Late Fetal Heart Rate Decelerations Research Articles

Fetal Heart Rate Decelerations in Women with Sleep-Disordered Breathing.

Emerging literature has shown that women with sleep-disordered breathing (SDB) have increased risk for gestational hypertension/preeclampsia and gestational diabetes. Case reports suggest an association between maternal apnea and fetal heart rate deceleration but data are lacking on how maternal sleep impacts fetal health. Since decelerations may be associated with adverse outcomes, we sought to determine whether fetal heart rate decelerations were associated with SDB. A cohort study of third trimester pregnant women with a singleton fetus was conducted. Participants underwent a home sleep test with continuous portable electronic fetal monitoring. SDB was defined as a respiratory disturbance index (RDI)≥10 events/hour. The temporality between a respiratory event and fetal heart rate decelerations was determined to be present if a deceleration occurred < 30 s after a respiratory event. Forty women were included with mean (±SD) age, BMI, and gestational age of 32.0±5.5 years, 37.1±8.0 kg/m2, and 34.6±2.4 weeks respectively. Overall, n=23 (57.5%) women had SDB. Thirty-seven late decelerations were observed in 18 women; of these, 84% were temporally associated with a respiratory event. Nine of the 18 women (50%) had SDB. Ten prolonged decelerations were observed in 6 women of which nine (90%) were temporally associated with a respiratory event. Five of the six women (83%) had an RDI≥10. These initial data suggest that, in this population, the majority of both late and prolonged fetal heart rate decelerations occur with a maternal respiratory event. Since respiratory events are characteristic of maternal SDB, this raises the possibility that SDB may influence fetal well-being.

Sawtooth fetal heart rate pattern due to in utero fetal central nervous system injury

Case reports We present 3 cases of documented central nervous system (CNS) injury with a characteristic fetal heart rate (FHR) sawtooth-like pattern. In the first case, there was category I fetal heart tracing during labor, which was followed by a sudden onset of fetal tachycardia, unstable and indeterminate baseline, and episodes of a sawtooth FHR pattern (Figure 1). The Apgar scores after a vaginal delivery were 9/9 at 1 and 5 minutes. The magnetic resonance imaging of the neonate, which was performed 48 hours postpartum because of facial twitches, showed infarction of the left cerebral hemisphere because of a middle cerebral artery occlusion/thrombosis; the approximate timing of the fetal stroke coincided with the abrupt onset of the aforementioned FHR changes in labor (Figure 2). In the second case, the patient was admitted with indeterminate FHR baseline and sawtooth FHR pattern (Figure 3). Emergent cesarean delivery was performed and the Apgar scores were 0/3/3 at 1, 5, and 10 minutes; the umbilical artery cord pH was 6.87, partial pressure of CO2 was 186, and base excess was e27.7. Immediately after birth the electroencephalogram was abnormal, and the infant received brain cooling but unfortunately died. In the third case, late FHR decelerations, indeterminate baseline, and periods of sawtooth FHR pattern were noted during the second stage of labor because of excessive uterine activity (Figure 4). The Apgar scores were 3/6 at 1 and 5 minutes, the cord pH was 6.90, partial pressure of CO2 was 73 and base excess was e19.5. A cranial ultrasound of the neonate revealed grade II intraventricular hemorrhage.

Intermittent Auscultation in Labor: Could It Be Missing Many Pathological (Late) Fetal Heart Rate Decelerations? Analytical Review and Rationale for Improvement Supported by Clinical Cases.

Intermittent auscultation (IA) of fetal heart rate (FHR) is recommended/preferred in low risk labors. Its usage even in developed countries is poised to increase because of perceived benefit of reduction in operative intervention and some disillusionment with the cardiotocography (CTG). Many national guidelines have stipulated regimes (frequency/timing) of IA based on level IV evidence. These tend to get faithfully and exactingly followed. It was observed that deliveries of many unexpectedly asphyxiated infants occurred despite rigorously performed and documented IA compliant with the guidelines. This triggered a reappraisal of the robustness of IA leading to this focused review supplemented by two anonymized cases. It concludes that the current methodology of IA may be flawed in that it poses a risk of missing many or most late (pathological) FHR decelerations, one of the foremost goals of IA. This is because many late decelerations reach their nadir before the end of the contraction. Thus the currently recommended auscultation of FHR for 60 seconds after the contraction by all national guidelines seemed to encompass their “recovery” phase and appeared to be misinterpreted as normal FHR or even as a reassuring accelerative pattern in the clinical practice. A recent recommendation of recording of the FHR as a single figure (rather than a range) does not remedy this anomaly and seems even less informative. It would be better to auscultate FHR before and after the contractions (or contraction to contraction) and take the FHR just before the contraction as the baseline FHR and interpret the FHR after contraction in the context of this baseline. This relatively simple improvement would detect most late FHR decelerations thus ameliorating the risk and significantly enhancing the patient safety.

