There is widespread belief and extensive anecdotal evidence that sense of smell (olfaction) is heightened during pregnancy, but the scientific literature is limited and inconclusive.  Heightened sense of smell is believed to be important to protect the developing fetus and may be associated with morning sickness. The standard methods used to measure olfactory function may not have been sensitive enough to reveal differences between pregnant and non-pregnant women or may not have used appropriate stimuli.  This study compares the performance of pregnant and non-pregnant women on a battery of novel olfactory perception tasks and on self-reported nausea and vomiting.  We expect to recruit at least 20 pregnant women in each trimester and 20 non-pregnant women between the ages of 18 and 45 years.  The tasks are: (1) Detection threshold tasks with a food odor (amyl acetate, i.e., banana) using both a standard staircase method and the method of constant stimuli, which uses a predetermined range of odor concentrations and from which a psychometric function can be generated.  Both tasks employ a 2-alternative forced-choice method with the participant indicating which of two stimuli seems stronger. (2) The Suprathreshold Odor Rating Task, in which participants rate the intensity and pleasantness of amyl acetate at four concentrations above threshold. (3) Two tests of short-term odor memory.  The first is the standard scratch and sniff Odor Memory Test, in which the participant smells one of 4 common odors and after a delay of 10, 30 or 60 seconds indicates which odor they remember in 4-alternative forced-choice task. The second is a newly-developed task of memory for common and uncommon odors after a 30 second delay (Cameron, Köster & Møller, 2017).  After the delay the participant indicates whether a stimulus was the same as one she smelled previously. Signal detection analysis is applied to explore hit, false alarm and correction rates for odors that are within or across odor category. Women also complete the Pregnancy-Unique Quantification of Emesis (PUQE) Scale, a measure of self-reported nausea and vomiting.   Testing is underway. A series of 1 and 2-way Analyses of Variance will be used to examine the effects of the quasi-independent (pregnancy status) and independent variables (odor concentration, delay and odor type) specific to each task. We expect these new methods to reveal enhanced performance in pregnant women compared to non-pregnant controls, and hypothesize that nausea and vomiting may be correlated with enhanced olfactory performance.