In prenatal yoga, it’s best to avoid deep, closed twists that put pressure on the abdomen, and therefore, on the baby.  But a gentle seated twist can help to open hips and release tension in the spine, and help you to find a neutral pelvis, anchored through your sitz bones.  With baby facing mostly forward, and a focus on lengthening through the spine and side ribs, this twist is a great stretch for the mid and upper back.