Effects of twins: maternal, fetal, and labor.

During pregnancy, many physical changes, physiological alterations, and biochemical values have been well established. Twins bring differences to many of these normal pregnancy observations. The mother has exaggerations of normal pregnancy changes. The twin fetuses often respond differently from singletons, and labor in twins presents its own unique problems. This article examines many of the adaptations in a twin pregnancy, assuming knowledge of the normal pregnancy.