A simulation model to study maternal hyperoxygenation during labor.

To investigate the effect of maternal hyperoxygenation on fetal oxygenation and fetal heart rate decelerations during labor, using a simulation model. Use of a mathematical model that simulates feto-maternal hemodynamics and oxygenation, designed in Matlab R2012a. Clinical and engineering departments in the Netherlands. We simulated variable and late fetal heart rate decelerations, caused by uterine contractions with a different contraction interval. We continuously recorded oxygen pressure in different feto-placental compartments and fetal heart rate, during maternal normoxia and during hyperoxygenation with 100% oxygen. Changes in oxygen pressure in the intervillous space, umbilical vein and arteries, fetal cerebral and microcirculation as well as fetal heart rate deceleration depth and duration. Maternal hyperoxygenation leads to an increase in fetal oxygenation: in the presence of variable decelerations, oxygen pressure in the intervillous space increased 9-10 mmHg and in the cerebral circulation 1-2 mmHg, depending on the contraction interval. In addition, fetal heart rate deceleration depth decreased from 45 to 20 beats per minute. In the presence of late decelerations, oxygen pressure in the intervillous space increased 7-10 mmHg and in the cerebral circulation 1-2 mmHg, depending on the contraction interval. The fetus benefited more from maternal hyperoxygenation when contraction intervals were longer. According to the simulation model, maternal hyperoxygenation leads to an increase in fetal oxygenation, especially in the presence of variable decelerations. In addition, in the presence of variable decelerations, maternal hyperoxygenation leads to amelioration of the fetal heart rate pattern.

Jarisch-Herxheimer Reaction Triggered by Group B Streptococcus Intrapartum Antibiotic Prophylaxis

The Jarisch-Herxheimer reaction is an acute systemic event that can occur during the treatment of spirochetal infections. During pregnancy, it can cause signs and symptoms in both the mother and fetus, including fever, tachycardia, uterine contractions, and fetal heart rate pattern changes. A pregnant woman with limited prenatal care presented at 34 weeks of gestation in preterm labor with possible genital herpes. She received ampicillin for group B Streptococcus prophylaxis. Subsequently, she experienced subjective fever and late fetal heart rate decelerations prompting repeat cesarean delivery. Postpartum, her genital lesions were diagnosed as secondary syphilis, and her newborn had congenital syphilis. Beta-lactam antibiotics for group B Streptococcus intrapartum prophylaxis can trigger the Jarisch-Herxhemer reaction in patients with undiagnosed syphilis resulting in unanticipated changes in maternal and fetal well-being.

Assessment of a modified four-category classification of urgency of caesarean section

SummaryA four-category urgency classification for caesarean section (CS) based on clinical definitions was introduced in 2000. However, clinical application remains inconsistent. We proposed that modification of the wording of these definitions might improve consistency of assignment of urgency. A total of 349 maternity professionals applied an urgency category to 10 hypothetical cases of CS, using either the original or a modified classification. There was a supplementary question relating to urgency category in relation to the 30 minute decision-to-delivery time standard. The commonest urgency categories applied to the cases by the respondents were: Category 1: cord prolapse, significant placental abruption, maternal cardiorespiratory distress; Category 2: late fetal heart rate decelerations, CS pre-booked to avoid vaginal delivery but woman presents in advanced labour, bleeding placenta praevia without hypovolaemia, failed instrumental delivery with no fetal compromise; Category 3: deteriorating but compensated maternal medical condition; Category 4: operation at short notice but no clinical urgency. Consistency of responses in individual cases varied from 0.92 down to 0.55. Some 66% of respondents believe that only Category 1 cases should be included in a 30 minute decision-to-delivery time standard, whereas 34% would include Category 2 as well as Category 1 in this standard. The consistency of responses did not differ between the original and modified urgency classifications. Inter-rater reliability was better when comparing the answers from obstetricians compared with anaesthetists or midwives. This study found that the proposed modifications did not improve the consistency of application, and that any changes to the current classification should not be introduced without thorough investigation.

