Intrapartum Fetal Heart Rate Patterns Research Articles

Do fetal heart rate deceleration patterns during labor differ between various umbilical cord abnormalities?

To examine differences in intrapartum fetal heart rate (FHR) patterns among cases with various cord abnormalities. Vertex singleton cases with nuchal cord (226 cases), velamentous (12 cases), marginal cord insertion (53 cases) or hyper-coiled cord (39 cases) and without them (466) that were delivered at our hospital were examined. The relationship between cord abnormalities and intrapartum FHR patterns were retrospectively investigated. Deceleration patterns were analyzed for the presence of variable, early, late and prolonged decelerations. The frequencies of each FHR pattern per uterine contraction were assessed during 30 uterine contractions at the end of the first stage and throughout the entire second stage of labor. In the first stage of labor, frequencies of variable decelerations were 34.5+/-23.8% and 27.3+/-25.5% in cases with velamentous insertion and hyper-coiled cord, respectively. These were significantly higher than in controls (11.7+/-17.3%, P<0.0001). In the second stage of labor, however, frequencies of each deceleration were not different among various cord abnormalities. Fetal heart rate tracing from the first stage of labor is indicated in cases with the prenatal diagnosis of velamentous insertion or hyper-coiling of the cord.

Intrapartum fetal heart rate patterns in infants (≥ 34 weeks) with poor neurological outcome

Background Cases suggestive of non-acidemia related cerebral palsy (CP) are likely misdiagnosed as acidemia related CP because of the presence of nonreasuring fetal heart rate (FHR) patterns. Aims Our purpose was to compare intrapartum FHR patterns between the cases of neurological damage and the cases without disability after severe metabolic acidemia and neonatal encephalopathy, and also to compare the FHR patterns between cases with CP due to asphyxia and cases with CP of other etiology in infants born after 34 weeks. Study design From 1998 to 2003, our peer review conferences determined 136 infants with high-risk factors for neurological impairment in the unselected 65,197 live births. High-risk infants were chosen according to our criteria. Among them 58 were eligible infants because they were born at ≥ 34 weeks of gestation and also had legible FHR traces. Outcome measures Incidence of nonreassuring FHR patterns. Results Fifteen infants were acidemia related and 43 were non-acidemia related high-risk infants. Ten of the 15 acidemia infants developed CP and all had shown bradycardia ≥ 13 min with a nadir < 80 bpm. In the 43 non-acidemia infants, 35 had CP, mental retardation, epilepsy, or hearing loss and 74% (26/35) of them had shown nonreassuring FHR patterns. Incidence of severe bradycardia was significantly elevated in the acidemia related CP compared with acidotic infants without disability, and those with non-acidemia related CP. Conclusions Even in infants with non-acidemia related CNS impairments, who were born at ≥ 34 weeks of gestation, 74% had shown intrapartum nonreassuring FHR patterns.

Intrapartum Fetal Heart Rate Pattern in Oligohydramnios

Objectives: It was the aim of this study to examine intrapartum fetal heart rate (FHR) patterns in oligohydramnios. Methods: Subjects comprised 24 singleton pregnant women diagnosed with oligohydramnios and 470 controls. FHR patterns were analyzed at the end of the first stage and throughout the whole second stage of labor. Numbers of variable deceleration (VD), early deceleration (ED), late deceleration (LD) and prolonged deceleration (PD) per contraction were counted. Results: Frequencies of decelerations in oligohydramnios and controls were 5.4 ± 14.5 and 2.0 ± 6.6% for ED, 0.0 and 0.4 ± 2.5% for LD, 17.6 ± 20.6 and 12.2 ± 13.3% for VD, and 1.8 ± 3.7 and 0.8 ± 3.0% for PD in the first stage of labor. In the second stage, frequencies were as follows: 5.1 ± 10.5 and 1.5 ± 6.1% for ED, 0.5 ± 1.7 and 1.0 ± 4.4% for LD, 30.1 ± 22.0 and 43.9 ± 29.3% for VD, and 29.3 ± 33.2 and 12.6 ± 22.5% for PD. Conclusions: In cases of oligohydramnios, ED occurred frequently from the first stage of labor. In the second stage of labor, the frequency of PD was extremely high and the frequency of VD was low.

