels is even more intense than what a young child or an adult would feel because their nervous system isn’t developed enough to block that pain.

In testimony before Congress in 2005, however, Anand was specifically asked about this idea. He responded: “No. There is — that is not my opinion. And I really don’t have any data to suggest that that could be true, or the other way.” He explained that there is some data suggesting a lower pain threshold in preterm newborns than in full-term newborns or older children, but extrapolating that back to the gestation period is not possible.

Anand also told the New York Times in 2013 that he has turned down many requests to testify in court cases regarding fetal pain, objecting to the politicization of his research.

Noem also mentioned that a fetus at 20 weeks “could be viable outside the womb with proper care.” Rep. Virginia Foxx, a Republican from North Carolina, also mentioned this and cited a recent study on extremely preterm infants:

Foxx, May 13: The New York Times reporting just last week on a study that the New England Journal of Medicine published that found that 25 percent of children born prematurely at the stage of pregnancy covered by this legislation survive.

The study in question analyzed the outcomes regarding 4,987 babies born before 27 weeks gestational age.

(It is important to note that gestational age and post-fertilization age are different. Gestational age, which the study on viability used, is measured from the mother’s last normal menstruation before conception. Post-fertilization age is the time since conception. Generally, one can add two weeks to post-fertilization age to calculate an approximate gestational age. H.R. 36 refers to abortions after 20 weeks post-fertilization age, which is equivalent to 22 weeks gestational age.)

We asked Foxx’s office for clarification, but received no response. We are unsure to what exactly her 25 percent figure refers.

In the study she referenced, a total of 357 babies were born at 22 weeks gestational age, and 5.1 percent of them survived; 2.0 percent survived without moderate or severe impairment. At 23 weeks, the rate rose substantially, with 23.6 percent surviving overall and 11.3 percent surviving without impairment. By 26 weeks, most babies survive, at 81.4 percent, and 58.5 percent survive without impairment.

Noem is right that a fetus at 20 weeks post-fertilization — or 22 weeks gestational age — “could be viable outside the womb with proper care.” But at least in one study, only 2 percent of these babies survived without moderate or severe impairment, and only 5.1 percent survived at all.

Some experts argue, as Anand does, that pain in the fetus is not precisely the same as in an adult and may occur earlier than 20 weeks. Martin Platt, an honorary and clinical reader in neonatal and pediatric medicine at Newcastle University in the U.K. who has criticized arguments against early fetal pain, told us in an email that “it is now clearly recognized that infants and preterm babies process pain through different structures than adults, so ‘adult based’ arguments are not relevant.” Still, he said, “we are no closer to defining a gestational age below which” pain might not be felt.

In his 2011 editorial in the journal Archives of Diseases in Childhood, Platt stressed the need for better understanding of this complicated issue before firm proclamations are made:

Platt, 2011: [T]he literature on fetal behaviour, perception, organisation, movement and responses focuses largely on fetuses above 28 weeks of gestation, with a relative lack of studies on the fetus between 20 and 24 weeks. This results in too much reliance on neuroscience, too much reference to animal work, too much extrapolation from both of these and too little real-world human investigation on which to base a realistic view. No one would deny that there are important issues to be confronted, but a sensible debate needs a solid base of rigorous empirical enquiry.

Editor’s Note: SciCheck is made possible by a grant from the Stanton Foundation.

– Dave Levitan