Do low levels of labour pain reflect low sensitivity to noxious stimulation?

In a study investigating factors affecting labour pain, 10 out of 97 subjects reported that they had never experienced any pain outwit childbirth. These subjects experienced comparatively low levels of pain within childbirth. They did not differ significantly from the majority of subjects on a large number of obstetric and psychological factors which normally affect pain in labour. It was suggested that these subjects were relatively insensitive to noxious stimulation, in that they do not experience pain when noxious stimulation is mild or moderate (as for example a consequence of menstruation, common accidents or ailments) and experience lower than average levels of pain when noxious stimulation is intense as in labour. Further investigation of such subjects is of theoretical interest and practical importance since it might allow for accurate prediction of pain levels in a proportion of parturants.