Acute Tocolysis for Uterine Activity Reduction in Term Labor

This review critically evaluates the efficacy of different tocolytics in reducing uterine pressure and contractions in term labor. The available evidence supports the use of beta-adrenergic-receptor agonists such as terbutaline or ritodrine; they appear to have an immediate and comparable profound effect on uterine activity in term labor. However, the preferred type of beta-adrenergic receptor agonist and dosage are unclear. The oxytocin receptor antagonist atosiban has a high specificity for the uterus with limited or no systemic effects and could therefore be an attractive alternative for use in term labor. The evidence on the tocolytic potency of a single bolus of atosiban for tocolysis in term labor is encouraging but limited and needs further research. Moreover, atosiban lacks United States Food and Drug Administration approval. Literature documenting efficacy and safety of nitroglycerin or magnesium sulfate in term labor is far from convincing. The theoretical basis for the use of tocolytics for nonreassuring intrapartum fetal heart rate patterns is to reduce the aggravating influence of uterine contractions. However, the clinical evidence that tocolytics in term active labor are actually beneficial in improving neonatal outcome is very limited.

Effect of Chronic Maternal Methadone Therapy on Intrapartum Fetal Heart Rate Patterns

Treatment of maternal opioid dependence with methadone is associated with a delay in fetal heart rate (FHR) accelerations in nonstress tests. The objective of this investigation was to determine the effect of methadone maintenance therapy on intrapartum FHR patterns. This retrospective cohort study compared intrapartum FHR tracings from 56 methadone-treated patients > or =36 weeks gestation with a control group of nonsubstance using patients matched for maternal age, parity, gestational age, and ethnicity. Blinded FHR interpretation included the recording of baseline, variability, accelerations, and late or severe variable decelerations. The 8-point FHR scoring system was based on the National Institute of Child Health and Human Development Research Planning Workshop guidelines. We considered a 25% reduction in the score during the latent phase to be significant. The median maintenance dose of methadone was 70 mg daily, with a range between 20 mg and 130 mg. Each patient tested negative for other substances on urine screening before admission. The significantly lower FHR score in the methadone group (mean difference, 1.4; 95% confidence interval, 1.1 to 1.7) was attributed to a lower baseline (P <.05), less moderate or marked variability (P <.01), and a lower proportion of accelerations during the first stage of labor (P <.01). A higher proportion of methadone-exposed fetuses had late or severe variable decelerations in the second stage (44.2% vs 22.9%; P <.03). Analgesic needs, operative vaginal or cesarean delivery rates, and Apgar scores less than 7 at 1 and 5 minutes were not significantly different between the two groups. Chronic maternal methadone treatment affects intrapartum FHR patterns by reducing the variability, baseline, and proportion of accelerations during the first stage. These subtle drug-induced effects do not compromise intrapartum decision-making or immediate newborn adjustments.

Intrapartum late deceleration develops more frequently in pre‐eclamptic women with severe proteinuria

