Pregnancy tends to make your body a bit suppler. Tailor Sitting Kegel exercises. Only in Western cultures did lying flat on your back become popular for birth. In other cultures, upright positions have always been preferred, and for good reason. The baby is lined up correctly for passage down the birth canal, and gravity might help the process along.
Contractions are stronger, more efficient and less painful.
Sitting and squatting are beneficial because they open the pelvic outlet an extra quarter to half inch, allowing more room for the baby to descend. You will probably spend much of your time in labor walking and sitting. Squatting for a few minutes every so often will help open your pelvis. Sitting is easy enough, but squatting is tiring, so you should practice it frequently during pregnancy to strengthen the muscles needed. The wall slide exercise may be especially helpful.