Did you know that when having a vaginal birth, the tailbone needs to be able to extend? This creates more space at the pelvic outlet and allows the pelvic floor muscles to elongate because they attach to the tailbone. Anatomically it supports one of the reasons behind why lying on your back might not be the most beneficial for your pelvic floor and birth.
For many women once they see and understand this concept, they are able to strengthen this mind body connection that is so valuable during birth. This is why I always show patients where their tailbone is, encourage them to feel it, and to understand that it is able to extend as we let go of tension in the pelvic floor muscles. They can take this into birth and are then able to feel that space created when squatting, standing or even side lying.