Our purpose was to investigate the effect of proteinuria associated with pre-eclampsia on intrapartum fetal heart rate patterns. A retrospective study was performed involving 79 pregnant women with pre-eclampsia and 19 pregnant women with gestational hypertension (GH). Pre-eclampsia was then classified into two groups according to the degree of proteinuria (> or = or < 3 + dipstick), which was classified as severe urinary protein (UP; n = 35) and mild UP (n = 44) at delivery. Intrapartum fetal heart rate (FHR) monitoring was classified as either no deceleration, moderate variable deceleration, severe variable deceleration (sVD), prolonged deceleration (PD), occasional deceleration or recurrent late deceleration (rLD). We evaluated the prevalence of non-reassuring FHR (sVD, PD or rLD), the prevalence of intrauterine growth restriction (IUGR), and cord blood gas status in the three groups. The prevalence of non-reassuring FHR and cord blood gas status of these three groups was also compared with their prevalence in 65 women with low-risk pregnancies. Multiple logistic regression analysis was performed to determine the association between rLD and maternal-fetal parameters. Levels of systolic and diastolic blood pressure were similar among the three groups. Severe UP was diagnosed significantly earlier, was associated with significantly lower gestational age, and infants with lighter birth weight (P < 0.05) compared with GH and mild UP. The prevalence of IUGR in severe UP was higher than in GH (54%v. 21%, P < 0.05); however, no differences were found in the prevalence of IUGR between mild and severe UP (43%v. 54%, P = 0.33). The prevalence of non-reassuring FHR in GH was not statistically significant in the low-risk pregnancies (5%v. 9%, P = 0.58). In mild and severe UP, the non-reassuring FHRs were more predominant (30% and 43%, respectively) than in low-risk pregnancies and GH (P < 0.05). The rLD was more common in the group with severe UP and accounted for 40% of all FHR patterns. There was no difference in the incidence of low pH among the groups. However, fetuses in pregnancies involving severe UP were significantly hypoxemic when compared with others. Multiple logistic regression analysis showed that worsening proteinuria (odds ratio [OR], 5.5; 95% confidence interval [CI], 2.4-12.9) and IUGR (OR, 3.8; 95% CI, 1.2-11.5) increased the risk of rLD. Rates of preterm birth at less than 32 weeks (OR, 0.7; 95% CI, 0.2-2.5) and severe hypertension (OR, 0.5; 95% CI, 0.2-1.3) were not significant. In pre-eclampsia, the presence of severe proteinuria is associated with an increased likelihood of rLD.

Correlation between intrapartum fetal heart rate pattern and umbilical cord arterial blood gases in low-risk patients

Correlation between intrapartum fetal heart rate pattern and umbilical cord arterial blood gases in low-risk patients

Characteristic intrapartum fetal heart rate patterns in neonates with asphyxiation- and non-asphyxiation-related cerebral palsy

Characteristic intrapartum fetal heart rate patterns in neonates with asphyxiation- and non-asphyxiation-related cerebral palsy

Velamentous cord insertion and atypical variable decelerations with no accelerations

Objectives: To examine intrapartum fetal heart rate (FHR) patterns in the presence of velamentous cord insertion (VCI). Methods: The site of cord insertion was determined in 1460 women on antenatal ultrasonographic and postnatal examinations. Each of 24 women with pregnancies complicated with VCI was matched at the onset of labor with 10 women who had a normal pregnancy, and FHR patterns were analyzed for both cases and controls. Results: Compared with controls, cases of variable decelerations with no accelerations (VDNA) during the first and second stages of labor were more frequent in women with VCI (first stage: 25% vs. 5.1%, second stage: 65.0% vs. 21.7%, P < 0.001). The adjusted odds ratio associated with VDNA occurrence in women with VCI was 3.83 (95% confidence interval [CI]: 1.51–9.72, P = 0.005). The mean odds ratio associated with length of aberrant vessels in women with VCI plus VDNA was 1.38 (95% CI: 1.04–1.83, P = 0.026). Conclusion: Pregnancies complicated with VCI are associated with a higher rate of VDNA.

