It is generally recommended that for easy delivery of your baby you adopt a position in which your tailbone can “untuck” and allow the widest space possible between your pubic bones and tailbone. Here is an amazing article that explains why this position is so great, not just for birth but for general pelvic floor health:
The optimum position is a squat in which your tailbone sticks out behind you but this can be an unusual movement and/or uncomfortable to sustain so please see below for some other ideas.
NB: the third picture here shows a squatting position that is NOT suitable for birth – see how the tailbone is tucked right under (which would block the baby’s way). A slightly higher squat will make it easier for baby but is harder for your legs to sustain! See below for supported versions.
Supported Squats with a Partner
Kneeling with a ball/beanbag/bed for support
Kneeling with a partner for support
Most hospital settings now encourage “active” labours but none-the-less may ask you to lie on a bed for monitoring and examinations. You can request extra long wires so you can be monitored while moving around and you can also lie on your side whilst on the bed for delivery to allow full movement of the pelvis.