Coccydynia Exacerbates Quality of Life, Functional, and Neuromuscular Dysfunction in Third Trimester Pregnancy-Related Pelvic Girdle Pain: A Cross-Sectional Study

Objective To compare third-trimester pregnant individuals with pelvic girdle pain (PGP) alone versus those with both PGP and coccydynia in terms of quality of life (QoL), functional mobility, pelvic floor muscle activation, and sleep quality. Methods This cross-sectional study included 64 pregnant individuals with pregnancy-related pelvic girdle pain (PGP), comprising two equal groups: 32 with concomitant coccydynia (PGP + C group) and 32 without coccydynia (PGP-only group). Participants completed the Pelvic Girdle Questionnaire (PGQ), Oswestry Disability Index (ODI), Pittsburgh Sleep Quality Index (PSQI), and World Health Organization Quality of Life – Brief Form (WHOQOL-BREF). Pelvic floor muscle activity was assessed using surface electromyography (EMG) during maximal voluntary contraction. Results The PGP + C group had significantly lower physical (p = 0.034, d = 0.54) and psychological (p = 0.044, d = 0.51) QoL scores, and higher levels of disability (ODI, p = 0.036), symptom burden (PGQ, p = 0.009), and sleep disturbance (PSQI, p = 0.006). Contraction-phase EMG activity was reduced (p < 0.001, d = 1.05), while resting EMG was elevated (p < 0.001, d = 0.89). PGQ strongly correlated with QoL, disability, EMG activity, and sleep (all p < 0.001), with stronger associations than in the PGP-only group. Regression analyses identified PGQ as the only consistent predictor of all outcomes (adjusted R²: 0.463–0.773; all p < 0.05), whereas VAS was not significant. Conclusion Coccydynia contributes to greater physical and functional burden in individuals with pregnancy-related PGP. However, perceived functional impairment rather than pain severity appears to be the primary driver of reduced neuromuscular and QoL outcomes. These findings highlight the importance of function-centered assessment and intervention strategies in this population.