Intrapartum fetal heart rate monitoring in cases of cytomegalovirus infection

ObjectiveSeveral studies have shown that abnormal intrapartum fetal heart rate patterns are the results from pre-existing fetal brain damage. We evaluated intrapartum fetal heart rate pattern of cytomegalovirus-infected fetuses and correlated the patterns with neurologic outcomes. Study designBetween 1991 and 2001, there were 20 cytomegalovirus-infected fetuses. We selected 40 fetuses as control subjects that were matched for gestational age and birth weight. Fetal heart rate was interpreted according to the guidelines of the National Institute for Child and Human Development. The incidence of abnormal fetal heart rate pattern and umbilical blood gases were compared between both groups. We also investigated the factors that contributed to abnormal fetal heart rate pattern in the cytomegalovirus group. ResultsNonreassuring fetal heart rate patterns (prolonged deceleration and recurrent late deceleration) were observed in 8 of 20 fetuses (prolonged deceleration, 7 fetuses; recurrent late deceleration, 1 fetus) in the cytomegalovirus group and in 3 of 41 fetuses (prolonged deceleration, 1 fetus; recurrent late deceleration, 2 fetuses) in the control group (P<.05, Fisher test). Baseline fetal heart rate variability was minimal in 4 of the 7 prolonged deceleration cases in the cytomegalovirus group. Umbilical pH <7.1 was found for 1 fetus in the cytomegalovirus group. The average umbilical arterial pH values were similar in both the groups. In the cytomegalovirus group, there were no differences in the incidence of contributing factors between 8 fetuses with abnormal fetal heart rate pattern (prolonged deceleration and recurrent late deceleration) and 8 fetuses with no change. There were 3 fetuses with cerebral palsy: 2 fetuses in the no change group and 1 fetus in the prolonged deceleration group. Antigenemia was positive exclusively in 4 cases with abnormal fetal heart rate pattern (P<.05). ConclusionCytomegalovirus-infected fetuses are more likely to show abnormal intrapartum fetal heart rate patterns than low-risk control fetuses, which suggests that the perinatal detection of cytomegalovirus is necessary to distinguish hypoxic-ischemic encephalopathy.

Comparison of intrapartum fetal heart rate tracings in patients with neonatal seizures vs. no seizures: what are the differences?

To determine which intrapartum fetal heart rate parameters in the presence of severe neonatal acidosis (pH < 7.0) appropriately predicts the development of neonatal seizures in the context of hypoxic ischemic encephalopathy (HIE). The intrapartum fetal heart rate tracings of 25 neonates who developed neonatal seizures secondary to HIE were compared with 25 matched neonates with similar pH and gestational age who did not develop seizures. All patients had at least 2 hours of intrapartum fetal heart rate patterns available for review. We compared the fetal heart rate parameters of prolonged deceleration, variable and late decelerations, variability, accelerations, fetal heart rate baseline and duration of the fetal heart rate abnormality. Comparison between the groups was done using chi-square for nominal data and student t-tests for continuous data. Neonates with seizures 2 degrees HIE had a significantly longer duration of abnormal fetal heart rate patterns (72 +/- 12 minutes vs 48 +/- 12 minutes, p < 0.001). This study demonstrated that in the setting of neonatal acidosis the development of seizures is related to the period of stress (duration of the abnormal fetal heart rate pattern).

Intrapartum fetal heart rate patterns in the prediction of neonatal acidemia

Objective: This study was undertaken to correlate changes in the intrapartum electronic fetal heart rate patterns with the development of significant neonatal acidemia. Study Design: We identified 488 fetuses at a gestational age of >37 weeks' gestation who had continuous electronic fetal monitoring during labor for the last 2 hours and umbilical artery cord gas analysis performed at delivery. One investigator blinded to the cord gas outcome reviewed all 488 tracings using the National Institute of Child Health and Human Development guidelines for fetal heart rate monitoring. All fetal heart rate tracings with bradycardia were removed from further analysis. The patients were placed in six groups, depending on the absence or presence of normal variability (amplitude >5 beats) during the last hour of monitoring combined with the absence of decelerations or the presence of variable or late decelerations. The relationship between changes in variability and the outcome variables of pH and base deficit in the six groups was assessed with analysis of variance and χ2 test. Significance was set at the P <.05 level. Results: Patients with normal variability and accelerations, even in the presence of late decelerations or variable decelerations, maintained an umbilical artery pH 7.0 or greater in more than 97% of cases. In the presence of minimal/absent variability (amplitude <5) for at least an hour, the incidence of significant acidemia (pH <7.0) ranged from (12%-31%). Conclusion: The most significant intrapartum fetal heart rate parameter to predict the development of significant acidemia is the presence of minimal/absent variability for at least 1 hour as a solitary abnormal finding or in conjunction with late decelerations in the absence of accelerations. Urgent delivery should be considered in these cases after appropriate ancillary testing. (Am J Obstet Gynecol 2003;188:820-3.)

