Pregnant women exhibit decreased trigeminal sensitivity.

Introduction: Chemosensory function in pregnant women is far from being fully understood due to the lack of data and inconsistencies between the results of self-reports and objective studies.

Methods: In the present study in pregnant and non-pregnant women (n = 14, n = 13), we measured EEG-derived electrophysiological response measures supported by psychophysical olfactory and trigeminal tests.

Results: Results indicate that the olfactory event-related potential amplitudes or latencies of the P1, N1, and P2 components remain unchanged in pregnant women. In accordance with these findings, no difference was observed between pregnant and non-pregnant women in psychophysical olfactory tests. However, pregnant women displayed a lower degree of sensitivity to trigeminal stimuli compared to non-pregnant controls, which was also reflected in the electrophysiological responses to trigeminal stimuli.

Conclusion: Counterintuitive as they may seem, our findings demonstrate a "flattening" of chemosomatosensory responses. Psychological processes occurring during pregnancy, such as changes in socioemotional perception of odors resulting from the diminished stress response, may provide a background to these results. Overall, the present results indicate the absence of major differences between non-pregnant and pregnant women in terms of measured olfactory function though chemosomatosensory function of the pregnant women appears to be decreased.