Changes of pulsatility index from fetal vessels preceding the onset of late decelerations in growth-retarded fetuses.

Thirty-six growth-retarded fetuses selected from a population of 214 cases were studied by Doppler ultrasonography at weekly intervals for at least 4 weeks between the diagnosis of Doppler abnormalities suggestive of the existence of the brain-sparing effect (ie, ratio between umbilical artery and middle cerebral artery pulsatility indexes [PIs] above the 95th percentile of our reference limits) to the onset of antepartum late fetal heart rate (FHR) decelerations. Recordings were made from the umbilical artery, descending aorta, renal artery, internal carotid artery, and middle cerebral artery and the PIs were calculated. Statistically significant changes in PI occurred in all the vessels studied. However, different trends were found when the modifications in cerebral vessels were compared with those in fetal peripheral vascular beds and in the umbilical artery. In cerebral arteries, a nadir of vasodilatation was reached 2 weeks before the onset of antepartum late FHR decelerations, whereas significant changes in the peripheral and umbilical vessels occurred close to the onset of abnormal FHR patterns. This study demonstrates that despite a brain-sparing effect, there are further Doppler-detectable modifications in fetal circulation that differ between the cerebral and peripheral vascular beds.     

Computer analysis of maternal–fetal heart rate recordings during labor in relation with maternal–fetal attachment and prediction of newborn acidemia

Objective: To assess combined maternal (MHR) and fetal heart rate (FHR) recordings during labor, in relation with maternal–fetal attachment and prediction of newborn acidemia.

Study design: Fifty-nine simultaneous MHR and FHR recordings were acquired in the final minutes of labor. Computer analysis followed the FIGO guidelines with estimation of MHR and FHR baselines, accelerations, decelerations, short- (STV) and long-term variabilities. MHR and FHR characteristics, their differences and correlations were assessed in relation to labor progression and to newborn umbilical artery blood (UAB) pH lower than 7.15 and 7.20. To assess prediction of acidemia, areas under ROC curves (auROC) were calculated.

Results: Progression of labor was associated with a significant increase in MHR accelerations and FHR decelerations both in the non-acidemic and acidemic fetuses (p?<?0.01). At the same time there was an increase in MHR–FHR correlations and differences in accelerations and decelerations in acidemic fetuses. The auROC ranged between 0.50 for FHR accelerations and 0.77 for MHR baseline plus FHR STV.

Conclusions: MHR and FHR respond differently during labor with signs of increased maternal–fetal attachment during labor progression in acidemic fetuses. Combined MHR–FHR analysis may help to improve prediction of newborn acidemia compared with FHR analysis alone.     

脐血乳酸水平及胎心监护图形预测胎儿窘迫的价值

目的　探讨新生儿脐动脉血乳酸水平及胎心监护图形预测胎儿窘迫的价值。方法　测定 73例胎心监护图形为不良图形 (胎心基线异常、重度变异减速、轻度变异减速、心动过速 )的新生儿(病例组 )和 118例产前无胎儿窘迫征象 ,出生后 1分钟Apgar评分≥ 9分的新生儿 (对照组 )出生后脐动脉血乳酸水平。结果　病例组中产钳助产率明显高于对照组 (P <0 0 1) ,顺产率低于对照组 (P<0 0 1)。病例组中 ,胎心重度变异减速多发于第二产程 ;胎心基线异常的新生儿Apgar评分≤ 7分的发生率高于重度变异减速、轻度变异减速、心动过速的新生儿 (P <0 0 5 )。病例组中 ,胎心基线异常者脐动脉血乳酸水平为 (4 5 5± 0 2 3 )mmol/L ;重度变异减速者为 (3 84± 0 40 )mmol/L ,出现以上两种图形的新生儿脐动脉血乳酸水平均明显高于对照组 (P <0 0 1)。轻度变异减速者脐动脉血乳酸水平为 (2 63± 0 3 2 )mmol/L ;心动过速者脐动脉血乳酸水平为 (2 5 5± 0 46)mmol/L。并且轻度变异减速与心动过速者脐动脉血乳酸水平与对照组比较 ,差异无显著性 (P >0 0 5 )。结论　测定新生儿脐动脉血乳酸水平是一种有效、准确的诊断胎儿窘迫的方法。胎心基线异常、重度变异减速与胎儿窘迫的发生密切相关 ;轻度变异减速、心动过速与胎     