Prenatal Sonographic Diagnosis of Vasa Previa: Ultrasound Findings and Obstetric Outcome in Ten Cases

In vasa previa, a condition in which fetal vessels course within the membranes between the presenting part and the cervix and are unprotected by Wharton's jelly, there is danger that the vessels will be compressed during labor and tear when the membranes rupture. Fetal exsanguination is a possibility. Vasa previa also can cause abnormal intrapartum fetal heart rate patterns. Ultrasonography now offers the possibility of identifying this anatomical variant well before the onset of labor. The authors report 11 cases of vasa previa, unaccompanied by placenta previa, that were diagnosed prospectively by color Doppler sonography among 33,208 women during the years 1991-1998. Patients were offered elective operative delivery after fetal lung maturity was documented but before the onset of labor. Transabdominal sonography now includes a routine attempt to image the insertion of the cord into the placenta. A color Doppler or color power angio sweep is made across the lower uterine segment to find velamentous vessels overlying the cervix. The diagnosis of vasa previa was confirmed at delivery in 10 cases, and one woman was thought to have a marginal placenta previa. Type I vasa previa, with a single placental lobe and a velamentous cord insertion, was diagnosed in two cases, and type II (vessels over the cervix connected between lobes of a multilobed placenta) in eight. With one exception, placenta previa was described at initial sonography. All but 2 of the 10 patients with established vasa previa had vaginal bleeding in the third trimester, and five were admitted to the hospital. Two deliveries occurred before lung maturity was demonstrated, whereas the others took place at 34 to 37.5 weeks' gestation, after confirmed lung maturity. All the infants had normal Apgar scores and survived. The best screening approach for vasa previa may be to perform transvaginal sonography in the late first or early second trimester and targeted sonography when resolving placenta previa or a low-lying bilobed placenta is suspected.

Intrapartum fetal heart rate tracings: accuracy of interpretation is unaffected by level of providers’ training

Objective: The ACOG Technical Bulletin of July 1995 suggests that intrapartum fetal heart rate patterns should be interpreted as reassuring or nonreassuring. The bulletin describes a nonreassuring fetal heart tracing (FHT) as having one or more of the following components: abnormal baseline (ie, tachycardia, decreased variability); the presence of variable decelerations that are persistent, progressively deeper and longer lasting; late decelerations that are persistent; prolonged deceleration greater than 60 seconds; and a sinusoidal heart rate pattern. A reassuring FHT implies the absence of these patterns. We sought to investigate the accuracy of interobserver interpretation of FHT in labor. Method: Three hundred sixty intrapartum FHTs were evaluated by obstetric residents, attendings, nurses, and maternal–fetal medicine specialists (MFMs). Tracings were accompanied by a questionnaire addressing classification of FHT, a proposed approach, and anticipated fetal outcome. Participants were blinded to actual outcomes. Results: 1) Of reassuring FHTs, 96% were identified with no significant difference in rate of identification in each provider group; 2) 80% of nonreassuring patterns were identified with similar rates of identification within each provider group; and 3) there was no significant interobserver difference in the correct interpretation of tracings between residents (75.5%), attendings (81.9%), MFMs (77.4%), and nurses (85%). Conclusion: Our data suggest that theTechnical Bulletin’s recommended classification of intrapartum FHT tracings as reassuring versus nonreassuring is successful in providing a simple, accurate method of recognition regardless of the providers’ level of obstetric training.

Fetal heart rate patterns in 423 brain-damaged infants: an update

Objective: To update our experience with the fetal heart rate (FHR) pattern of singleton term brain-damaged infants. Methods: The FHR patterns of 123 singleton term brain-damaged infants were retrospectively analyzed and compared with 300 previously published cases. Results: For these 423 cases, obstetrical care was provided from 1976 to 1998. With the exception of more recent obstetrical care, the additional 123 cases were statistically similar to the previously published 300 cases. Overall, the admission FHR patterns were reactive: 229 (54%); nonreactive: 175 (41%); bradycardic: 10 (3%); or unclassifiable: 9 (2%). In the reactive group, the FHR did the following: 1) remained reactive: 29 (13%); 2) developed an elevated baseline in association with repetitive decelerations: 107 (47%); or 3) exhibited a sudden prolonged FHR deceleration that lasted until delivery: 93 (40%). In the nonreactive group, the FHR pattern remained nonreactive at a similar baseline rate: 125 (71%); developed a progressive bradycardia: 32 (18%); or developed a prolonged deceleration that lasted until delivery: 18 (10%). Conclusion: Our retrospective review of 123 additional cases continues to demonstrate that brain-damaged fetuses manifest distinctly similar intrapartum FHR patterns that easily can be categorized and identified on the basis of the fetal admission test and subsequent changes in the baseline rate. This distinction, which covers a 22-year period, would appear to be helpful in the management of obstetrical patients in labor.

