Research Article| Volume 34, ISSUE 3, P358-363, May 2020

Voice Changes During Pregnancy Trimesters in Iranian Pregnant Women

Published:November 01, 2018DOI:



      This study aimed to evaluate the vocal changes in the Iranian pregnant women according to trimesters both objectively and subjectively.


      There were 93 pregnant women and 31 non-pregnant women participants in the study. Thirty-three of the 93 pregnant women were in their first trimester, 31 in their second trimester, and 29 in their third trimester of their pregnancies. Clinical data were collected from the acoustic measurements, aerodynamic assessment, video laryngoscopy examination, and the self-assessment of quality of life related to voice using the Persian Voice Handicap Index (VHIP). The analysis of variance (ANOVA) test and Kruskal–Wallis test were used for between-group comparisons of the data.


      Decreased maximum phonation time (MPT), increased S/Z ratio, increased VHIP-30 scores, and evidence of vocal fold edema were the parameters that differed significantly only in the third trimester. Acoustic analysis revealed that F0, jitter, shimmer, and noise-to-harmonics ratio (NHR) were not significant across the four groups.


      Results showed that decreased MPT, increased S/Z ratio, mild to moderate edema, and a deterioration of the VHIP-30 score noticeably occurred during the third trimester. The results suggest significant vocal changes toward less stable phonation during the third trimester of pregnancy.

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      Hamide Ghaemi is Ph.D. of Speech and Language Pathology in Mashhad University of Medical Sciences and Assistant Professor in Education Council in Faculty of Paramedical Sciences – Mashhad University of Medical Sciences.


      Ali Dehqan, Ph.D., is an Assistant Professor and Head of Department in the Department of Speech Therapy at Zahedan University of Medical Sciences, Zahedan, Iran. His main research interests relate to the acoustics and aerodynamics of speech, laryngeal manual therapy, and professional voice production.


      Behrooz Mahmoudi-Bakhtiari, Ph.D., is a Professor in the University of Tehran, Department of Performing Arts, and Faculty Member. His main areas of research are teaching Persian to foreigners, Iranian dialectology and linguistics, and linguistic/semiotic approaches to drama and film.


      Ronald C. Scherer is a Professor of communication sciences and disorders in Bowling Green State University. He has earned an international reputation for his pioneering work on the aerodynamic and acoustics of the human vocal tract.