The thing about chronic pain is that it ramps up the nervous system, which in turn surpresses respiration making breathing shallower.
This is especially destructive with CPP as deep respiration and calming the nervous system are pivotal to lowering pain levels and helping treat the underlying problem.
posture also plays a major role. When a woman feel pain in her pelvic region she tends to round forward over the area to protect it. Breathing thus becomes shallow as your diaphragm and lungs cannot function correctly.
Try standing up straight and breathing into your diaphragm now round your shoulders and stoop forward and try it again- feel how different it is!
Not breathing properly decreases movement in the abdominals and pelvic floor.