Fetal heart rate monitoring: interpretation and collaborative management

Effective intrapartum fetal heart rate (FHR) monitoring requires ongoing collaboration among health care providers. Nurses, midwives, and physicians must have a shared understanding of 1) how FHR tracings are interpreted, 2) which FHR patterns are associated with actual or impending fetal acidemia, 3) when and within what time frame the physician or the midwife should be notified of variant FHR patterns, 4) how quickly physicians and midwives should respond when notified of variant patterns, and 5) the indications for and optimal timing of interventions such as operative delivery. This article reviews the literature on FHR monitoring and includes a discussion of the advantages and limitations of different monitoring modalities. An overview of those FHR patterns are associated with presumed fetal acidemia is presented, as well as sample multidisciplinary FHR monitoring guidelines and an exercise in intrapartum FHR pattern evaluation that can be used to initiate development of local FHR monitoring patterns.

Intrapartum fetal heart rate variability and subsequent neonatal cerebral edema

Objective: To determine whether fetal heart rate variability (FHRV) in the neurologically impaired neonate is associated with cerebral edema.Study design: Through retrospective chart review, singleton term infants with neonatal encephalopathy and permanent neurologic impairment were identified in a national registry of brain-injured infants. Cerebral edema was defined as follows: (1) ultrasound-generalized increases in echodensity throughout the brain with loss of normal landmarks or slitlike ventricles, (2) computed tomography scan-low attenuation throughout the brain, or mass effect as evidenced by sulcal effacement, displacement of the midline structures, ventricular distortion, or compression of subarachnoid spaces, and (3) low magnetic resonance imaging signal on T1-weighted images and high signal on T2-weighted images or morphologic change on T1-weighted image detected by gross enlargement of structures or by distortion of normal adjacent structures. Cases with a Hon intrapartum fetal heart rate (FHR) pattern (reactive pattern on admission followed by tachycardia and repetitive FHR decelerations) were selected. These cases were then categorized according to the FHR variability at the end of the monitor strip as follows: average ≥6 bpm or diminished (D) <6 bpm. Exclusion criteria were as follows: (1) nonqualifying FHR pattern—183; (2) no neuroimaging studies within 7 days of birth—48; (3) insufficient data—19; and (4) other—7.Results: Of 300 singleton term brain-injured neonates, 43 (14%) neonates met entry criteria. Prior to birth, the FHRV average was 10 (23%) or diminished (33 [77%]). Of these infants, cerebral edema was found in 18 (42%) patients. But, average FHRV was associated with significantly less cerebral edema (average 1/10 [10%] versus diminished 17/33 [52%] [P = 0.02]).Conclusions: In brain-injured neonates, cerebral edema appears to be associated with the Hon FHR pattern. Cerebral edema also appears to be associated with diminished FHRV. These findings suggest that the presence of average FHRV in the fetus with the Hon FHR pattern is associated with fetal brain injury, but not necessarily neonatal cerebral edema.

Fetal heart rate patterns in term labor vary with sex, gestational age, epidural analgesia, and fetal weight

