Is fetal pain a real evidence?

An Evidence-Based Discussion of Fetal Pain and Stress

BACKGROUND

The concept of fetal pain results from procedures conducted without anesthesia in preterm newborns and fetuses, which indicate that it is possible to examine fetal pain based on stress hormone, metabolic, and behavioral changes. Anatomical and physiological data suggest that fetuses become capable of processing nociceptive stimuli around midgestation, although the associated changes in fetal brain development remain unclear. What constitutes fetal pain remains controversial in the light of the definition of pain adopted by the International Association for the Study of Pain (IASP), which posits pain as an "unpleasant sensory and emotional experience."

SUMMARY

Here, we examine the notion that human fetuses cannot "experience" pain and potential implications of this claim. We highlight the key scientific evidence related to fetal pain, including clinical studies on pain in fetuses and preterm newborns. We argue that consistent patterns of stress hormones, metabolic changes, body movements, hemodynamic changes, and pain-related facial expressions in fetuses exposed to invasive procedures overcome the need for subjective proof of pain as articulated in the IASP definition. No study to date has conclusively proven the absence of fetal pain beyond the age of viability.

KEY MESSAGES

Based on the current evidence, we propose that all fetuses receive anesthesia regardless of the invasive procedures being performed to guarantee the least possible pain and physiological, behavioral, or hormonal responses without exposing the mother or her baby to unnecessary complications.

Difficulties in Adaptation of the Mother and Newborn via Cesarean Section versus Natural Birth-A Narrative Review

Birth is a physiological act that is part of the morpho-functional economy of the maternal body. Each stage in the act of birth has a predetermined pathway that is neurohormonally induced and morpho-functionally established through specific and characteristic adaptations. Like maternity, childbirth also has an important impact on the maternal body as a biological structure and psycho-emotional behavior. Cesarean section performed at the request of the mother with no medical underlying conditions besides the prolonged hospitalization risk can also cause breathing problems in children, delayed breastfeeding, and possible complications in a future pregnancy. Vaginal birth remains the path of choice for a physiological evolution pregnancy. Although erroneously considered safe and easy today, cesarean section delivery must remain an emergency procedure or a procedure recommended for pregnancies where birth is a risk to the mother and to the child, as cesarean section itself is a risk factor for negative outcomes for both mother and baby. This review summarizes the impact that both cesarean section and natural birth have on mother and newborn in their attempt to adapt to postpartum events and extrauterine life.

An integrative perspective on the role of touch in the development of intersubjectivity

Touch concerns a fundamental component of sociality. In this review, we examine the hypothesis that somatomotor development constitutes a crucial psychophysiological element in the ontogeny of intersubjectivity. An interdisciplinary perspective is provided on how the communication channel of touch contributes to the sense of self and extends to the social self. During gestation, the transformation of random movements into organized sequences of actions with sensory consequences parallels the development of the brain's functional architecture. Brain subsystems shaped by the coordinated activity of somatomotor circuits to support these first body-environment interactions are the first brain functional arrangements to develop. We propose that tactile self-referring behaviour during gestation constitutes a prototypic mode of interpersonal exchange that supports the subsequent development of intersubjective exchange. The reviewed research suggests that touch constitutes a pivotal bodily experience that in early stages builds and later filters self-other interactions. This view is corroborated by the fact that aberrant social-affective touch experiences appear fundamentally associated with attachment anomalies, interpersonal trauma, and personality disorders. Given the centrality of touch for the development of intersubjectivity and for psychopathological conditions in the social domain, dedicated research is urged to elucidate the role of touch in the evolution of subjective self-other coding.

Counting gross fetal movement using a fetal movement acceleration measurement recorder in two fetuses with gastroschisis

We used the fetal movement acceleration measurement recorder to count gross fetal movement in two fetuses with gastroschisis. In conclusion, both fetuses moved as much as normal fetuses, which suggested that normal fetal movement could indicate reassuring status also in fetuses with malformation when they have normal neurological developments.

Pregnancy in Slaughtered Lambs and Sheep—A Cross-Sectional Study in Three Abattoirs in Switzerland

Simple Summary

The slaughtering of pregnant livestock and its relevance to animal welfare has become an ethically controversial topic. In this study, the prevalence of sheep and lambs being slaughtered while pregnant in Switzerland was assessed as well as the stage of pregnancy and the life signs of the fetuses. Data collection was carried out over one year in three Swiss abattoirs. Overall, 7.6% of the female animals were pregnant at slaughter, and 25.5% of them were in the third trimester of pregnancy, where 81.1% of the fetuses showed signs of life, such as a heartbeat or umbilical artery pulsation. To assess the relevance of animal welfare, it is discussed whether fetuses feel pain and stress. Even though science disagrees as to whether fetuses are capable of feeling conscious pain, it cannot certainly be ruled out, which is why the slaughter of pregnant sheep and lambs should be minimized as much as possible.