Fetal umbilical artery flow velocity waveforms: prediction of small for gestational age infants and late decelerations in labour

The relationship between fetal umbilical artery waveform patterns and (a) small for gestational age infants or (b) late fetal heart rate (FHR) decelerations in labour was examined in 205 clinically high-risk pregnancies. All pregnancies were studied using continuous-wave Doppler Ultrasound within 7 days of delivery. Waveforms were analysed by calculating a ratio of peak systolic frequency to end diastolic frequency (A/B ratio). An abnormal Doppler result was defined as being above the 97th centile for gestation from our previously derived normal values. Abnormal Doppler results occurred in only 38% of small for gestational age (SGA) infants and in 70% of those developing late decelerations in labour. Doppler ultrasound is a poor predictor of SGA infants, but may identify a high proportion of cases at risk of developing late FHR decelerations in labour.     

Predictive value of electronic fetal monitoring for intrapartum fetal asphyxia with metabolic acidosis

Objective: To determine the predictive value of each fetal heart rate (FHR) variable and of patterns of FHR variables for fetal asphyxia during labor.Methods: This matched case-control study included an asphyxia group of 71 term infants with umbilical artery base deficit greater than 16 mmol/L and a control group of 71 term infants with umbilical artery base deficit less than 8 mmol/L. Each FHR record available for the 4 hours before delivery was scored in 10-minute cycles for each FHR variable. Selected patterns of important FHR variables were examined during the last hour before delivery for their predictive value for fetal asphyxia.Results: The FHR variables associated with fetal asphyxia included absent and minimal baseline variability and late and prolonged decelerations. Fetal heart rate patterns with absent baseline variability were the most specific but identified only 17% of the asphyxia group. The sensitivity of this test increased to 93% with the addition of less specific patterns. The estimated positive predictive value ranged from 18.1% to 2.6%, and the negative predictive value ranged from 98.3% to 99.5%.Conclusion: A narrow 1-hour window of FHR patterns including minimal baseline variability and late or prolonged decelerations will predict fetal asphyxial exposure before decompensation and newborn morbidity. Thus, with careful interpretation, predictive FHR patterns can be a useful screening test for fetal asphyxia. However, supplementary tests are required to confirm the diagnosis and to identify the large number of false-positive patterns to avoid unnecessary intervention.     

Reliability of intrapartum fetal heart rate monitoring in the postterm fetus with meconium passage

Fifty-six postterm fetuses with intrapartum meconium passage underwent routine scalp stimulation and scalp blood sampling. Fetal heart rate (FHR) patterns were compared with blood pH. Nine fetuses (16%) had a scalp pH less than 7.20. Twenty-nine fetuses (54%) demonstrated spontaneous or induced FHR accelerations; none were acidemic. Acidemia with normal variability was found only in conjunction with severe variable decelerations, and may represent respiratory acidosis. In this group, two of nine acidemic fetuses demonstrated no decelerations (pH 7.04) or mild variable decelerations only (pH 7.19). The absence of late decelerations was not as reliable as the presence of accelerations in the prediction of fetal well-being. Thirty-three percent of the fetuses who failed to exhibit spontaneous or provoked FHR accelerations were acidemic. These findings suggest that in this high-risk group of fetuses, the absence of spontaneous FHR accelerations should be followed by an attempt to induce accelerations, scalp pH assessment, or cesarean section.     

