Results
Overall pregnant women had a significantly straighter and more posteriorly oriented coccyx when compared to nulliparous women. This was reflected by a change in 3 measures at the univariate level. The coccygeal curvature index was higher in pregnant (89.2 ± 10.0) women relative to nulliparous (78.7 ± 6.6, p=0.003) and parous (80.0 ± 5.5, p=0.004) women. The sacrococcygeal curvature index and sacrococcygeal angle also increased in the pregnant as compared to the nulliparous group (73.3 ± 5.8 versus 79.2 ± 3.7, p=0.016; 92.8° ± 10.9° versus 109.3° ± 9.4°, p=0.002, respectively) with no difference between pregnant and parous groups for these measurements.