An assessment of pain responses to thermal stimuli during stages of pregnancy.

A study utilizing visual analogue scale (VAS) responses to 43-51 degrees C nociceptive thermal stimuli was carried out to determine whether women demonstrate a change in pain responsiveness across stages of pregnancy. Fifteen women tested in late pregnancy, labor, and post partum showed no significant differences in VAS responses to thermal stimuli across these stages. The results indicate that no central pain inhibitory system is active during late pregnancy or labor.