Abstract

The slaughter of pregnant sheep and goats is not restricted in Switzerland. The aim of this study was to assess the prevalence of pregnant sheep and lambs being slaughtered in Switzerland and to determine the state of gestation and vital signs of the fetuses in order to assess the need to take measures and raise awareness of this issue. The data collection was carried out from March 2021 to February 2022, comprising 115 days in three abattoirs. A total of 18,702 sheep and lambs were included in this cross-sectional study, and 8770 were female (46.9%), 663 of which were pregnant at slaughter (7.6%). The pregnancy rate varied by age category: 404 lambs (6.1%) and 259 sheep (11.9%) were pregnant. The highest pregnancy rate was found in winter (25.7%). Among the 663 pregnancies, more than a quarter were multiple pregnancies (28.2%). A total of 169 animals were in the third trimester of pregnancy (25.5%), where living fetuses were mainly found (81.1%). As it cannot be definitively ruled out that fetuses feel conscious pain, the data from this study underline that, from an ethical point of view, there is a need for action and that measures must be taken to reduce the number of pregnant slaughtered animals.

Society for Maternal-Fetal Medicine Consult Series #59: The use of analgesia and anesthesia for maternal-fetal procedures

Pain is a complex phenomenon that involves more than a simple physical response to external stimuli. In maternal-fetal surgical procedures, fetal analgesia is used primarily to blunt fetal autonomic responses and minimize fetal movement. The purpose of this Consult is to review the literature on what is known about the potential for fetal awareness of pain and to discuss the indications for and the risk-benefit calculus involved in the use of fetal anesthesia and analgesia. The recommendations by the Society for Maternal-Fetal Medicine are as follows: (1) we suggest that fetal paralytic agents be considered in the setting of intrauterine transfusion, if needed, for the purpose of decreasing fetal movement (GRADE 2C); (2) although the fetus is unable to experience pain at the gestational age when procedures are typically performed, we suggest that opioid analgesia should be administered to the fetus during invasive fetal surgical procedures to attenuate acute autonomic responses that may be deleterious, avoid long-term consequences of nociception and physiological stress on the fetus, and decrease fetal movement to enable the safe execution of procedures (GRADE 2C); and (3) due to maternal risk and a lack of evidence supporting benefit to the fetus, we recommend against the administration of fetal analgesia at the time of pregnancy termination (GRADE 1C).

Neurodevelopmental outcomes of preterm infants who have experienced procedural pain in the neonatal intensive care unit: a systematic review protocol

OBJECTIVE

This systematic review will assess the association between painful procedures performed on preterm infants while hospitalized in the neonatal intensive care unit and short-, mid-, and long-term neurodevelopmental outcomes.

INTRODUCTION

Preterm infants hospitalized in the neonatal unit undergo many painful procedures. The repetition of these painful procedures in a preterm infant with an immature nervous system can have consequences for their neurodevelopment.

INCLUSION CRITERIA

Prospective and retrospective observational study designs will be included in this review. Studies of preterm infants (less than 37 weeks of gestation) hospitalized in the neonatal intensive care unit who have undergone painful procedures, with or without skin breaking, will be considered for inclusion in this review. Our main variable will be neurodevelopment, measured in the short, medium, and long term.

METHODS

A comprehensive database search will be undertaken in CINAHL, PubMed, MEDLINE, Embase, and Cochrane Central Register of Controlled Trials. We will limit the search to articles published in English or French. Study selection, data extraction, and critical appraisal will be conducted by two independent reviewers. If possible, meta-analysis will be performed; otherwise the results will be presented by descriptive synthesis.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42020189762.

