Does the Unborn Baby Feel Pain?

Dr Nalini Pather
technological advancements have given us a window into the life of the unborn child. The growth and development of a baby in-utero is fascinating and awesome. By the end of eight weeks (the embryonic period) most organs in the body have formed. There is a substantial body of scientific evidence supporting the claim that the unborn baby can feel pain too. The sensation of pain is mediated by the nervous system. To experience pain, pain receptors must be present, and these receptors must be connected to the cerebral cortex of a functioning brain. All three of these (pain receptors, connection to the brain, and brain function) have good scientific evidence showing that they are established early in development. Firstly, studies have shown that pain receptors (nociceptors) are present by ten weeks. According to Brusseau (2008), ‘The first essential requirement for nociception is the presence of sensory receptors, which develop first in the perioral area at around 7 weeks’ gestation. From here, they develop in the rest of the face and in the palmar surfaces of the hands and soles of the feet from 11 weeks. By 20 weeks, they are present throughout all of the skin and mucosal surfaces’. Secondly, the connection between these nociceptors and the brain via the spinal cord is present at 8 weeks. ‘From 16 weeks’ gestation, pain transmission from a peripheral receptor to the cortex is possible and completely developed from 26 weeks’ gestation.’ (Van de Velde and De Buck, 2012, p206). Thirdly, electrical brain activity, which is a sign of a functioning brain, can be recorded as early as 43 days in-utero.

Besides having the network for pain, a baby in utero is able to respond to stimuli such as sound, light and touch. Intra-uterine surgery has shown that the baby recoils or reacts to sharp objects and incisions. ‘A motor response can first be seen as a whole body movement away from a stimulus and observed on ultrasound from as early as 7½ weeks’ gestational age’ (Myers and colleagues, 2004). When pain is experienced, it triggers a stress response, which can be detected by analysing circulating stress hormones in the blood. Fetal surgical procedures have shown that these hormones, accompanied by vigorous movements, occur independently from the mother when a painful stimulus is added (Gupta and colleagues, 2008). In a testimony before the US Congress, the obstetrician, David Birnback said ‘Having administered anesthesia for fetal surgery, I know that on occasion we need to administer anesthesia directly to the fetus, because even at these early gestational ages the fetus moves away from the pain of the stimulation’. These experiences of pain in-utero can be associated with long-term postnatal effects. Clinical practice is increasingly recognising pain in the unborn and recognising the need for adequate management of fetal pain during therapeutic intra-uterine procedures as voiced by Van de Velde (2006). ‘It is becoming increasingly clear that experiences of pain will be ‘remembered’ by the developing nervous system, perhaps for the entire life of the individual. These findings should focus the attention of clinicians on the long-term impact of early painful experiences, and highlight the urgent need for developing therapeutic strategies for the management of neonatal and fetal pain.’ Although we don’t know when exactly the fetus begins experiencing pain, there is overwhelming evidence that the fetus possesses the neural networks needed for pain sensations very early in development; and moreover, has a response to pain that can have lasting postnatal effects on brain and behaviour development.

References:
Gupta R, Kilby M, Cooper G. Fetal surgery and anaesthetic implications. Continuing Education in Anaesthesia, Critical Care & Pain. 8:2 (2008) 71-75:74

Brusseau R. Developmental Perspectives: is the Fetus Conscious? International Anesthesiology Clinics. 46:3 (2008) 11-23.

Marc Van de Velde & Frederik De Buck, Fetal and Maternal Analgesia/Anesthesia for Fetal Procedures. FetalDiagnTher 31(4) (2012) 201-9:206

Myers LB, Bulich LA, Hess, P, Miller, NM. Fetal endoscopic surgery: indications and anaesthetic management. Best Practice & Research Clinical Anaesthesiology. 18:2 (2004) 231-258:241

Van de Velde M, Jani J, De Buck F, Deprest J. Fetal pain perception and pain management. Seminars in Fetal & Neonatal Medicine. 11 (2006) 232-236:234

Dr Nalini Pather is a medical scientist and lecturer at the University of NSW.