The nonstress test (NST) was used as the primary tool in the management of 318 high-risk pregnancies. A simple and reliable method for interpreting the NST is obtained by dividing the total number of fetal heart rate accelerations associated with fetal movements by the total number of fetal movements. This is expressed as a percentage called the acceleration:fetal movement ratio. Fetuses at risk who were delivered within 7 days of the last NST form the basis of this report. The incidence of fetal distress and small-for-gestational-age infants was significantly higher (P<.05) in 47 fetuses with an acceleration:fetal movement ratio below 10% than in the group with a ratio over 10%. Also, perinatal mortality was more common in this group. The advantages and limitations of applying this quantitative method of interpreting the NST to the management of high-risk pregnancies are discussed.
(C) 1982 The American College of Obstetricians and Gynecologists