The effect of pregnancy on the middle ear acoustic features

ABSTRACT To determine the changes in air resonance frequency in pregnancy and get information to ease to assess the pregnant patients in possible pathologic states and provide new data for the literature. A total of 89 patients 46 of whom were third trimester pregnant woman (27-40 weeks) on follow up of Baskent University Gynecology and Obstetrics Department and 43 of whom were voluntary subjects as the control group were enrolled in the study between July and December 2013 in Başkent University Hospital KBB (Otorhinolaryngology) Clinic. The patients were performed otoscopy by an otorhinolaryngologist and their threshold of hearing were determined by pure-tone audiometry. Airway hearing thresholds were measured using TDH-39 Standard earphone between 250-8000 Hz frequency in silent cabins. Bone-conducted hearing thresholds were measured in 500-4000 Hz and immitansmetric measurements were performed by Grason-Stadler (GSI) tympstar version 2 electroacoustic immitansmeter. % 52.2 of the pregnant women attending the study were above 32 weeks. Both two ear 250 Hz and 500 Hz frequency audiometry values were significantly higher in pregnant group. No differences were detected between pregnant and control groups' both two ear 1000 Hz and above frequency audiometry values and pure-tone values. Both two ear resonance values were significantly lower than the control group. A negative correlation was observed betweeen the weight put on and resonance values of left ear. No difference was observed for both right and left ear between pregnancy weeks and resonance values. There are many theories and mechanisms defined about changes in hearing due to physiologic alterations of pregnancy. To assess these mechanisms and to establish more certain relations, extensive studies with large number of pregnant women and regular follow up are required. Keywords: Pregnancy, hearing, resonance frequency, multifrequency tympanometry.