Magnesium supplementation and perinatal hypoxia: outcome of a parallel group randomised trial in pregnancy

To determine the effects of magnesium supplementation in pregnancy on the incidence of hypoxic-ischaemic encephalopathy (HIE). A randomised double-blind placebo-controlled study. A Midwife Obstetric Unit and its two referral hospitals in Cape Town, South Africa. A group of 4494 black pregnant women of low socio-economic status. Mothers, from the time of booking until delivery, were randomised to receive two identical tablets daily, containing either 128 mg slow-release magnesium stearate or lactose sugar. Primary: The incidence of HIE. Secondary: The incidence of fetal heart rate decelerations, term Stillbirths, Low Apgar Scores, Meconium Aspiration Pneumonia. The incidence of HIE (0.9%) was considerably less than anticipated (2%). There were 22 infants in the placebo group and 15 infants in the supplemented group (P = 0.279). The difference was not significant. Secondary outcomes such as late fetal heart rate decelerations (P = 0.002) and term stillbirths (P = 0.016) were reduced significantly in the supplemented group, but this finding needs further substantiation. Magnesium supplementation did not reduce the incidence of HIE significantly, probably because the study was underpowered and compliance was relatively poor.

Acute changes of cerebral venous blood flow in growth-restricted human fetuses in response to uterine contractions.

The fetal cerebral venous circulation during acute hypoxic stress provoked by uterine contractions has not been studied previously. The aim of this study was to explore the cerebral venous circulation during an oxytocin challenge test (OCT) in intrauterine growth-restricted (IUGR) fetuses. Doppler recordings of blood flow in the vein of Galen (GV), straight sinus (SS) and transverse sinus (TS) before and during uterine contractions and relaxation were obtained at the same time as electronic fetal heart rate (FHR) monitoring in 44 term IUGR fetuses. The OCT was classified as negative (normal FHR) or positive (late FHR decelerations). Non-parametric statistics were used to test differences between OCT groups. In OCT-negative cases (n = 39), de novo pulsations occurred in the GV, and SS flow velocities increased during contractions compared with basal measurements. There were no significant differences in TS flow. Flow recordings were less often obtained from OCT-positive cases (n = 5), making comparisons with OCT-negative cases uncertain. In uncompromised IUGR fetuses an acute cerebral venous hyperperfusion develops in response to uterine contractions. Pulsations in the GV are detected but are unlikely to be an ominous sign in this situation. The more centrally located TS was less discriminating for acute cerebral venous blood flow changes.

Clinical significance of uterine artery blood flow velocity waveforms during provoked uterine contractions in high-risk pregnancy.

To determine whether, in a group of high-risk pregnancies undergoing an oxytocin challenge test (OCT), uterine artery Doppler velocimetry will identify fetuses at risk of distress during the provoked contractions. Bilateral uterine artery Doppler velocimetry was performed simultaneously with electronic fetal heart rate (FHR) recordings in 67 high-risk pregnancies subjected to an OCT. Flow velocity waveforms (FVWs) were classified according to pulsatility index (PI), presence of diastolic notching and a novel classification of FVW shapes. The OCT was classified as negative (normal) or positive (late FHR decelerations). Only OCT-negative cases were allowed a trial of vaginal delivery. Non-parametric statistical methods were used to test for differences between the OCT groups. There was no difference in prevalence of high PI or diastolic notching in OCT-positive (n = 10) and OCT-negative (n = 57) cases at basal (resting) measurements or between uterine contractions in either uterine artery (P > or = 0.3). During contractions the PI could not be used for assessment due to the biphasic shape of the FVWs, but there was no difference in distribution of FVW classes between the groups in either the placental side (P > or = 0.3) or contraplacental side (P > or = 0.6) uterine artery. No significant associations between PI or FVW class distribution and birth asphyxia or operative delivery for fetal distress in labor were found (P > or = 0.1). During uterine contractions there is no difference in uterine artery FVW pattern between OCT-positive and OCT-negative cases. Recording of uterine artery FVWs during the OCT seems to be of limited clinical relevance.

