It is well known that parity affects the human skeleton through biomechanical strain during pregnancy and birth, lactation, and sexual steroid hormone expression. Pelvic features are bony exostoses and lesions found on the pelvis and are frequently interpreted as parturition scars, although the direct causal factors remain unclear. In this study, we created a weighted pelvic pattern index (PPI) by combining all pelvic features (preauricular sulcus, dorsal pubic pitting, extended pubic tubercle, ventral pubic pitting & exostoses, margo auricularis groove, sacral preauricular extension & notch) to statistically evaluate its association with parity in three samples (one modern, and two from the 19th century). The PPI was significantly associated with parity and age at death. A pelvis shape analysis revealed an association with an increase in pelvic width. However, bone modelling in older women weakened the association of the PPI with parity. The PPI showed differences between the modern and historical samples, suggesting that factors such as lifestyle and obstetrical practices affect the relationship between the PPI and actual parity. We propose the PPI as a useful tool for assessing parity, but the predictive accuracy may vary across populations. We present a software tool for an easy application of the PPI in bioarcheological and anthropological studies.