Society for Maternal-Fetal Medicine Consult Series #59: The use of analgesia and anesthesia for maternal-fetal procedures

Pain is a complex phenomenon that involves more than a simple physical response to external stimuli. In maternal-fetal surgical procedures, fetal analgesia is used primarily to blunt fetal autonomic responses and minimize fetal movement. The purpose of this Consult is to review the literature on what is known about the potential for fetal awareness of pain and to discuss the indications for and the risk-benefit calculus involved in the use of fetal anesthesia and analgesia. The recommendations by the Society for Maternal-Fetal Medicine are as follows: (1) we suggest that fetal paralytic agents be considered in the setting of intrauterine transfusion, if needed, for the purpose of decreasing fetal movement (GRADE 2C); (2) although the fetus is unable to experience pain at the gestational age when procedures are typically performed, we suggest that opioid analgesia should be administered to the fetus during invasive fetal surgical procedures to attenuate acute autonomic responses that may be deleterious, avoid long-term consequences of nociception and physiological stress on the fetus, and decrease fetal movement to enable the safe execution of procedures (GRADE 2C); and (3) due to maternal risk and a lack of evidence supporting benefit to the fetus, we recommend against the administration of fetal analgesia at the time of pregnancy termination (GRADE 1C).

Slaughter of Pregnant Cattle at an Austrian Abattoir: Prevalence and Gestational Age

Simple Summary

Cattle constitute a major part of the livestock in Austria. Dairy cows are sent to slaughter at the end of their production cycle, whereas heifers are admitted to slaughter either after a fattening period or because of reproductive disorders. In several countries, evidence has been presented that pregnant female cattle are admitted to slaughter, with implications for animal welfare and meat quality. Until today, no data are available on the frequency of pregnant cattle slaughtered in Austria. Over a one-year period, we examined 1633 female cattle in one abattoir, and pregnancy was detected in 104 animals (6.4%). Sixteen cattle were in the last third of gestation. Percentages of pregnant cattle sent to slaughter were higher in beef and dual-purpose breeds than in dairy cattle, but this was not statistically significant. Measures to minimize the number of pregnant cattle sent to slaughter should be implemented at farm-level.

Abstract

The slaughter of pregnant cattle raises ethical–moral questions with regard to animal welfare, but also concerns of consumers because of higher levels of sex steroids in the meat from pregnant cattle. Since no data on the slaughter of pregnant cattle in Austria were available, we examined uteri of slaughtered female cattle in one Austrian mid-size abattoir. Sample size was calculated for an assumed prevalence of 2.5% (±1%; 95% confidence interval) of cows or heifers slaughtered in the last trimester of pregnancy and amounted to 870 cows and 744 heifers. 1633 female cattle of domestic origin were examined, most of them of dual-purpose type. Pregnancy was detected in 30/759 heifers and in 74/874 cows (an overall prevalence of 6.4%). The number of cattle in the last trimester of pregnancy was 16 to 26, depending on the evaluation scheme. We found no significant differences in percentages of pregnant cattle sent to slaughter for beef, dual-purpose and dairy breeds, although the latter group demonstrated the lowest percentage. Our results are comparable with those from previously conducted studies in other member states of the European Union. Measures to avoid sending pregnant cattle to slaughter should be implemented at farm-level.

Analgesia for fetal pain during prenatal surgery: 10 years of progress

Some doubts on the necessity and safety of providing analgesia to the fetus during prenatal surgery were raised 10 years ago. They were related to four matters: fetal sleep due to neuroinhibitors in fetal blood, the immaturity of the cerebral cortex, safety, and the need for fetal direct analgesia. These objections now seem obsolete. This review shows that neuroinhibitors give fetuses at most some transient sedation, but not a complete analgesia, that the cerebral cortex is not indispensable to feel pain, when subcortical structures for pain perception are present, and that maternal anesthesia seems not sufficient to anesthetize the fetus. Current drugs used for maternal analgesia pass through the placenta only partially so that they cannot guarantee a sufficient analgesia to the fetus. Extraction indices, that is, how much each analgesic drug crosses the placenta, are provided here. We here report safety guidelines for fetal direct analgesia. In conclusion, the human fetus can feel pain when it undergoes surgical interventions and direct analgesia must be provided to it. IMPACT: Fetal pain is evident in the second half of pregnancy. Progress in the physiology of fetal pain, which is reviewed in this report, supports the notion that the fetus reacts to painful interventions during fetal surgery. Evidence here reported shows that it is an error to believe that the fetus is in a continuous and unchanging state of sedation and analgesia. Data are given that disclose that drugs used for maternal analgesia cross the placenta only partially, so that they cannot guarantee a sufficient analgesia to the fetus. Safety guidelines are given for fetal direct analgesia.