Acute increase of umbilical artery vascular flow resistance in compromised fetuses provoked by uterine contractions

Background: An impaired placental circulation is involved in the mechanism of late fetal heart rate (FHR) decelerations. Objectives: To explore umbilical artery (UA) Doppler velocimetry changes in response to uterine contractions during the oxytocin challenge test (OCT) and assess the potentially clinical value of ‘OCT Doppler velocimetry’. Methods: 111 women with pregnancy complications were subjected to an OCT with simultaneous recordings of FHR and UA pulsatility index (PI). Positive OCT cases (late FHR decelarations) were compared with negative OCT cases (normal FHR patterns). Only negative OCT cases were allowed a trial of vaginal delivery. Results: The UA PI was higher in OCT positive ( N=21) than in negative cases ( N=90) during uterine contractions and relaxations ( P<0.05), but not during basal measurements. A positive OCT, but not negative, was associated with an increase of PI during contractions and relaxations compared with basal measurements ( P<0.05). Fetal growth restriction ( N=58), operative delivery for fetal distress (ODFD) in labor ( N=10), and birth asphyxia ( N=8) were not associated with PI changes significantly different from cases without these complications. Conclusions: During uterine contractions and relaxations, but not during basal measurements, a significantly higher UA PI evolved in OCT positive cases compared with OCT negative cases. This indicates a pathophysiological mechanism disclosed only during uterine activity. Although these changes would not have been revealed by traditional Doppler velocimetry, the data suggest a limited predictive value of ‘OCT Doppler velocimetry’ on the short-term neonatal outcome.

Characteristics of Fetal Heart Rate Tracings Prior to Uterine Rupture

A worrisome fetal heart rate (FHR) tracing with variable decelerations is considered to be the commonest way in which uterine rupture presents. Late decelerations, bradycardia, or an undetectable heartbeat may ensue. Signs such as abdominal pain, vaginal bleeding, hypovolemia and shock, if they occur at all, are noted later in the course. This study attempted to identify the particular FHR patterns that develop within 2 hours before uterine rupture. Rupture was defined as a complete separation of the wall of the pregnant uterus, with or without fetal expulsion, which endangers the life of the mother and/or fetus. Asymptomatic dehiscence of a uterine scar was rejected, and all 11 eligible patients were at 28 weeks' or more gestation. The incidence of uterine rupture was 0.03%. Four patients lacked a uterine scar, whereas seven had a history of cesarean delivery. There were surgical or postoperative complications in 7 of 11 cases (64%), the commonest being infection and bleeding necessitating transfusion. Two of the patients with excessive bleeding required hysterectomy. Two of the three infected patients had postpartum endometritis, and one had pelvic cellulitis. One patient developed acute tubular necrosis and adult respiratory distress syndrome. None of the women died. All but one of the eight available FHR monitor strips (87.5%) exhibited recurrent late decelerations, and half showed bradycardia just before uterine rupture. Fetal bradycardia was consistently preceded by recurrent late decelerations. One fetus displayed prolonged decelerations, and one, fetal tachycardia preceding bradycardia. Only two tracings revealed variable decelerations. These findings, though based on a small sample, suggest that recurrent late FHR decelerations rather than variable decelerations may be a reliable early sign of impending uterine rupture.

Diagnosis and Management of Primary Aldosteronism in Pregnancy: Case Report and Review of the Literature

Primary aldosteronism rarely complicates pregnancy. We present a woman with primary aldosteronism in pregnancy associated with severe preeclampsia. A 33-year-old Japanese woman with hypertension was referred to our hospital at 25 weeks of gestation. Her blood pressure was 180/100 mmHg, and laboratory tests identified a low serum potassium level and moderate proteinuria on urinalysis. The fetus was diagnosed with growth restriction. Plasma renin activity (PRA) value was 2.2 ng/mL/h and plasma aldosterone concentration (PAC) was elevated (260 pg/mL). The patient was treated medically. At 27 weeks of gestation, we noted persistent late fetal heart rate decelerations associated with uterine contractions. Therefore, elective caesarean section was performed and she was delivered of a 698-g female. After delivery, PRA declined and PAC remained elevated. Abdominal computerized tomography scan and I131-iodochoresterol scan revealed a tumor in the left adrenal gland. Laparoscopic adrenalectomy was performed and confirmed the clinical diagnosis.

