Abstract: Objective: Does TMJ nociception, as measured by a behavioral assay, differ during pregnancy, potentially due to the effect of sex steroids? Methods: Thirty-two Sprague Dawley rats were randomly allocated to either mid- (E11) or late- (E17) pregnancy groups. The animals within each group were further allocated to a saline or CFA treatment. At E11 or E17, the animals were injected bilaterally into TMJ with either saline (15 μL) or 1 μg/ μL CFA (15 μL). Nociception was measured with a feeding assay (pellet recording) and analyzed by comparing intra-meal rates using a distance-based permutation method. Results: CFA injection resulted in the animals eating longer in both the mid-pregnant and late-pregnant groups. Plasma estradiol was higher in the late-pregnant group versus the mid-pregnant group. Importantly, the CFA injected late-pregnant group ate for a shorter amount of time (i.e., shorter meal rate) than the CFA injected rats at mid-pregnancy. Conclusion: The reduced nociceptive response (shorter meal rate) in the CFA injected late-pregnant group may be due to greater estradiol versus the CFA injected mid-pregnancy rats. Thus, one potential reason why women report fewer TMJ symptoms during pregnancy is the higher level of circulating estradiol.