Fetal Heart Rate Reactivity Research Articles

Intravaginal misoprostol vs. expectant management in premature rupture of membranes with low Bishop scores at term

Objectives: To evaluate the efficacy of vaginal misoprostol for cervical ripening and labor induction in premature rupture of membranes (PROM) cases with low Bishop scores at term. Methods: Sixty-two PROM cases who fulfilled the criteria of 36 weeks of completed gestation, not in active labor, singleton pregnancy with vertex presentation, normal fetal heart rate reactivity, amniotic fluid index >5 cm and Bishop score <5, consented to participate in the study. Thirty-one of the cases were included in study group and a 50-μg misoprostol tablet was placed in the posterior vaginal fornix. Another 31 cases were included in control group and managed expectantly. Treatment success was defined as an interval from membrane rupture to delivery of <24 h. Results: The mean admittance–delivery interval was significantly shorter in the study group (8.68±4.40 h) compared with the control group (26.22±18.98 h, P=0.001) and the mean interval from membrane rupture to delivery were also significantly shorter in the study group (19.37±7.20 h) than the control group (33.05±20.85 h, P=0.001). Oxytocin necessity was significantly lower in the study group than the control group (45.2% vs. 100%, P=0.00051). Tachysystole occurred more frequently in the study group (8 cases, 25.8% vs. 2 cases, 6.5%, P=0.038). There were no difference between two groups with regard to birth weights, 1- and 5-min Apgar scores and the need for neonatal intensive care unit. Conclusions: It is effective, safe and economic to use misoprostol vaginally in PROM cases with low Bishop scores at term.

The effect of cigarette smoking on fetal heart rate characteristics

OBJECTIVE: To evaluate the effect of repeated cigarette smoking on fetal heart rate (FHR) characteristics. METHODS: Fifteen chronic smokers who were between 28 and 36 weeks’ gestation were evaluated during an 8-hour smoking session. Baseline FHR and reactivity were evaluated before an initial cigarette and 4 hours later (after the fourth cigarette), when the effects of smoking on FHR were expected to be maximal. Plasma nicotine was measured at baseline and repeated at times of fetal monitoring. RESULTS: Subjects smoked a mean ± standard deviation of 22 ± 6 cigarettes per day. They abstained from smoking for 9.2 ± 3.2 hours before evaluation. The initial baseline FHR was 134 ± 9 beats per minute versus 135 ± 11 beats per minute after the fourth cigarette ( P = .17). Plasma nicotine increased from 2.6 ± 5.6 ng/mL to 24 ± 9.9 ng/mL after the fourth cigarette ( P < .001). The initial nonstress test was reactive in 12 of 15 (80%) of the fetuses. After the fourth cigarette, only four of 15 (27%) of the nonstress tests were reactive. A majority of tracings (eight of 15) were initially reactive before smoking and became nonreactive after smoking. Some tracings remained nonreactive (three of 15), and some tracings remained reactive (four of 15) at both assessments. None of the tracings that were initially nonreactive became reactive. The change in reactivity was significant ( P = .013). CONCLUSION: Acute, repeated smoking decreases FHR reactivity.

The relationship of fetal eye movements to non-stress test results

Objective: This study was designed to correlate ultrasound-observed fetal eye movements with fetal heart rate reactivity to determine its potential role in fetuses with persistent non-reactivity.Methods: A total of 104 non-stress tests (NSTs) were evaluated in 62 patients referred for fetal surveillance for standard antepartum indications. Ultrasound-observed eye movements, assessed duringportions of these NSTs, were categorized as negative (0), intermittent (1-5/min), or rapid (≥ 6/min).Results: Of the NSTs, 97 were reactive and seven were non-reactive. All studied fetuseswere apparently healthy, as the seven patients with persistently non-reactive NSTs had biophysical profile scores of 8/10. During the NSTs, 120 reactive portions and 81 non-reactive portions were evaluatedfor ultrasound-observed eye movements. During reactive portions, eye movements were negative 19% of the time, intermittent 24% of the time and rapid 56% of the time. During non-reactive portions, eye movementswere negative 84% of the time, intermittent 7.8% of the time and rapid 7.8% of the time. All fetuses demonstrating eye movements during non-reactive periods became reactive shortly thereafter, and all ofthe seven persistently non-reactive fetuses displayed negative ultrasound-observed eye movements throughout the entire observation period.Conclusions: Healthy fetuses display a strong relationshipbetween non-reactive heart rate tracings and absent or diminished eye movements, consistent with quiet sleep. Conversely, reactive periods are associated with a high incidence of rapid eye movement. Furtherstudy is needed in fetuses documented to be hypoxic.