Development of Brain Networks In Utero: Relevance for Common Neural Disorders

Magnetic resonance imaging, histological, and gene analysis approaches in living and nonliving human fetuses and in prematurely born neonates have provided insight into the staged processes of prenatal brain development. Increased understanding of micro- and macroscale brain network development before birth has spurred interest in understanding the relevance of prenatal brain development to common neurological diseases. Questions abound as to the sensitivity of the intrauterine brain to environmental programming, to windows of plasticity, and to the prenatal origin of disorders of childhood that involve disruptions in large-scale network connectivity. Much of the available literature on human prenatal neural development comes from cross-sectional or case studies that are not able to resolve the longitudinal consequences of individual variation in brain development before birth. This review will 1) detail specific methodologies for studying the human prenatal brain, 2) summarize large-scale human prenatal neural network development, integrating findings from across a variety of experimental approaches, 3) explore the plasticity of the early developing brain as well as potential sex differences in prenatal susceptibility, and 4) evaluate opportunities to link specific prenatal brain developmental processes to the forms of aberrant neural connectivity that underlie common neurological disorders of childhood.

New insights into fetal pain

Fetal pain is difficult to assess, because the main feature needed to spot pain, is the subject's capability of declaring it. Nonetheless, much can be affirmed about this issue. In this review we first report the epochs of the development of human nociceptive pathways; then we review since when they are functioning. We also review the latest data about the new topic of analgesia and prenatal surgery and about the scarce effect on fetal pain sentience of the natural sedatives fetuses produce. It appears that pain is a neuroadaptive phenomenon that emerges in the middle of pregnancy, at about 20-22 weeks of gestation, and becomes more and more evident for bystanders and significant for the fetus, throughout the rest of the pregnancy.

Slaughter of Pregnant Cattle in Denmark: Prevalence, Gestational Age, and Reasons

The slaughter of pregnant cattle gives rise to ethical controversy. We estimated the prevalence of pregnant cattle, elucidated the reasons for their slaughter, and in light of our findings, discussed the ethics of sending pregnant cattle for slaughter. Among 825 female cattle >353 days of age admitted to a Danish abattoir, 187 (23%) were found to be pregnant. There was no apparent difference in the proportion of pregnant animals between dairy and non-dairy cattle. "Health"-related slaughter was most frequent in dairy herds (70%), whereas "production"-related slaughter was most frequent in non-dairy herds (63%). While many farmers considered it unethical to slaughter pregnant cows without a good reason for doing so, many dairy farmers identified animal welfare as an important parameter in the decision, which was typically when the general condition of the cow or heifer would make it difficult for her to pass through calving and subsequent lactation. The many pregnant animals sent for slaughter were often the result of deliberate choices. Non-dairy farmers often kept a bull with their female cattle, and in many instances, this resulted in the mating of cattle intended for slaughter. Although considered ethically problematic by many dairy farmers, the slaughter of pregnant dairy cattle was often considered better for the cow compared to a stressful lactation period.

Exploring early human brain development with structural and physiological neuroimaging

Early brain development, from the embryonic period to infancy, is characterized by rapid structural and functional changes. These changes can be studied using structural and physiological neuroimaging methods. In order to optimally acquire and accurately interpret this data, concepts from adult neuroimaging cannot be directly transferred. Instead, one must have a basic understanding of fetal and neonatal structural and physiological brain development, and the important modulators of this process. Here, we first review the major developmental milestones of transient cerebral structures and structural connectivity (axonal connectivity) followed by a summary of the contributions from ex vivo and in vivo MRI. Next, we discuss the basic biology of neuronal circuitry development (synaptic connectivity, i.e. ensemble of direct chemical and electrical connections between neurons), physiology of neurovascular coupling, baseline metabolic needs of the fetus and the infant, and functional connectivity (defined as statistical dependence of low-frequency spontaneous fluctuations seen with functional magnetic resonance imaging (fMRI)). The complementary roles of magnetic resonance imaging (MRI), electroencephalography (EEG), magnetoencephalography (MEG), and near-infrared spectroscopy (NIRS) are discussed. We include a section on modulators of brain development where we focus on the placenta and emerging placental MRI approaches. In each section we discuss key technical limitations of the imaging modalities and some of the limitations arising due to the biology of the system. Although neuroimaging approaches have contributed significantly to our understanding of early brain development, there is much yet to be done and a dire need for technical innovations and scientific discoveries to realize the future potential of early fetal and infant interventions to avert long term disease.