Fetal cerebral oxygenation and hemodynamics during labour measured by near‐infrared spectroscopy

The failure of modern fetal monitoring techniques to measure either oxygenation or perfusion within the fetal brain may underlie their poor specificity in the detection of intrapartum hypoxia-ischaemia. We have adapted the technique of near-infrared spectroscopy (NIRS) to obtain continuous, quantified measurements of changes in human fetal cerebral oxygenation and blood volume during labour. More than 140 fetuses have been studied at University College London for periods ranging from 10 to 765 minutes. Reciprocal changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin, indicating changing cerebral haemoglobin saturation, have been observed during uterine hyperstimulation with oxytocin, administration of maternal oxygen, changing maternal posture, and late fetal heart rate decelerations. Uterine contraction frequency greater than 1 every 2 minutes was associated with a fall in fetal cerebral oxygenation. A method for quantifying the oxygen saturation of hemoglobin derived from all vascular compartments (SmcO2) is described. There was a significant positive correlation between SmcO2 and umbilical artery pH. Conversely, the base deficit of blood from the umbilical artery showed a negative correlation with SmcO2. Changes in optical pathlength due to probe movement during uterine contractions are a potential source of error in the measurements. Preliminary data obtained using intensity modulated optical spectrometry, a technique that continuously measures optical pathlength, suggest that the maximum contribution of movement artifact to observed changes in chromophore concentration is 12%. These preliminary data demonstrate that NIRS is capable of measuring fetal cerebral oxygenation and blood volume during labour. However, because none of the fetuses in this study was born with evidence of intrapartum hypoxia-ischaemia, we cannot comment on the value of NIRS as a means of intrapartum surveillance. Further developments, including the routine use of IMOS and rigorous testing by randomized trials, will be required before this question is answered. MRDD Research Reviews 3:59–68, 1997. © 1997 Wiley-Liss, Inc.

Fetal cerebral oxygenation and hemodynamics during labour measured by near-infrared spectroscopy

The failure of modern fetal monitoring techniques to measure either oxygenation or perfusion within the fetal brain may underlie their poor specificity in the detection of intrapartum hypoxia-ischaemia. We have adapted the technique of near-infrared spectroscopy (NIRS) to obtain continuous, quantified measurements of changes in human fetal cerebral oxygenation and blood volume during labour. More than 140 fetuses have been studied at University College London for periods ranging from 10 to 765 minutes. Reciprocal changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin, indicating changing cerebral haemoglobin saturation, have been observed during uterine hyperstimulation with oxytocin, administration of maternal oxygen, changing maternal posture, and late fetal heart rate decelerations. Uterine contraction frequency greater than 1 every 2 minutes was associated with a fall in fetal cerebral oxygenation. A method for quantifying the oxygen saturation of hemoglobin derived from all vascular compartments (SmcO2) is described. There was a significant positive correlation between SmcO2 and umbilical artery pH. Conversely, the base deficit of blood from the umbilical artery showed a negative correlation with SmcO2. Changes in optical pathlength due to probe movement during uterine contractions are a potential source of error in the measurements. Preliminary data obtained using intensity modulated optical spectrometry, a technique that continuously measures optical pathlength, suggest that the maximum contribution of movement artifact to observed changes in chromophore concentration is 12%. These preliminary data demonstrate that NIRS is capable of measuring fetal cerebral oxygenation and blood volume during labour. However, because none of the fetuses in this study was born with evidence of intrapartum hypoxia-ischaemia, we cannot comment on the value of NIRS as a means of intrapartum surveillance. Further developments, including the routine use of IMOS and rigorous testing by randomized trials, will be required before this question is answered. MRDD Research Reviews 3:59–68, 1997. © 1997 Wiley-Liss, Inc.

