Osteopathic manipulative medicine (OMM) is a complementary and alternative body-based treatment method in which the patient is evaluated and treated including the musculoskeletal system to improve physiologic functioning and remove impediments to optimal health and functioning. During pregnancy, a woman's body is challenged by significant and extensive physiological and biomechanical changes that impact all her body systems and all aspects of her life. Many of these changes are reflected in her musculoskeletal system, and are able to be affected by OMM. This proposal will investigate the efficacy and hypothesized physiological mechanisms by which OMM affects selected conditions related to pregnancy, labor and delivery by conducting three studies over five years. Study One will address the efficacy of adjunctive OMM therapy during 3rd trimester of pregnancy in improving several clinical outcomes whereas Studies Two and Three will address potential physiological and biomechanical mechanisms that may contribute to these clinical benefits. Study hypotheses and aims include: Study One Hypothesis OMM improves selected clinical outcomes in pregnancy. Aim: To determine if OMM can decrease low back pain in the pre and post-partum period Aim: To determine if OMM can improve functional status in the pre and post-partum period Aim: To determine if OMM can decrease the incidence of meconium-stained amniotic fluid in labor and delivery as an index of fetal stress Study Two Hypothesis Physiological changes related to improved autonomic and peripheral hemodynamic regulation are, in part, responsible for the hypothesized clinical effects of OMM in Study One. Aim: To examine how OMM affects autonomic balance during pregnancy, Aim: To determine how OMM impacts lower extremity edema in the third trimester of pregnancy Study Three Hypothesis Biomechanical changes related to improved gait are, in part, responsible for the hypothesized clinical effects of OMM in Study One. Aim: To evaluate functional and biomechanical changes in gait in the third trimester of pregnancy, and how OMM may affect gait. These 3 studies will use a placebo-controlled, randomized, blinded design to test the impact of the OMM intervention on the selected outcomes. If OMM is found to be efficacious in the treatment of the selected outcomes of pregnancy, labor, and delivery, it should be considered a complementary part of routine prenatal care as a way to improve maternal-fetal health.