On the feasibility of accessing acute pain-related facial expressions in the human fetus and its potential implications: a case report

Supplemental Digital Content is Available in the Text.

Introduction:

Although pain facial assessment is routinely performed in term and preterm newborns by the use of facial expression–based tools such as the Neonatal Facial Coding System, the assessment of pain during the intrauterine life has not been extensively explored.

Objective:

Describe for the first time, an experimental model to assess and quantify responses due to acute pain in fetuses undergoing anaesthesia for intrauterine surgery recorded by high-resolution 4D ultrasound machines.

Methods/results-case report:

A 33-year-old pregnant woman had congenital left diaphragmatic hernia of poor prognosis diagnosed, and her fetus was treated by fetoscopic endotracheal occlusion. Later, during the removal of the fetal endotracheal balloon by ultrasound-guided puncture, we have recorded facial expressions of the foetus before and after the anaesthetic puncture by the use of 4D ultrasound recordings, which were presented to 3 blinded coders instructed to use the Neonatal Facial Coding System for acute pain facial coding. The procedure was safe and feasible.

Conclusion:

This is the first description of a recordable acute pain model in the human fetus by the use of a facial expression–based tool. The possibility to assess pain-related intrauterine behaviours would allow not only for the monitoring of the efficacy of anaesthetic procedures in the fetus but would also open the way to explore the evolution of pain-related facial responses during the fetal neurodevelopment. This method may pave the way for objective assessments of pain in fetuses, should it endure the steps of formal validation studies.

Animal welfare aspects in respect of the slaughter or killing of pregnant livestock animals (cattle, pigs, sheep, goats, horses)

This scientific opinion addresses animal welfare aspects of slaughtering of livestock pregnant animals. Term of Reference (ToR) 1 requested assessment of the prevalence of animals slaughtered in a critical developmental stage of gestation when the livestock fetuses might experience negative affect. Limited data on European prevalence and related uncertainties necessitated a structured expert knowledge elicitation (EKE) exercise. Estimated median percentages of animals slaughtered in the last third of gestation are 3%, 1.5%, 0.5%, 0.8% and 0.2% (dairy cows, beef cattle, pigs, sheep and goats, respectively). Pregnant animals may be sent for slaughter for health, welfare, management and economic reasons (ToR2); there are also reasons for farmers not knowing that animals sent for slaughter are pregnant. Measures to reduce the incidence are listed. ToR3 asked whether livestock fetuses can experience pain and other negative affect. The available literature was reviewed and, at a second multidisciplinary EKE meeting, judgements and uncertainty were elicited. It is concluded that livestock fetuses in the last third of gestation have the anatomical and neurophysiological structures required to experience negative affect (with 90-100% likelihood). However, there are two different possibilities whether they perceive negative affect. It is more probable that the neurophysiological situation does not allow for conscious perception (with 66-99% likelihood) because of brain inhibitory mechanisms. There is also a less probable situation that livestock fetuses can experience negative affect (with 1-33% likelihood) arising from differences in the interpretation of the fetal electroencephalogram, observed responses to external stimuli and the possibility of fetal learning. Regarding methods to stun and kill livestock fetuses at slaughter (ToR4), sets of scenarios and respective actions take account of both the probable and less probable situation regarding fetal ability for conscious perception. Finally, information was collated on methods to establish the dam's gestational stage based on physical features of livestock fetuses (ToR5).

Current status of fetal neurodevelopmental assessment: Four-dimensional ultrasound study

With the latest advent of four-dimensional (4-D) ultrasound, fetal neurobehavioral or neurodevelopmental assessment can be easily and readily performed. Using this technique, typical fetal movements and behavioral patterns have become apparent in all three trimesters of pregnancy. In twin pregnancy, 4-D ultrasound facilitates the precise evaluation of inter-twin contact and intra-pair stimulation. New fetal neurobehavioral assessment tests, such as Kurjak's Antenatal Neurodevelopmental Test and the Fetal Observable Movement System, may reflect the normal and abnormal neurological development of the fetus, and will facilitate more precise assessments of fetal neurobehavior or neurodevelopment, and fetal brain and central nervous system functions. In this review article, I also discuss interesting topics regarding maternal and fetal stress, fetal pain, and fetal consciousness. Four-dimensional ultrasound has opened the door to new scientific fields, such as 'fetal neurology' and 'fetal psychology,' and fetal neurobehavioral science is at the dawn of a new era. Knowledge on fetal neurobehavior and neurodevelopment will be advanced through fetal behavioral research using this technique.