第一产程异常胎心监护图形与新生儿结局的关系

目的　探讨第一产程异常胎心监护图形与新生儿结局的关系。方法　回顾分析 2 0 0 2年 8月至 2 0 0 3年 6月在我院足月单胎头位分娩产妇 ,第一产程中胎心率 (FHR)异常图形 2 1 7例 (观察组 )和FHR正常图形的2 6 9例 (对照组 )的临床资料。结果　第一产程异常FHR图形的发生率为 4 4 7% ,常见类型为轻度变异减速(6 4 5 % )、基线变异减弱 (2 1 6 % )和轻度心动过速 (1 2 0 % )。晚期减速、基线变异减弱和重度变异减速是导致新生儿窒息的危险因素。观察组羊水过少 (5 1 % )、脐带缠绕 (2 2 6 % )、羊水粪染 (1 0 6 % )、新生儿窒息 (6 5 % )、新生儿转入NICU(1 0 1 % )的发生率和剖宫产率 (31 8% )明显高于对照组 (P <0 0 5 )。结论　第一产程异常FHR图形的发生率较高 ,其中晚期减速、基线变异减弱、重度变异减速与新生儿窒息的发生相关 ,其他图形可在严密监护下继续试产     

Computerized analysis of the fetal heart rate in pregnancies complicated by preterm premature rupture of membranes (pPROM).

OBJECTIVE: We aimed to show that in pregnancies complicated by preterm premature rupture of membranes (pPROM), there are alterations to the fetal heart rate pattern that can be detected by computerized analysis. METHODS: The study population consisted of 27 pregnant women with pPROM at 29-34 weeks of gestation and 33 normal pregnancies matched according to age, parity and gestation. A 30-minute fetal heart rate (FHR) tracing was analyzed by computer and umbilical artery cord blood was collected at birth. RESULTS: The baseline heart rate, the number of decelerations exceeding 20 beats per minute and the duration of episodes of low variation were higher in the pPROM group versus the controls. The number of decelerations exceeding 20 beats per minute had an independent, statistically significant association with umbilical artery pH at birth. CONCLUSIONS: Even if our data require a prospective validation involving a larger number of pathological cases, a computerized FHR tracing analysis may improve the clinical care and the timing of delivery during pPROM by definition of the risk of acidemia and pre-acidemia.     

Antenatal fetal heart-rate variability in relation to fetal acid-base status at caesarean section

Summary. A quantitative comparison was made of fetal heart-rate (FHR) traces obtained shortly before delivery, and of umbilical artery blood gas values, in 49 women delivered by caesarean section for reasons other than fetal compromise and in 23 women delivered by section for antenatal fetal compromise judged from visual inspection of conventional FHR recordings. The FHR traces in the compromised group of fetuses were abnormal, with low variability and a high incidence of decelerations, but there was no significant difference from the normal group in metabolic acidaemia, as judged by the base excess of umbilical artery blood. The compromised group consisted almost exclusively of infants small-for-gestational age. These results suggest that the FHR pattern of the compromised fetuses is not the direct result of intrauterine asphyxia but of some other factor associated with growth retardation.     

Mechanisms of late decelerations in the fetal heart rate. A study with autonomic blocking agents in fetal lambs.

Fetal heart rate decelerations resembling the late deceleration FHR pattern were produced in fetal sheep by periodic occlusion of the maternal common hypogastric artery for 30-60 sec. Transient fetal hypertension also occurred during the occlusions. Alpha-adrenergic blockade with phentolamine eliminated or markedly reduced the hypertensive response. FHR decelerations still occurred intermittently with some occlusions; however, their character was greatly altered. After parasympathetic blockade with atropine, the decelerations were replaced by periodic FHR accelerations during the occlusions. These accelerations were, in turn, eliminated by the beta-adrenergic blocking agent, propranolol. In the presence of combined parasympathetic, alpha- and beta-adrenergic blockade, the FHR remained essentially constant during the hypogastric artery occlusions in non-acidemic fetuses. FHR decelerations persisted after parasympathetic or total autonomic blockade when the fetuses were significantly hypoxic, as judged by depressed arterial blood pH and base excess values. Beat-to-beat variability of the baseline FHR persisted in the face of severe hypoxia and acidosis. These observations demonstrate that reflex mechanisms are involved importantly in the genesis of late deceleration FHR patterns in the acutely hypoxemic fetus, but that direct depression of myocardial rhythmicity becomes a factor as hypoxic acidosis develops.     