The Effects of Maternal Depression on Fetal Heart Rate Response to Vibroacoustic Stimulation

To better understand the effects of untreated maternal depression on the fetus, this study examined fetal heart rate (FHR) and FHR reactivity to vibroacoustic stimulation in pregnant women with untreated depression. The 20 participants were 32- to 36-week pregnant women divided into groups with depression (N = 10) and without depression (N = 10) based on the Beck Depression Inventory (BDI; Beck, 1977; Beck & Steer, 1987). Participants were attached to a fetal heart monitor, and 10 min of baseline FHR were recorded. A vibroacoustic stimulus (VAS) was presented, and an additional 10 min of FHR were recorded. Fetuses of mothers with depression had an elevated baseline FHR and a 3.5-fold delay in return to baseline FHR after VAS presentation. Additionally, mothers with depression had significantly higher anxiety levels and took fewer prenatal vitamins during pregnancy. Delayed habituation of FHR in the fetuses of mothers with depression may be due to alterations in the internal hormonal environment and could have implications for postnatal information processing.

The Effects of Maternal Depression on Fetal Heart Rate Response to Vibroacoustic Stimulation

To better understand the effects of untreated maternal depression on the fetus, this study examined fetal heart rate (FHR) and FHR reactivity to vibroacoustic stimulation in pregnant women with untreated depression. The 20 participants were 32- to 36-week pregnant women divided into groups with depression (N = 10) and without depression (N = 10) based on the Beck Depression Inventory (BDI; Beck, 1977; Beck & Steer, 1987). Participants were attached to a fetal heart monitor, and 10 min of baseline FHR were recorded. A vibroacoustic stimulus (VAS) was presented, and an additional 10 min of FHR were recorded. Fetuses of mothers with depression had an elevated baseline FHR and a 3.5-fold delay in return to baseline FHR after VAS presentation. Additionally, mothers with depression had significantly higher anxiety levels and took fewer prenatal vitamins during pregnancy. Delayed habituation of FHR in the fetuses of mothers with depression may be due to alterations in the internal hormonal environment and could have implications for postnatal information processing.

The biophysical profile in multiple pregnancy

The high risk attributed to multiples calls for close observation during pregnancy. Based on adequate predictions in singletons, it was expected that the biophysical profile (reactive fetal heart rate pattern on non-stress test, presence of fetal breathing and body movements, documentation of normal fetal tone and adequate amount of amniotic fluid) could be used in multiples as well. However, the paucity of studies could not demonstrate an equivalent predictive capacity in multiple pregnancies.

The biophysical profile in multiple pregnancy

ABSTRACTThe high risk attributed to multiples calls for close observation during pregnancy. Based on adequate predictions in singletons, it was expected that the biophysical profile (reactive fetal heart rate pattern on non-stress test, presence of fetal breathing and body movements, documentation of normal fetal tone and adequate amount of amniotic fluid) could be used in multiples as well. However, the paucity of studies could not demonstrate an equivalent predictive capacity in multiple pregnancies.

Corticotrophin-releasing hormone and fetal responses in human pregnancy.

