Pressure in labour can be heavenly, it can help to ease discomfort hugely. The important thing is to apply pressure wisely and where it is needed.
Remember the pelvis is like a clothes peg, you squeeze the top it opens the bottom, you squeeze the bottom, it opens the top.
If you take a broad contact at the top part of the pelvis and squeeze, it opens the bottom of the pelvis.
If you take a broad contact lower on the pelvis towards the hollow part at the bottom of the buttocks and squeeze, it will slightly gap the top of the pelvis.
You can contact the sitting bones or ischial tuberosities and apply pressure to them. If you alternate the pressure one side and then the other it can relieve pelvic floor discomfort.
If you push both tuberosities with the mother in a kneeling position resting forward on a surface or the floor, this can help relieve back pain and make a bit of space for a baby to turn. Squeezing the tuberosities in will make space at the pelvic inlet, holding them apart will increase space at the outlet.
Also see Balancing the pelvis for a lovely gentle technique.