Protruding abdomen, increased back curve, pelvic changes, postural adaptations...these are just a few of the numerous  physiological and endocrinological changes that occur during pregnancy.  These  changes can result in a misaligned spine or joints.  When the pelvis is misaligned it may reduce the amount of room available for the developing baby.  A misaligned pelvis may also make it difficult for the baby to get into the best possible position for delivery.