During human pregnancy, maternal and fetal compartments of the human placenta produce and release corticotrophic-releasing hormone (CRH). Elevations of placental CRH are associated with decreased gestational length (including preterm delivery). The effects of elevated placental CRH on human fetal neurological development are not known. Pregnant women in the 31st and 32nd week of gestation consented to procedures for collection of blood and measurement of fetal heart rate (FHR) in response to a series of 40 vibro-acoustic stimuli (VAS). Measures of habituation and dishabituation were calculated from the FHR. All subjects were followed to delivery. Fetuses (N = 33) of women with highly elevated CRH were least responsive (p < .03) to stimulation after presentation of a novel (dishabituating) stimulus with control for parity, fetal gender, medical (antepartum) risk, and gestational length at term. In a larger sample (N = 156) a polynomial model predicted the pattern of FHR reactivity for the first 15 trials. Placental CRH concentration significantly predicted FHR reactivity after controlling for the effects of trial number, baseline FHR, inter-trial interval, and presence of uterine contractions. Increased maternal CRH levels were significantly related to the length of gestation after controlling for the effects of fetal gender, parity, and medical risk (p = .05). The relationship between length of gestation and FHR was not significant suggesting separate actions of CRH on these events. Elevated placental CRH appears to accelerate certain developmental events (gestational length) and may influence the fetal nervous system. The impaired fetal responses to novelty and increased arousal observed in this study suggest that neurological systems may be targets for placental CRH during sensitive developmental periods.

Fetal heart rate characteristics at 25 to 28 weeks' gestation.

The objective of this article is to define normative fetal heart rate (FHR) tracing characteristics between 25-28 weeks' gestation in a low-risk population with normal pregnancy outcomes and to determine which criteria best determine FHR reactivity. Continuous FHR tracings were reviewed from 188 low-risk women participating in a trial of the Mammary Stimulation Test (MST) at 25-28 weeks' gestation. A reactive tracing required the presence of > or =two accelerations in 20 min. Different acceleration criteria were evaluated based upon the width of the acceleration (short vs. long) and the amplitude of the acceleration (10 vs. 15 bpm). Seventy-one percent of the FHR tracings were reactive using the higher amplitude (15 bpm), short criteria. This number increased significantly to 92% when the lower amplitude (10 bpm), short criteria were used (p <0.01). As gestational age advanced, there was a trend toward increased reactivity irrespective of which criteria were used, but these differences were not significant. Reducing the acceleration amplitude criteria to 10 bpm in preterm pregnancies will maximize the number of reactive nonstress tests. This is advantageous because it would improve test specificity and decrease the false-positive rate. Our findings need to be prospectively validated in a high-risk population.

Effects of 4 hours magnesium sulfate infusion on fetal heart rate variability and reactivity in a goat model.

Effects of magnesium sulfate were investigated on fetal heart rate (FHR) baseline, variability, and reactivity in goats. Six chronically catheterized fetuses of Japanese Saanen goat at 125 to 130 days' gestation (term = 147 days) were used. Magnesium sulfate was directly infused to the fetuses. Short-term variability and long-term variability were obtained according to Huey et al. The baseline, reactivity, short-term variability and long-term variability of the FHR were compared between those receiving magnesium sulfate infusions and those receiving vehicle infusions without magnesium sulfate for 4 hr. Two-way analysis of variance (ANOVA) and Duncan's multiple range test was applied for statistical significance. Four hours magnesium sulfate infusion significantly increased fetal plasma concentration of magnesium from 2.4-6.6 mg/dL, without significant changes in fetal respiratory gases and pH values. The baseline FHR was significantly decreased by magnesium infusion compared with that receiving vehicle infusion. The incidence of acceleration, short-term variability, and long-term variability during the fourth hour of magnesium infusion was also significantly decreased compared to a controlled infusion. The time spent by high amplitude phase of short-term variability and that of long-term variability were also significantly reduced. Significant correlation was obtained between the magnesium concentration and incidence of acceleration at fourth hour of magnesium infusion. Four hours infusion of magnesium sulfate significantly decreases baseline FHR, short-term variability, long-term variability, and reactivity in fetal goats at 0.85 gestation.

Effects of transdermal nicotine or smoking on nicotine concentrations and maternal-fetal hemodynamics

