Here are some more links having to do with the perception of pain and neurological development of the human during pre-natal development (I knew I had them, since I testified for the Fetal Pain Act at the Texas House State Affairs Committee last month):
http://www.prochoiceforum.org.uk/comm53.asp ""Fitzgerald has reviewed the biological development of the fetus and examined the possibility of fetal pain at each stage of development. The impression that a fetus experiences sensation is apparent at 7.5 weeks gestation when reflex responses to somatic stimuli begin. At this point touching the peri-oral region results in a contralateral bending of the head. The palms of the hands become sensitive to stroking at 10.5 weeks and the rest of the body and hindlimbs become sensitive at approximately 13.5 weeks. Shortly after the development of sensitivity, repeated skin stimulation results in hyperexcitability and a generalized movement of all limbs. This hyperexcitability has been interpreted as evidence for the presence of a functional pain system, reflecting an immature but intact pain response with early hypersensitivity to stimulation (14).""
(Although, since the definition of pain is clinically differentiated from the definition of stress response, these reactions are not called "pain" responses until later in gestation. But, it looks like the embryo or fetus is reacting as you or I would to pain.)
http://www.med.ic.ac.uk/divisions/58/perinatal_stress.asp ""Fetal stress responses
We have now completed our first trial of giving the opiate fentanyl to the fetus. These are the first experiments to determine how to give pain relief to the fetus in a safe and effective way. At the doses used it ablated the blood flow redistribution to the brain, and the endorphin response but not the cortisol response.
We are continuing to characterise how the fetus responds to therapeutic but possibly painful invasive procedures, such as a blood transfusion. It can mount a rapid noradrenaline response from 18 weeks gestation and a slower cortisol and ß-endorphin response at least from 20 weeks. It also responds by increasing blood flow to the brain. This has been demonstrated from 16 weeks.""
http://www.nrlc.org/news/2000/NRL09/ranalli.html ""The authority Dr. Glover brings to the debate makes it difficult for the RCOG, and the general public, to ignore her concerns. The RCOG Working Party referenced one of the key fetal pain research projects she published in 1994 with Dr. Nicholas Fisk and colleagues.
Their research revealed that, in response to a painful procedure, fetuses as early as 19 weeks release large amounts of pain and stress hormones into the fetal bloodstream, the same hormonal surge that occurs in adults. An earlier study by German researcher Dr. Joachim Partch detected similar hormones in the surrounding amniotic fluid as early as 16 weeks into the pregnancy.""