Heart rate variation and movement incidence in growth-retarded fetuses: the significance of antenatal late heart rate decelerations

In 37 intrauterine growth-retarded fetuses, combined 1-hour recordings of fetal heart rate and body movements were made within 24 hours of elective cesarean section. Fetal body movements were recorded simultaneously by use of real-time ultrasound. The study group was divided into two subgroups, according to the presence (n = 29) or absence (n = 8) of antepartum late heart rate decelerations. Correlations were made with umbilical blood gas values obtained immediately after cesarean section. Baseline heart rate variation was reduced below the normal range in 88% of the intrauterine growth-retarded fetuses with decelerations but in only 37% of the group without decelerations. A reduction in fetal heart rate accelerations and body movements and an increase in mean heart rate also were observed only in the group with decelerations. Late heart rate decelerations were associated with low PO2 values in both umbilical artery and vein. It is concluded that in intrauterine growth-retarded fetuses reduced heart rate variation and movement incidence correlate with the presence of late heart rate decelerations before birth and with hypoxemia at birth.     

Late second-trimester nonstress test characteristics in preterm delivery before 32 weeks of gestation

OBJECTIVE: To clarify electronic fetal heart rate (FHR) monitoring characteristics in pregnancies with preterm delivery before 32 weeks of gestation, using the late second-trimester nonstress test. METHODS: Among 953 children born from 1993 to 1996, we identified 100 singleton infants born before 32 weeks of gestation in whom second-trimester (24-27 weeks of gestation) electronic fetal monitoring (EFM) records were obtained. Individual components of the FHR patterns [baseline rate, baseline FHR variability, presence of acceleration (at least 10 beats/min for at least 10 s) and periodic or episodic deceleration (at least 25 beats/min for at least 15 s)] and birth characteristics were compared between pregnancy with or without second-trimester decelerations. RESULTS: Among 100 infants, 65 had and 35 did not have second-trimester decelerations. There were no significant differences in gestational age at birth, birth weight, cord arterial blood pH, Apgar score and meconium staining between pregnancies with second-trimester decelerations and those without second-trimester decelerations. There were no significant differences in baseline rate and baseline variability between pregnancies with or without second-trimester decelerations. The number of accelerations in pregnancies with second-trimester decelerations was significantly more frequent than that in pregnancies without second-trimester decelerations (p < 0.001). There was a significant increase in the occurrence of premature rupture of the membranes (PROM; 60.0%) in pregnancies with second-trimester decelerations, when compared with events (37.1%) related to pregnancies without second-trimester decelerations (p < 0.05). There were no significant differences in the onset of breech presentation, cervical incompetency, preeclampsia and abnormal FHR pattern at birth between pregnancies with second-trimester decelerations and those without second-trimester decelerations. Pregnancies with PROM after second-trimester EFM were significantly more likely to have second-trimester decelerations than those without PROM (75.0 vs. 54.2%, p < 0.05). CONCLUSION: Periodic or episodic decelerations during late second-trimester EFM were associated with an increased risk of the occurrence of PROM in pregnancies with preterm delivery before 32 weeks of gestation.     

Antenatal fetal heart-rate variability in relation to fetal acid-base status at caesarean section

A quantitative comparison was made of fetal heart-rate (FHR) traces obtained shortly before delivery, and of umbilical artery blood gas values, in 49 women delivered by caesarean section for reasons other than fetal compromise and in 23 women delivered by section for antenatal fetal compromise judged from visual inspection of conventional FHR recordings. The FHR traces in the compromised group of fetuses were abnormal, with low variability and a high incidence of decelerations, but there was no significant difference from the normal group in metabolic acidaemia, as judged by the base excess of umbilical artery blood. The compromised group consisted almost exclusively of infants small-for-gestational age. These results suggest that the FHR pattern of the compromised fetuses is not the direct result of intrauterine asphyxia but of some other factor associated with growth retardation.     

Short-term fetal heart rate variation, decelerations, and umbilical flow velocity waveforms before labor.