To compare nicotine concentrations and fetal middle cerebral artery resistance indices (RIs) during 21-mg transdermal nicotine use with these values during maternal smoking. In this randomized, crossover study, participants smoked approximately 20 cigarettes daily and were between 24 and 36 weeks' gestation. Subjects were randomized to transdermal nicotine or to smoking ad libitum for 8 hours. One week later, they crossed over to the other condition. Maternal plasma nicotine concentrations and hemodynamic measurements were obtained before and after the onset of smoking or patch placement. Area under the plasma nicotine concentration-time curve during patch use was similar to continued smoking (93 versus 89 ng-hour/mL, respectively) (P = .77). The mean (standard error [SE] change in the middle cerebral artery RI from baseline to 4 hours later was similar during patch use and smoking: -.002 (0.008) versus -.02 (0.015), respectively (P = .3). The study had greater than 80% power to detect a 25% difference in nicotine concentrations and a change of 2 standard deviations in the middle cerebral artery RI between conditions. An unexpected finding was that of a loss of fetal heart rate (FHR) reactivity in 5/8 tracings after patch placement versus 1/6 tracings after smoking (P = .12). The baseline FHR increased by a mean (SE) of 8 (4) beats per minute with loss of reactivity in the patch condition, compared with a decrease of 3 (3) beats per minute without loss of reactivity (P = .05). Eight-hour use of 21-mg transdermal nicotine yields nicotine concentrations and middle cerebral artery RIs similar to those produced by hourly smoking in pregnant smokers.

Semi-Fowler’s Positioning, Lateral Tilts, and Their Effects on Nonstress Tests

To determine whether a lateral tilt for women in semi-Fowler's position for antepartum nonstress tests (NSTs) (a) promotes NST reactivity or (b) shortens testing time required to obtain a reactive tracing. An antepartum fetal assessment unit of a tertiary care facility in eastern Canada. In this prospective, randomized study, a computer analysis of the NSTs was used to obtain an objective, standardized interpretation of fetal heart rate reactivity. Participants were randomly assigned to two experimental groups using semi-Fowler's position with a 45-degree tilt to either the left or right, or to a control group using semi-Fowler's position with no lateral tilt. A convenience sample of 823 nonstress tests was obtained from women with singleton pregnancies, intact amniotic membranes, and gestations between 32 and 42 weeks. The final sample available for analysis totaled 738 nonstress tests from 573 pregnancies. Percentage of reactive nonstress tests and the number of minutes required for tests to be reactive. The rate of reactive NSTs and the time to achieve a reactive NST did not differ statistically for any of the three study groups. Likewise, NST outcomes were similar when the left-tilt group was compared with the right-tilt group. Although no significant differences were found between study groups, less than 2% of the women in the control group (semi-Fowler's position without a lateral tilt) experienced symptoms consistent with supine hypotensive syndrome. No statistically or clinically significant differences were found in nonstress tests between the three groups. Lateral tilting did not shorten test time. Results do suggest that hemodynamic changes can occur in 3rd trimester women who are in semi-Fowler's position without a lateral tilt. Lateral tilting of gravidas in semi-Fowler's position during nonstress testing is thus supported to avoid hypotensive symptoms.

Nucleated red blood cells: An update on the marker for fetal asphyxia

OBJECTIVE: Our goal was to update our experience with nucleated red blood cells as a marker for fetal asphyxia and to determine whether a relationship exists between the presence of nucleated red blood cells and long-term neurologic impairment. STUDY DESIGN: Nucleated red blood cell data from 153 singleton term neurologically impaired neonates were compared with cord blood nucleated red blood cells of 83 term nonasphyxiated newborns. Newborns with anemia, intrauterine growth restriction, and maternal diabetes were excluded. The group of neurologically impaired neonates was separated into the following subgroups: group I, persistent nonreactive fetal heart rate pattern from admission to delivery (n = 69); group II, reactive fetal heart rate on admission followed by tachycardia with decelerations and absent variability (n = 47); group III, reactive fetal heart rate on admission followed by an acute prolonged deceleration (n = 37). The first and highest nucleated red blood cell value and the time of nucleated red blood cell disappearance were assessed. RESULTS: The mean number of initial nucleated red blood cells was significantly higher in the group of neurologically impaired neonates (30.3 ± 77.5, range 0 to 732 per 100 white blood cells) than in the control group (3.4 ± 3.0, range 0 to 12 per 100 white blood cells) (p < 0.000001). When the group of neurologically impaired neonates was separated on the basis of timing of the neurologic impairment, distinct nucleated red blood cell patterns were observed. Significant differences were obtained between each of the three groups of neurologically impaired neonates and the normal group, with respect to initial nucleated red blood cells (group I, 48.6 ± 106.9; group II, 11.4 ± 9.8; group III, 12.6 ± 13.4; p≤ 0.000002). Maximum nucleated red blood cell values were higher in group I (mean 51.5 ± 108.9) than in groups II and III combined (mean 12.7 ± 11.9) (p = 0.0005). Group I also had a longer clearance time (119 ± 123 hours) than groups II and III combined (mean 59 ± 64 hours) (p < 0.001). CONCLUSION: Our ongoing study indicates that nucleated red blood cells identify the presence of fetal asphyxia. When fetal asphyxia is present, distinct nucleated red blood cell patterns are observed that relate to the timing of fetal injury. In general, intrapartum injuries are associated with lower nucleated red blood cell values. Thus our data continue to support the concept that nucleated red blood cell levels may assist in determining the timing of fetal neurologic injury. (Am J Obstet Gynecol 1996;175:843-6.)

