Antepartum bed-rest treatment is based on assumptions that it is both effective and safe for mother and fetus. However, research indicates, that bed-rest treatment is ineffective for preventing preterm birth and fetal growth restriction, and for increasing gestational age at birth and infant birthweight. Studies of women treated with pregnancy bed-rest identify numerous side effects, including muscle atrophy, bone loss, weight loss, decreased infant birthweight in singleton gestations and gestational age at birth, and psychosocial problems. Studies conducted by aerospace scientists who have used bed rest as a model for the study of weightlessness in space using nonpregnant individuals report similar results. Antepartum bed-rest treatment should be discontinued until evidence of effectiveness is found.