OBJECTIVE: To determine the value of computerized antepartum measurements of short-term fetal heart rate (FHR) variation and decelerations as a predictor of outcome, and to compare these with measurements of the umbilical artery flow velocity waveform. METHODS: Data were collected from 3563 high-risk patients for measurements of FHR variables (15,702 records) and outcome (intrauterine death or metabolic acidemia on delivery). Detailed analyses were made on 89 patients with one or more records in which short-term FHR variation was 3 milliseconds or less. Umbilical artery flow velocity waveforms were measured concurrently on 2441 occasions in 991 patients. RESULTS: More than half of the patients with FHR variation of 3 milliseconds or less were identified before 31 weeks. When short-term FHR variation exceeded 3 milliseconds, there were no intrauterine deaths and only one instance of metabolic acidemia on cesarean delivery. When FHR variation fell below 2.6 milliseconds, 34% of the subjects had metabolic acidemia on cesarean or intrauterine death. The appearance or absence of decelerations was an unreliable guide to outcome. The correlation between FHR variation and the umbilical artery flow velocity waveform was low (r = 0.32). The population studied contained some patients without placental vascular disease or, in five with pre-eclampsia, without abnormal umbilical artery velocity waveforms but with grossly reduced FHR variation. CONCLUSION: Reduction in short-term FHR variation, as measured by computer, reliably predicts fetal outcome and is a more general measure of fetal well-being than are umbilical artery flow velocities.     

Significance for fetal outcome of poor prognostic features in fetal heart rate traces with variable decelerations

OBJECTIVE: To determine the clinical significance of the existence of poor prognostic features in fetal heart rate (FHR) traces with variable decelerations. STUDY DESIGN: This study was prospectively performed on 167 randomly selected women with a singleton pregnancy at term. Ninety-one patients had an FHR trace without pathological features. The remaining 76 women had variable decelerations and their FHR traces were analyzed carefully for the existence of poor prognostic features. Fetal and neonatal outcomes were compared in the normal and variable deceleration groups. RESULTS: There were statistically significant differences between the groups in 1 and 5 minute Apgar scores, fetal heart rate (FHR), umbilical artery blood pH, pCO2; whereas no significant differences were found in the levels of umbilical artery HCO3, pO2. CONCLUSION: Prolonged deceleration had the highest specificity for 1 minute Apgar score < 7.5 minute Apgar score < 7 and umbilical artery blood pH < 7.20 (95.0%, 96.3%, 97.5%, respectively). Loss of variability during deceleration showed the highest specificity for the same fetal features (66.7%, 72.3%, 63.9%, respectively). All other poor prognostic features had high specificities but low sensitivities.     

Nuchal cords and neonatal outcome

To assess the significance of nuchal cords, 110 affected woman-infant pairs at term gestation were compared with 110 control pairs. Newborns with a nuchal cord had an increased prevalence of umbilical artery acidemia (22 of 110 versus 13 of 110; P less than .05) and more variable fetal heart rate (FHR) decelerations in the first stage of labor (mild = 41 versus 20; P less than .0001; moderate-severe = 21 versus 5; P less than .0001) and the second stage of labor (moderate-severe = 46 versus 21; P less than .0001). In newborns with a nuchal cord, the umbilical artery acidemia was usually mixed (68%) or respiratory (23%) in origin, and pure metabolic acidemia was infrequent (9%). We conclude that nuchal cords are associated with an increased prevalence of variable FHR decelerations in the first and second stages of labor and with an increased incidence of umbilical artery acidemia.     

Umbilical artery blood flow velocity waveforms during variable deceleration of the fetal heart rate

Blood flow velocities of the umbilical arteries were measured by Doppler ultrasonography during variable decelerations of the fetal heart rate. The flow velocity waveforms, being normal between uterine contractions, showed either an unchanged flow velocity waveform with an exclusive fetal heart rate effect on end-diastolic velocities or a rapid change to absent and reverse diastolic flow during the decelerations, indicating an abrupt increase in placental resistance with a halt in placental perfusion. Computer-aided reconstruction of the fetal heart rate curve revealed the exact temporal relationship between the reduction of umbilical artery perfusion and deceleration of fetal heart rate. We showed that variable decelerations of fetal heart rate can be observed during only slightly changed umbilical perfusion or can be caused by a halt in placental perfusion, which does not necessarily mean an absence of any movement of the fetal blood column, but is a result of a systolic forward and diastolic reverse flow to the same extent.     