Nucleated red blood cells: A marker for fetal asphyxia?

OBJECTIVE: Our purpose was to determine whether a relationship exists between the presence of nucleated red blood cells, hypoxic ischemic encephalopathy, and long-term neonatal neurologic impairment. STUDY DESIGN: Nucleated red blood cell data from 46 singleton term neurologically impaired neonatee were compared with cord blood nucleated red blood cells of 83 term nonasphyxiated newborns. The neurologically impaired neonates group was also separated as follows: nonreactive, nonreactive fetal heart rate from admission to delivery; tachycardia, reactive fetal heart rate on admission followed by tachycardia with decelerations; rupture, uterine rupture. The first and highest nucleated red blood cells value and the time to nucleated red blood cells disappearance were assessed. RESULTS: The neurologically impaired neonates group exhibited a significantly higher number of nucleated red blood cells per 100 white blood cells (34.5 ± 68) than did the control group (3.4 ± 3.0) ( p < 0.00001). When the neurologically impaired neonates are separated as to the basis for the neurologic impairment, distinct nucleated red blood cell patterns were observed. Overall, the nonreactive group exhibited the highest mean nucleated red blood cell (51.4 ± 87.5) cound and the longest clearance times (236 ± 166 hours). CONCLUSION: In this limited population, nucleated red blood cell data appear to aid in identifying the presence of fetal asphyxia. When asphyxia was present, distinct nucleated red blood cells patterns were identified that were in keeping with the observed basis for the fetal injury. In general, the closer the birth was to the asphyxial event, the lower was the number of nucleated red blood cells. Thus our data suggest that cord blood nucleated red blood cells could assist in the timing of fetal neurologic injury.

Antepartum surveillance in diabetic pregnancies: Predictors of fetal distress in labor

OBJECTIVE: Our purpose was to evaluate an antepartum testing program based on twice-weekly nonstress testing and amniotic fluid evaluation in pregnancies complicated by diabetes mellitus and to weight the test components in the prediction of fetal distress requiring cesarean delivery. STUDY DESIGN: During the 4-year period of 1987 through 1990, 2134 women with pregnancies complicated by diabetes underwent antepartum testing. Of these 1501 women (class A 1, n = 505; A 2-diet, n = 305; A 2-insulin, n = 580; B, n = 71; C to D, n = 29; R to F, n = 11) were delivered within 4 days of their last test. Categoric analysis of data was performed according to diabetic class, fetal heart rate results, and the presence of decreased, normal, or increased amniotic fluid assessment. A univariate logistical regression was first conducted with cesarean delivery for fetal distress as outcome variable by use of the following variables: fetal weight and sex, diabetic class, gestational age at delivery, presence of additional indications for antepartum testing, largest vertical pocket, amniotic fluid index (summation of the four quadrants of the largest vertical pocket), nonstress test reactivity (two accelerations of ≥ 15 beats/min of 15 seconds' duration), presence of decelerations (≥ 15 beats/min for 15 seconds) during the nonstress test, and the interactions of the nonstress test with deceleration, largest vertical pocket, and amniotic fluid index. Multivariate analysis was then applied to predict the best model. RESULTS: No stillbirths occurred within 4 days of the last antepartum test. However, the corrected stillbirth rate of the entire tested population was 1.4 per 1000. Eighty-five women required cesarean delivery for fetal distress. The factors most predictive of cesarean delivery for fetal distress ( p < 0.05, odds ratio and 95% confidence interval) were a deceleration (3.60, 2.14 to 6.06), nonreactive nonstress test (2.68, 1.60 to 4.49), and the interaction of both a nonreactive nonstress test and decelerations (5.63, 2.67 to 11.9). Amniotic fluid assessment by largest vertical pocket or amniotic fluid index were not statistically significant. The multivariate analysis selected the interaction of nonstress test and deceleration as the best significant predictor for cesarean delivery for fetal distress. CONCLUSION: An antepartum fetal surveillance program using twice-weekly nonstress test and fluid index assessment in pregnancies complicated by diabetes was successful in preventing stillbirth. The absence of fetal heart rate reactivity and the presence of decelerations were predictive of the diagnosis of fetal distress in labor requiring cesarean delivery. Ultrasonographic assessment of amniotic fluid volume was not a significant predictor of fetal distress in labor in the diabetic pregnancy.

