RESUMEN
OBJECTIVE: To evaluate the shortening of the time of nonstress test (NST) by using transabdominal fetal stimulation with halogen light. STUDY DESIGN: Experimental research. MATERIAL AND METHOD: The authors enrolled 176 pregnant women between 32 and 42 weeks of gestation indicated for NST at the Division of Maternal Fetal Medicine, Siriraj Hospital, Mahidol University. They were randomly assigned to receive either NST (control) or halogen light stimulation test (LST). The stimulation was performed at the beginning of the test and repeated every 10 minutes until reassuring fetal heart rate (FHR) acceleration was achieved, or up to 3 times. All tracings were interpreted blindly by one investigator at the end of the tests. RESULTS: The mean (+/- SD) duration from starting the test to the first FHR acceleration was not significantly different between the control group and the LST group (5.6 +/- 7.2 and 5.4 +/- 5.2 minutes, respectively). The average testing time (+/- SD) to achieved reactivity was 10.5 +/- 8.8 minutes in the controls and 9.6 +/- 6.7 minutes in the LST group. This was not statistically different. The incidence of nonreactive tests was not significantly different between the LST and the controls (15.9% and 11.4%, respectively). Among the LST subjects, term fetuses and women with BMI < 27 kg/m2 required less time to reach reactivity, 2.4 and 2.3 minutes respectively. CONCLUSION: Transabdominal halogen light stimulation did not shorten the duration of NST in the presented population. However, the presented data suggests that the fetus at term could respond to visual stimulation, especially when the gestational age is more advanced.