Voice Changes During Pregnancy Trimesters in Iranian Pregnant Women

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 (VHI_P). 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 VHI_P-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 VHI_P-30 score noticeably occurred during the third trimester. The results suggest significant vocal changes toward less stable phonation during the third trimester of pregnancy.