Objectives: Our purpose was to analyze the previously unreported effect of fetal sex on the fetal heart rate in labor and to measure its magnitude in relation to the effects of other independent clinical variables. Study Design: The last hour of the intrapartum heart rates of 1884 term singleton fetuses collected during routine clinical monitoring over 19 months in Oxford, United Kingdom, was analyzed by computerized techniques. The records were selected for completeness and continuity until within at least 30 minutes of delivery. A subset of records from earlier in labor and a separate archive of antepartum normal term records were also examined. Results: Female fetuses had significantly faster heart rates than male fetuses ( P < .0001). Epidural analgesia, weight percentile (adjusted for age and sex), parity, the duration of first and second stages of labor, and a fall in umbilical arterial blood pH at birth also independently modulated the fetal heart rate (all P < .0001). The effects of these independent variables on heart rate were additive, the most important being epidural analgesia as a cause of tachycardia. The effect of fetal sex was less in the first stage, 6 to 7 hours before delivery, and was not present before the onset of labor (in another 552 pregnancies at 37 to 38 weeks). Conclusions: The fetal heart rate response of female fetuses to normal labor differs from that of male fetuses. Computerized numeric analysis of intrapartum fetal heart rate patterns will need to take into account the multiple factors that influence the fetal heart rate to identify precisely which patterns predict clinical outcome. (Am J Obstet Gynecol 1999;180:181-7.)

The fetal admission test and intrapartum fetal death.

Our objective was to describe the admission and subsequent intrapartum fetal heart rate (FHR) patterns in 21 singleton term pregnancies with an intrapartum fetal death. Through a retrospective chart review, 21 pregnancies with a term intrapartum fetal death were divided into 2 groups based on the fetal admission test (FAT): Group I-reactive (one or more FHR accelerations of 15 bpm x 15 sec in the first 30 min of monitoring); and Group II-nonreactive (NR [the absence of accelerations]). The FAT was compared with the subsequent intrapartum FHR pattern. Of the 21 deaths, the FAT was reactive in 7 fetuses (33%) or NR in 14 fetuses (67%). While the demographic features of these groups were statistically similar, Group II had higher rates of meconium (12 out of 14 (86%) vs. 2 out of 7 [29%] p = 0.017) and admission FHR decelerations (9 out of 14 (64%) vs. 1 out of 7 [14%] p = 0.06). In Group I, a sudden catastrophic event such as a uterine rupture produced a prolonged FHR deceleration in six fetuses (86%). One (14%) fetus died after a Hon pattern. In Group II, four patients had a stair steps to death pattern. Intrapartum fetal death can occur after a reactive or NR FAT. With a reactive FAT, a catastrophic event appears necessary to cause fetal death. The higher rates of meconium, FHR decelerations, and stair steps to death patterns in the NR group suggest the underlying basis for the fetal demise was related to preadmission fetal compromise.

Doppler study of the fetal cardiac function in prolonged pregnancies

To evaluate the association between fetal cardiac function and amniotic fluid index (AFI) in postterm fetuses, and to determine if changes in fetal cardiac function precede the occurrence of nonreassuring intrapartum fetal heart rate (FHR) patterns. Forty-five otherwise low-risk pregnant women between 41 and 43 weeks' gestation were studied longitudinally. Gestational age was confirmed in all patients by ultrasound before 20 weeks' gestation. Each subject had two or three tests performed every 3-4 days, including a non-stress test, a biophysical profile, and Doppler studies of the aortic and pulmonic outflow tracts. Aortic and pulmonic artery flow velocity waveforms were recorded slightly distal to the valves. Peak velocity, velocity time integral, and heart rate were calculated from the flow velocity waveforms we obtained. The change in AFI and aortic and pulmonic peak velocity and [velocity time integral] x [heart rate] were calculated for each fetus. Labor was induced at 42 weeks' gestation in 20 patients, and 17 entered labor spontaneously. Changes in AFI, observed during the follow-up period, correlated significantly with changes in aortic peak velocity (r = 0.54, P < .01) and with aortic outflow [velocity time integral] x [heart rate] (r = 0.60, P < .001) but not with pulmonic peak velocity and [velocity time integral] x [heart rate]. The decrease in aortic peak velocity and aortic and pulmonic [velocity time integral] x [heart rate] was significantly higher (P < .01) in eight fetuses that developed a nonreassuring intrapartum FHR (reduced FHR variability, late decelerations, and severe variable decelerations) than in those who had an uneventful labor. In prolonged pregnancies, cardiac function deteriorates in fetuses that develop a nonreassuring intrapartum FHR, and the changes in the left cardiac function correlate with changes in AFI.