Responsiveness to laboratory pain in women as a function of age and childbirth pain experience

Pain responsiveness was investigated experimentally as a function of age and childbirth pain experience. Sensitivity to cold pressor-induced pain was assessed through threshold, tolerance, and visual analog pain ratings. It was hypothesized that childbirth pain experience would mostly modify experimental pain judgment, in accordance with the adaptation-levels model. That is, childbirth pain would be used as an "anchor" in evaluating other painful events. Fifteen parous women were compared to 12 nulliparous women of the same age (mean age: 35 years) as well as to 15 nulliparous younger women (mean age: 24 years). This comparison was undertaken in order to distinguish the effects of age, which was found to correlate with pain threshold. Analysis of variance comparing the three groups of women was performed on each of the three cold pressor measures. A significant effect was found for pain threshold. Multiple comparisons indicated that parous women had a higher pain threshold than both groups of nulliparous women which did not differ from one another. Thus, painful childbirth experience is sufficient to raise cold pressor pain threshold. This finding has never before been reported in the pain literature. It is consistent with anecdotal reports from parous women who, when providing cold pressor pain judgments, say that "nothing compares to labor pain."