Previous studies have reported associations between maternal stress during pregnancy and obstetric outcomes as well as fetal development and neonatal adaptation. These findings highlight the importance of identifying pregnant women who experience severe stress and the need for interventions that commence early in pregnancy. The aim of this study was to review studies that investigated the effects of relaxation techniques during pregnancy, including maternal, fetal, and neonatal outcomes. In addition, studies examining maternal endocrine and physiological alterations were reviewed. PubMed was searched using the following key words: maternal well-being, maternal stress, relaxation techniques, pregnancy, fetal neurobehavior, fetal heart rate, neonatal adaptation, and neonatal behavior. (1) Relaxation had a positive impact on women's emotional state. (2) Pregnancy outcomes improved with fewer admissions to the hospital, fewer obstetric complications, longer gestation, reduction of caesarean sections, and fewer postpartum complications. (3) Fetal heart rate and fetal motor activity were reduced as a result of relaxation and therefore interpreted as improved result. (4) Higher-birth-weight and improved performance on the Neonatal Behavioral Assessment Scale was related to relaxation. (5) Relaxation training was associated with reductions in maternal physiological and endocrine measures. Relaxation during pregnancy is associated with salutogenic effects that include regulation of emotional states and physiology. Relaxation is also associated with positive effects both on fetal behavior and on obstetric and neonatal outcomes. Identifying pregnant women at risk and instituting treatment early in pregnancy could improve obstetric and developmental outcomes for both the mother and her fetus.