Of course the fact that some animals, even ones as advanced as fishes, don't appear to feel pain either doesn't stop the same utilitarians from use the pleasure/pain argument when arguing in favor of animal rights. But then again, logical inconsitency is the stock in trade of Peter Singer types.
"Administering anesthesia directly to the fetus is also sometimes done but generally to reduce the release of potentially harmful fetal stress hormones (search), Rosen (Nazi scientist) said. There is little research on its effects, the authors said."
Well the release of fetal stress hormones, which is measurable, is a direct result of pain. Babies earlier than 20 weeks have been found to release these hormones when stuck with a needle in utero. It's observable and measurable. Now tell me why should anybody trust a scientist if the scientific community doesn't reject this meta study laced with bs?