Scalp blood lactate: a new test strip method for monitoring fetal wellbeing in labour.

To determine fetal scalp blood lactate with a new test strip method in parturients with normal and abnormal cardiotocograms during labour and to describe the relation to maternal lactate, fetal scalp blood pH, cord artery lactate and acid-base balance. Labour wards at the University Hospitals of Huddinge and Lund and at the County Hospital of Ostersund, Sweden. Fetal scalp blood was sampled for lactate (n = 269) and pH (n = 285) determination in 177 parturients with abnormal intrapartum CTG. Lactate and pH were also analysed in a group of 64 women with normal pregnancies and with a reactive fetal heart rate tracing prior to sampling of fetal scalp blood. At fetal blood sampling lactate was also determined in maternal capillary blood, while at birth lactate and acid-base balance in cord artery blood was performed in almost all cases. Medians and percentiles (lactate and acid-base balance). Correlation between fetal scalp blood lactate (dependent) and scalp blood pH, cord artery blood lactate and acid-base parameters and labour time prior to fetal blood sampling. In the group with abnormal cardiotocograms, fetal scalp and umbilical artery blood lactate and acid-base parameters differed significantly from the same parameters in the normal group. The fetal-maternal lactate gradient changed from negative in the normal group to positive in the fetal distress group. Multiple regression analysis, with scalp lactate as the dependent parameter, revealed a significant correlation with fetal scalp blood pH (P < 0.001) and umbilical artery lactate (P < 0.01). Intrapartum scalp blood lactate was significantly correlated with pH and cord artery lactate. The results indicate that increased lactate levels in fetal blood sampling describes fetal lactacidosis. The new disposable test strip requiring only 5 microliters of blood for lactate determination may be better than traditional methods for monitoring fetal wellbeing in labour.

Comparison of the effects of meperidine and nalbuphine on intrapartum fetal heart rate tracings

To examine the effects of meperidine and nalbuphine on intrapartum fetal heart rate (FHR) tracings using computer analysis. We studied 28 women with uncomplicated pregnancies in early labor at term with reactive FHR tracings. The women were randomized to receive either meperidine 50 mg or nalbuphine 10 mg intravenously on request. One-hour FHR recordings were obtained before and immediately after administration of the medications. There were no significant differences in the FHR characteristics of the two groups during the pre-treatment period. Nalbuphine significantly decreased the number of accelerations of 10 beats per minute (17 versus 4, P = .003) and 15 beats per minute (10 versus 1.5, P = .001), time spent in episodes of high variation (35.5 versus 10 minutes, P = .004), long-term variation (47 versus 29.8 milliseconds, P = .002), and short-term variation (8.4 versus 6.4 milliseconds, P = .03). Meperidine had no significant effect on any FHR characteristic. In the early intrapartum period of normal term pregnancies and at commonly used dosages, nalbuphine had a significant effect on FHR tracings, whereas meperidine had no effect, as determined by computer analysis.

