We aimed to investigate auditory cognitive and behavioral functions during mid trimester pregnancy using Event-Related Potentials (ERPs) and neuropsychological tests, respectively. ERPs were studied by using 128-sensor net and PAS, WCST, RAVLTIM, RAVLTDR and RAVLTTS were tested for neuropsychology assessment. Total 18 subjects were recruited (n=9 in each group; control and pregnant group; 16-27 weeks). Auditory oddball paradigm was used during ERP study. Subjects counted silently only target stimuli with giving attention by ignoring standard stimuli. Value of the mean differences of the target and standard stimuli were measured across groups in six locations. The N100 and The P300 ERP components were recorded at T3, T4, T5, T6, Cz and Pz electrode sites. Higher amplitudes (4/6) and prolonged latencies (4/6) of the N100 component were found. Shorter amplitudes (1/6) and longer latencies (3/6) of the P300 component were found in the pregnant group compared to the control group. No significant difference in scores of PAS, WCST, RAVLTDR and RAVLTTS among both groups. Significantly higher RAVLTIM was observed in pregnant group. We concluded that there is mild auditory cognitive impairment during second trimester pregnancy without any deficit in executive function and auditory memory.