To review evidence regarding the presence of fetal pain and its points of contention within the scientific community.

The study of fetal pain is fairly new, but has attracted controversy in light of abortion availability and advances in fetal surgery. This has led to disputed claims being presented as scientific fact throughout the public sphere. This project will present the field’s current state through review of available literature.

English-language articles with human subjects focusing on fetal pain, analgesia, and anesthesia were acquired via PubMed and reviewed for additional references. The search was without date limitations and current as of October 21, 2018. Eleven articles were accepted.

Within the field, pain is defined as nociception plus the ability to emotionally interpret noxious stimuli as unpleasant, thereby requiring consciousness. Beyond this, disagreement emerges, starting with nociceptive pathways and their required neuroanatomy. While the thalamus and cortical subplate have their proponents, the majority of authors posit the cortex as the final necessary piece, placing the earliest potential for pain sensation at 23-30 weeks gestational age. However, consciousness remains an issue, debate continuing as to whether fetuses are naturally sedated within the womb. This would make perception of pain impossible prior to birth, if not later. In all, the continued discord stems from the difficulty of measuring subjective experience in non-verbal subjects, necessitating indirect methods. All forms so far proposed, such as fetal movements/expressions, physiologic stress response, or EEG monitoring, have faced heavy criticism from one side or the other.

The study of fetal pain is complicated by definitional disputes and limitations inherent to its subjects. While general consensus on the need, at least, for intact thalamic nociceptive connections suggests its presence prior to the third trimester is unlikely, widespread debate persists and will require further research into all avenues of this field.