The first thing I noticed was how the researchers obtained studies and what limitations they put on them specifically, "The search was performed without date limitations and was current as of June 6, 2005."
I find this interesting because without date limitations means that many studies from the 1960's and 1970's might be included in this review of studies. Why is this interesting? Because the realization that newborn infants feel pain is a fairly new rediscovery in the scientific community. In a newsletter for the American Society of Anesthesiologists, Dr. Doris Cope notes,
Such entrenched theory dies hard, so that as late as 1968, surgeons L.I. Swafford, M.D., and D. Allen, M.D., contended, "Pediatric patients seldom need medication for the relief of pain after general surgery. They tolerate discomfort well."(emphasis mine)
The idea of infants not experiencing pain after noxious stimuli was still prevalent in conventional wisdom as seen in the popular press. There was no clearer demonstration of this than in the advice given to parents circumcising their male newborns. In 1982, Proctor and Gamble promoted Pampers to parents by providing Expectant Parents' Information Kits, which included the statement: "You may be surprised to learn that circumcision will not be painful to your baby because, at this early stage of development, the penis does not yet have functioning pain nerve endings." Mother's Manual, published the same year, argues against local anesthesia for circumcision: "It swells the area to the extent of making an unsatisfactory circumcision too likely."
Medical opinion began to change in the 1980s. Studies in neonatal pain measured behavioral, physiologic and biochemical responses to pain. While the behavioral changes had been explained as simple learned reflexes, the changes in physiological parameters and O2 saturation after endotracheal intubation were more difficult to explain. Perhaps the most convincing studies demonstrating the real phenomenon of neonatal pain were a series of papers, published in the late 1980s, showing the hormonal and metabolic responses in infants undergoing surgery that were attenuated by general anesthesia. Since that time, numerous pain scales have been proposed to assess pediatric pain.
Today, the concept of neonatal and pediatric pain is well-established, and the lesson to be learned by the medical community is the need for caution in applying experimental findings in isolated animal proposals and philosophical theorems to clinical practice. It is ironic to note that at one time in our medical history, a simple unlettered parent could more accurately diagnose pain in their infant child than the most advanced experimental scientist or state-of-the-art philosopher.
I would also point out that it seems the researchers limited their meta-analysis to studies with unborn children and didn't include pain studies on children who were born before 30 weeks. Wouldn't it be much easier to study the possibility of pain in a born child who is premature than it would in an unborn child?
Also of note is how the researchers define pain: "Pain perception requires conscious recognition or awareness of a noxious stimulus. Neither withdrawal reflexes nor hormonal stress responses to invasive procedures prove the existence of fetal pain, because they can be elicited by nonpainful stimuli and occur without conscious cortical processing. Fetal awareness of noxious stimuli requires functional thalamocortical connections."
They define pain and the perception of pain to their own desires and simply brush aside the behavioral evidence.
This meta-analysis seems less like a scientific study and more like a hit piece designed to get headlines and provide cheapshot commentary on prolife legislation.