The Cellular and Molecular Landscapes of the Developing Human Central Nervous System

The human CNS follows a pattern of development typical of all mammals, but certain neurodevelopmental features are highly derived. Building the human CNS requires the precise orchestration and coordination of myriad molecular and cellular processes across a staggering array of cell types and over a long period of time. Dysregulation of these processes affects the structure and function of the CNS and can lead to neurological or psychiatric disorders. Recent technological advances and increased focus on human neurodevelopment have enabled a more comprehensive characterization of the human CNS and its development in both health and disease. The aim of this review is to highlight recent advancements in our understanding of the molecular and cellular landscapes of the developing human CNS, with focus on the cerebral neocortex, and the insights these findings provide into human neural evolution, function, and dysfunction.

Slaughter of pregnant cattle in German abattoirs--current situation and prevalence: a cross-sectional study

Background

The slaughter of pregnant cattle and the fate of the foetuses are relatively new subjects in the field of animal welfare. The Scientific Committee on Veterinary Measures relating to Public Health (SCVPH), however, does not believe this topic to be a critical issue because of the hitherto supposed rare occurrence of this practice. Some previous studies though, contradict this assessment, emphasising its relevance to animal welfare. With regard to the heterogeneous study design of previous investigations, the objective of this study is to evaluate the current situation concerning the slaughter of pregnant cattle in different German abattoirs. Additionally, the prevalence was assessed semi-quantitatively on the basis of a cross-sectional, voluntary and anonymous survey that was conducted amongst senior veterinary students of the University of Leipzig from 2010 until 2013.

Results

Of 255 evaluable questionnaires, 157 (63.6 %) mention the slaughter of pregnant cattle, corresponding to 76.9 % of all visited abattoirs. Slaughter of pregnant cattle is reported often (>10 % of females) in 6 (3.8 %), frequently (1–10 % of females) in 56 (35.7 %), and rarely (<1 % of females) in 95 (60.5 %) of all cases (n = 157) respectively. About 50 % of these animals were reported to be in the second or third stage of gestation. 15 (10.6 %) of 142 questionnaires providing information about the foetus, state that the foetus showed visible vital signs after the death of the mother, but in one case the foetus was euthanized subsequently.

Conclusions

The results show that the slaughter of pregnant cattle is a common and widespread practice in German abattoirs. The SCVPH’s assumption that pregnant cattle are only slaughtered in rare exceptional cases can no longer be maintained. The high proportion of foetuses in the second and third gestational stage must also be considered. In this context the implementation of suitable studies and detailed analysis of the current situation is indispensable to ensure the high standards in animal welfare in Germany and Europe.

Use of fetal analgesia during prenatal surgery

OBJECTIVE

Recent progresses in fetal surgery have raised concern on fetal pain, its long-term consequences and the risks of sudden fetal movements induced by pain. In several studies, surgeons have directly administered opioids to the fetus, while others have considered sufficient the maternally administered analgesics. We performed a review of the literature to assess the state of the art.

METHODS

We performed a PubMed search to retrieve the papers that in the last 10 years reported studies of human fetal surgery and that described whether any fetal analgesia was administered.

RESULTS

We retrieved 34 papers. In three papers, the procedure did not hurt the fetus, being performed on fetal annexes, in two papers, it was performed in the first half of pregnancy, when pain perception is unlikely. In 10 of the 29 remaining papers, fetal surgery was performed using direct fetal analgesia, while in 19, analgesia was administered only to the mother. In most cases, fetal direct analgesia was obtained using i.m. opioids, and muscle relaxant. Rare drawbacks on either fetuses or mothers due to fetal analgesia were reported.

CONCLUSION

Fetal direct analgesia is performed only in a minority of cases and no study gives details about fetal reactions to pain. More research is needed to assess or exclude its possible long-term drawbacks, as well as the actual consequences of pain during surgery.

Pain assessment in human fetus and infants

In humans, painful stimuli can arrive to the brain at 20-22 weeks of gestation. Therefore several researchers have devoted their efforts to study fetal analgesia during prenatal surgery, and during painful procedures in premature babies. Aim of this paper is to gather from scientific literature the available data on the signals that the human fetus and newborns produce, and that can be interpreted as signals of pain. Several signs can be interpreted as signals of pain. We will describe them in the text. In infants, these signs can be combined to create specific and sensible pain assessment tools, called pain scales, used to rate the level of pain.