ATRIAL-NATRIURETIC-FACTOR CONCENTRATION IN NORMAL, GROWTH-RETARDED, ANEMIC, AND HYDROPIC FETUSES

OBJECTIVE: Our purpose was to establish a reference range with gestati on for plasma concentrations of atrial natriuretic factor in fetal blo od and to examine whether the concentration is altered in fetal anemia , acidemia, or hydrops. STUDY DESIGN: Atrial natriuretic factor was me asured in umbilical venous blood taken by cordocentesis from pregnanci es complicated by red blood cell isoimmunization (n = 17), intrauterin e growth retardation (n = 12), and hydrops fetalis (n = 20) and from c ontrols (n = 66). Additionally, maternal blood atrial natriuretic fact or concentration was measured in 40 uncomplicated pregnancies. RESULTS : In the control group detectable levels were found from 16 weeks onwa rd, and the fetal plasma atrial natriuretic factor concentration did n ot change with gestation. In anemic, acidemic, and hydropic fetuses th e concentration was higher than in controls. CONCLUSION: Fetuses are c apable of producing atrial natriuretic factor under physiologic condit ions, and the concentration is increased appropriately in pathologic s tates.