During pregnancy, especially in late pregnancy, women experience ligamentous relaxation of the pubic symphysis due to hormonal changes to facilitate smooth descent of the fetal head.
The growth of the foetus in late pregnancy shifts the woman’s body weight forward resulting in increased pelvic pressure. Some pregnant women have pathologically weak pelvic ring structures, which can lead to separation of the pubic bone.
During labour, if there is an oversized foetus, a pregnant woman’s pelvis is too small, fetal malposition, and roughly assisted labour, the pubic symphysis can be subjected to abnormal mechanical compression at the pubic symphysis, leading to a rupture of the pubic symphysis and separation of the pubic bone.