Fetal biophysical profile and vibratory acoustic stimulation in high-risk pregnancies

To determine the influence of the non-stress test (NST) on the efficiency of the fetal biophysical profile (FBP) and to test the clinical usefulness of the FBP and its combination with vibratory acoustic stimulation (VAS) in managing high-risk pregnancies. One hundred twenty fetuses of preeclamptic patients were included in a prospective study. Five standard variables of the FBP were observed ultrasonically following NST. In cases of non-reactive NST, external VAS was applied and the FBP score calculated and compared with the FBP score before VAS. Of 120 calculated FBPs, 102 (85%) had normal profile scores before VAS and 104 (86.7%) after VAS. No statistically significant difference was found. The sensitivity, specificity, and positive and negative predictive values of the FBP score in predicting poor perinatal outcome were 94.7%, 94.4%, 75% and 99%, respectively. VAS produced a high conversion (58.8%) of non-reactive NST to reactive fetal heart rate pattern. The false-negative rate of the FBP score was 9.8 per 1000, which did not increase after VAS. The efficiency of the FBP score was not significantly improved by VAS, although a high conversion of non-reactive to reactive NST was produced. The FBP with its three 'acute biophysical variables' was found to be an accurate method of antepartum assessment even without an NST. The low incidence of perinatal complications among patients with normal FBP scores, permits the conservative management of preterm high-risk pregnancies.

Antenatal bleeding and fetal heart rate.

Objective of the paper was to determine the fetal heart rate (FHR) changes that occur in preterm fetuses whose mothers have suffered antepartum bleeding, versus uncomplicated controls. Over a 12-year span, 91 patients with significant antenatal bleeding (bleeding requiring inhospital observation) were examined and compared to 75 controls with uncomplicated normal pregnancies. None of the women were in labor and all were evaluated at 25-37 weeks' gestation. Excluded were: patients with any other complication (i.e., premature rupture of membranes, intrauterine growth retardation, diabetes, hypertension, collagen vascular disease, postuterine surgery, substance abuse and twins). Analysis of the FHR tracings included baseline heart rate, long-term FHR variability, and number and amplitude of FHR accelerations in 20-min segments. There was no difference in baseline heart rate in the preterm fetuses of pregnancies complicated by antepartum bleeding versus controls. However, the parameters associated with FHR reactivity (number of accelerations in 20 min, and amplitude of accelerations) were higher to a statistically significant degree in fetuses of pregnancies complicated by antenatal bleeding than in controls. Fetuses of mothers suffering antenatal bleeding exhibited significant higher rates of reactive FHR patterns at earlier gestational ages than did controls. In conclusion, there is a significant increase in FHR reactivity in pregnancies in which significant antenatal bleeding occurs, suggesting a probable acceleration in fetal central nervous system maturation in these fetuses.

Blunted Fetal Response to Vibroacoustic Stimulation Associated with Maternal Intravenous Magnesium Sulfate Therapy

Maternal intravenous magnesium sulfate (MgSO4) therapy has been associated with decreased fetal heart rate (FHR) variability and reactivity, resulting in an increased incidence of nonreactive nonstress tests, frequently requiring further assessment of fetal well-being. This study was designed to assess fetal response to vibroacoustic stimulation in association with maternal intravenous MgSO4 therapy. Five gravidas with singleton gestations with normal fetal anatomy, intact membranes, and normal amniotic fluid volume at 31 weeks or more presenting with preterm labor were included. Vibroacoustic stimulation was performed prior to and during subsequent intravenous MgSO4 therapy so that each fetus served as its own control. Ultrasound was applied during vibroacoustic stimulation to assess fetal movement response. Response to vibroacoustic stimulation was considered normal if a FHR acceleration of at least 15 beats/min for at least 15 seconds occurred within 15 seconds after the stimulation with prolonged fetal movements. Maternal serum magnesium levels were obtained prior to each stimulation. All fetal responses prior to treatment were normal. All subsequent fetal responses in association with intravenous MgSO4 were abnormal, consisting of blunted FHR accelerations of 10 to 15 beats/min and ranging between 10 and 15 seconds in duration associated with brief limited fetal movements. Mean maternal serum magnesium levels (+/- standard error) during vibroacoustic stimulation, prior to and following intravenous MgSO4, were 1.4 +/- 0.1 and 5.2 +/- 0.4 mEq/L, respectively (P = 0.008). All 5-minute Apgar scores were 8 or higher. This occurrence may reflect an effect of magnesium on the fetus as either a central nervous system depressant or alternatively as a peripheral neuromuscular relaxant.(ABSTRACT TRUNCATED AT 250 WORDS)