Nonstress testing and contraction stress testing

A comparative study of a new cardiotocography analysis program

Cardiotocography (CTG) is a frequently used technique of fetal monitoring to evaluate the well being of the fetus during pregnancy and in labor. The surveillance technique depends on the analysis of characteristic fetal heart rate patterns and uterine contractions. Computerized analyses can mitigate the intra-observer and inter-observer variability of visual CTG recording explanation, decrease the examination time, and the need of additional tests for fetal health. Several studies also showed that the signal processing techniques could help to determine the fetal heart rate (FHR) patterns, but all of them were only suitable for physicians. Following the criteria and consensuses of National Institute of Child Health and Human Development in April 2008, we developed a LabVIEW based FHR and uterine contraction (UC) pattern analysis software. This software has great potential for home-care use. The signal processing methods utilized in this study are median filter and peak/valley detection method. The analysis performance was verified by nineteen pregnant women's data. The accuracy of FHR baseline, baseline variability, early deceleration, UC frequency and NST all reach 100%. The accuracy of acceleration frequency reaches 90%. The accuracy of late and variable decelerations reaches 95%.

Antenatal fetal assessment: contraction stress test, nonstress test, vibroacoustic stimulation, amniotic fluid volume, biophysical profile, and modified biophysical profile--an overview

Antenatal fetal assessment was introduced into the United States in the 1970s. The initial antepartum test, the oxytocin challenge test, later renamed as the contraction stress test, became the gold standard for fetal surveillance. Its labor intensive requirements and contraindications made it inapplicable to some high-risk pregnancies. Other testing schemes were developed subsequently, the nonstress test and its alternative, vibroacoustic stimulation, the semiquantitative assessment of amniotic fluid volume, the biophysical profile and its modified version, the modified biophysical profile. This article is a brief critical review of these testing methods and focuses on the following: (1) physiologic bases; (2) testing methodologies; (3) supportive evidence from randomized controlled and observational trials; and (4) areas needing further investigation.

Fetal activity following stimulation of the mother's abdomen, feet, and hands

Fetal activity during midgestation (M age=19.8 weeks) was studied in response to vibratory stimulation of the mother's abdomen (at the height of the fetal head), foot massage, hand massage, or control condition (no stimulation). Consistent with previous research conducted during midgestation, the fetuses of mothers who received two trials of 3-sec, 60-Hz vibratory stimulation did not show changes in movement. In contrast, the fetuses of mothers who received a 3-min foot massage showed greater movement than the control fetuses. However, stimulating the mother's hand (another highly innervated area) did not increase fetal activity. By late gestation (M age=35.4 weeks), vibratory stimulation resulted in increased fetal activity. These findings replicate previous research indicating that vibratory stimulation to the mother's abdomen does not elicit fetal activity until later in gestation. Furthermore, our findings indicate that stimulating the mothers' feet, but not the hands, can evoke fetal activity in midgestation.