Antepartum nonstress fetal heart rate monitoring: systematic analysis of baseline patterns and decelerations as an adjunct to reactivity in the prediction of fetal risks.

A total of 1552 antepartum nonstress tests performed during the week before delivery are analyzed with respect to both reactivity and the presence of pathologic baseline patterns (tachycardia, bradycardia, diminished beat-to-beat variability) or decelerations. Correlation with mode of delivery and condition of the newborn infant shows that, irrespective of nonstress test reactivity, the presence of baseline anomalies and/or decelerations is associated with significantly increased perinatal morbidity and mortality. Nonstress test analysis, if systematic, that is, not restricted to reactivity alone, makes it possible to better detect fetuses at high perinatal risk, in which case closer surveillance would be indicated.