Your baby plays a key role in labor progression. During delivery, the baby twists and turns to find the correct position to emerge out. It flexes its head to pass through the smallest birth canal. The still-soft plates of the babys skull will overlap one another on flexing so that it can come out quickly.
In some cases, the baby will not get the optimal birthing position. This scenario is an occiput posterior baby position. Here, the baby will face the mothers abdomen instead of her spine, and it cannot flex its head into the smallest possible diameter. The baby may get wedged behind or against the pelvic floor, leading to a longer push stage. If you have severe backache during labor, it is mostly because of this position.