Factors that increase reactivity during fetal nonstress testing.

Purpose Of Review: The most common method of antepartum fetal surveillance is the nonstress test (NST). Although it has satisfactory false-negative rates, dubious nonreactive results may challenge the physician. Any method or factor increasing the reactive NST results or shortening the time to attain a reactive test may be considerably useful.

Recent Findings: Most of the studies have found no effect of maternal glucose administration on fetal heart rate and fetal activity, specificity of NST, time to reactivity and percentage of reactive NST results when compared with the control group. Maternal intake of 70% cocoa or caffeine had stimulating action on the fetal reactivity, and this effect on the fetal heart rate was more marked with high concentrations of cocoa (80%). Studies on maternal positioning during NST had equivocal results. Fetal manipulation has no impact on the NST reactivity. Vibroacoustic and halogen light stimulation may be associated with a reduction in time to reactivity.

Summary: These methods may increase the reactivity during a NST and may facilitate the antenatal fetal surveillance.