Course and predictive value of fetal heart rate parameters

The present study concerns the developmental character of the fetal heart rate (FHR) pattern and the implications of predicting the perinatal outcome. Data from 443 patients undergoing 2193 nonstress tests were analyzed retrospectively. We found a significant increase of accelerations more than 15 beats/min, of accelerations associated with fetal movements, of fetal movements registered by the tocotransducer, the frequency of oscillations, and of the Fischer score values throughout gestation. The number of short FHR decreases and the mean baseline level declined throughout gestation. A long duration of absent or reduced baseline variability registered even 6 weeks before delivery was associated with low Apgar score values. Late decelerations and contractions registered early in pregnancy were also correlated to a poor outcome. Tachycardia and a low number of accelerations were only correlated to a poor perinatal outcome shortly before the delivery. Fetal movements not associated with FHR accelerations were an early indicator of a poor neonatal outcome. Scoring systems did not generally improve the predictive value of FHR patterns.     

Fetal acidemia and electronic fetal heart rate patterns: is there evidence of an association?

OBJECTIVE: Despite the ubiquity of electronic fetal monitoring, the validity of the relationship between various fetal heart rate (FHR) patterns and fetal acidemia has not yet been established in a large unselected series of consecutive pregnancies. The aim of this study was to examine the published literature for evidence of such a relationship. METHODS: Four hypotheses based on assumptions in common clinical use were examined. The literature was searched for relationships between certain aspects of FHR patterns (e.g., degree of FHR variability, depth of decelerations), and fetal acidemia, or fetal vigor (5-minute Apgar score >or=7). We also attempted to relate duration of these patterns to the degree of acidemia. Using standardized FHR nomenclature we defined patterns based on baseline FHR variability, baseline rate, decelerations, and accelerations. RESULTS: The following relationships were observed: (1) Moderate FHR variability was strongly associated (98%) with an umbilical pH >7.15 or newborn vigor (5-minute Apgar score >or=7). (2) Undetectable or minimal FHR variability in the presence of late or variable decelerations was the most consistent predictor of newborn acidemia, though the association was only 23%. (3) There was a positive relationship between the degree of acidemia and the depth of decelerations or bradycardia. (4) Except for sudden profound bradycardia, newborn acidemia with decreasing FHR variability in combination with decelerations develops over a period of time approximating one hour. Most studies identified were observational and uncontrolled (grade III evidence of US Preventive Services Task Force); however, there was general agreement amongst the various studies, strengthening the validity of the observations. CONCLUSIONS: The validity of the relationship between certain FHR patterns and fetal acidemia and/or vigor, is supported by observations from the literature. In addition four assumptions commonly used in clinical management are supported. These conclusions need to be confirmed by a prospective examination of a large number of consecutive, unselected FHR patterns, and their relationship to newborn acidemia. Pending the completion of such studies, these observations can be used to justify certain aspects of current clinical management, and may assist in standardizing the diversity of opinions regarding FHR pattern management.     

The effects of different concentrations of cocoa in the chocolate intaken by the mother on fetal heart rate

Abstract

Objective: To analyze the effects of different concentrations (30% and 80%) of cocoa on fetal heart rate (FHR).

Study design: One hundred pregnant women with uncomplicated gestation, matched for age and parity, underwent computerized FHR recording before and after the consumption of 30?g of 30% and 80% cocoa chocolate. After 1 week, those who had received 30% were shifted to 80% and vice versa to have a crossover. Computerized cardiotocography parameters (contractions, fetal movements, baseline FHR, accelerations greater than 15 bpm for 15?s, number of decelerations, minutes of high variability, short term variability in ms) were recorded and expressed as mean and SD. The differences were tested for statistical significance using the paired t test, with the significance at p?<?0.05. The percent change after chocolate intake for accelerations and short-term FHR variation was calculated.

Results: The number of fetal movements, accelerations, the duration of episodes of high variation and the short-term FHR variation were significantly higher (p?<?0.0001) after 80% cocoa intake. After 30% cocoa chocolate intake, only the number of accelerations was significantly increased. The percent change of the number of accelerations and the short-term FHR variation were significantly higher after 80% cocoa chocolate maternal intake.

Conclusions: Maternal intake of dark chocolate has a stimulating action on fetal reactivity. The effect is more marked with high concentrations (80%) of cocoa. This finding is likely due to the pharmacological action of theobromine, a methilxanthine present in cocoa.