Impact of coccydynia on quality of life, function, and neuromuscular control in women with third trimester pelvic girdle pain: a cross-sectional study

Pelvic girdle pain during pregnancy is a common condition that negatively affects physical function and quality of life (QoL), particularly in the third trimester. Coccydynia may coexist with pelvic girdle pain and further increase functional and neuromuscular burden; however, its additional impact in pregnant individuals remains insufficiently explored. To compare QoL, functional disability, pelvic floor muscle activation (PFMA), and sleep quality between third-trimester pregnant women with pelvic girdle pain alone and those with pelvic girdle pain accompanied by coccydynia. This cross-sectional study was conducted between April and July 2025 in obstetrics outpatient clinics in Kayseri, Türkiye, and included third-trimester pregnant women diagnosed with pregnancy-related pelvic girdle pain. Sixty-four third-trimester pregnant women with pregnancy-related pelvic girdle pain were clinically stratified into two groups: pelvic girdle pain with coccydynia (PGP + C) (n = 32) and pelvic girdle pain without coccydynia (PGP) (n = 32). QoL was assessed using the World Health Organization Quality of Life–Brief Form, functional disability using the Oswestry Disability Index and the Pelvic Girdle Questionnaire, sleep quality using the Pittsburgh Sleep Quality Index, and PFMA using normalized surface electromyography during maximal voluntary contraction. Between-group comparisons were performed using independent-samples tests, and associations were examined using correlation and multiple linear regression analyses. The mean age was 30.18 ± 6.15 years in the PGP + C and 29.34 ± 5.27 years in the PGP. Compared with pelvic girdle pain alone, participants with coccydynia had lower physical QoL scores (mean difference − 11.40; 95% confidence interval − 21.90 to − 0.91; p = 0.034) and psychological QoL scores (p = 0.044), as well as higher disability, symptom burden, and poorer sleep quality (all p < 0.05). PFMA during contraction was reduced and resting muscle activity was increased in the PGP + C (p < 0.001). Functional symptom burden was the only consistent independent predictor of all outcomes, whereas pain intensity was not significant. Coccydynia is associated with greater functional, neuromuscular, and quality of life impairment in pregnant women with pelvic girdle pain. Functional limitation appears to be a more important determinant of clinical outcomes than pain intensity. This study evaluates how coexisting coccydynia impacts function, quality of life, and pelvic floor activation in third-trimester pregnant individuals with pelvic girdle pain.