Effects of intracervical prostaglandin E 2 on fetal heart rate and uterine activity patterns in the presence of oligohydramnios

OBJECTIVE: Our purpose was to compare fetal heart rate patterns and uterine activity before and after preincubation prostaglandin E 2 administration in the presence or absence of oligohydramnios. STUDY DESIGN: In a retrospective case-controlled review we examined cases in which prostaglandin E 2 (Prepidil) was inserted intracervically for gravid women requring an induction of labor in the presence of either oligohydramnios (amniotic fluid index ≤5.0) or adequate fluid (amniotic fluid index 5.1 to 23.9). Uterine activity and fetal heart rate tracings that were begun 1 hour before and continued for 6 hours after dosing were interpreted without knowledge of amniotic fluid volume. RESULTS: Cases in the olgiohydramnios ( n = 51) and adequate fluid ( n = 49) groups were the same for maternal age, race, parity, gestational age, and predose Bishop score. Patients with oligohydramnios had more high-amplitude contractions in the first hour after dosing (9.0 ± 1.2 vs 6.1 ± 0.9, p < 0.05), but there were no significant differences in the frequency or duration of contractions during the subsequent 5 hours. Uterine hyperstimulation was not seen, and there were no differences in the frequency of variable or late fetal heart rate decelerations. CONCLUSION: For pregnancies undergoing preinduction cervical ripening with intracervical prostaglandin E 2, the presence of oligohydramnios was not associated with a greater risk of fetal heart rate decelerations, although contractions were more common during the first hour after dosing.

Late Fetal Heart Decelerations and Changes in Cerebral Oxygenation During the First Stage of Labour

Objective To test the hypothesis that late fetal heart rate decelerations are associated with a decrease in cerebral oxygenation.Design Changes in fetal cerebral concentrations of oxyhaemoglobin and deoxyhaemoglobin were measured by near infrared spectroscopy, before, during and after contractions with late fetal heart rate decelerations and compared with changes during contractions with no alteration of heart rate.Setting Teaching hospital obstetric unit.Subjects Ten women in labour at term.Results The changes in fetal cerebral oxyhaemoglobin and deoxyhaemoglobin concentrations that occurred during contractions were quantitatively similar, irrespective of the fetal heart rate changes. However, late fetal heart rate decelerations were associated with a significantly greater fall, after the uterine contraction, in the mean concentration of fetal cerebral oxyhaemoglobin of 0.52 mu mol/100 g (SD 0.25) (P < 0.001) and a significantly greater rise in the mean concentration of deoxyhaemoglobin of 0.36 mu mol/100 g (SD 0.35) (P < 0.01).Conclusion Late fetal heart rate decelerations are associated with a significant decrease in cerebral oxygenation.

Late fetal heart decelerations and changes in cerebral oxygenation during the first stage of labour.

To test the hypothesis that late fetal heart rate decelerations are associated with a decrease in cerebral oxygenation. Changes in fetal cerebral concentrations of oxyhaemoglobin and deoxyhaemoglobin were measured by near infrared spectroscopy, before, during and after contractions with late fetal heart rate decelerations and compared with changes during contractions with no alteration of heart rate. Teaching hospital obstetric unit. Ten women in labour at term. The changes in fetal cerebral oxyhaemoglobin and deoxyhaemoglobin concentrations that occurred during contractions were quantitatively similar, irrespective of the fetal heart rate changes. However, late fetal heart rate decelerations were associated with a significantly greater fall, after the uterine contraction, in the mean concentration of fetal cerebral oxyhaemoglobin of 0.52 mumol/100 g (SD 0.25) (P < 0.001) and a significantly greater rise in the mean concentration of deoxyhaemoglobin of 0.36 mumol/100 g (SD 0.35) (P < 0.01). Late fetal heart rate decelerations are associated with a significant decrease in cerebral oxygenation.

Increases in human fetal hemoglobin oxygen saturation during late fetal heart rate decelerations as a response to intrauterine stress: [formula omitted], C. Harvey x, G. Anderson, T. Shailer x, L. Troyer. Dept. of OB/GYN, The University of Texas Medical Branch, Galveston, TX

Increases in human fetal hemoglobin oxygen saturation during late fetal heart rate decelerations as a response to intrauterine stress: [formula omitted], C. Harvey x, G. Anderson, T. Shailer x, L. Troyer. Dept. of OB/GYN, The University of Texas Medical Branch, Galveston, TX

Fetal heart rate decelerations and umbilical cord blood gas values

Although fetal heart rate (FHR) monitoring is widely used for fetal surveillance, there is still disagreement about the value of cardiotocography and the interpretation of FHR patterns. We addressed this in a prospective study in which umbilical cord blood gas and pH values at the time of cesarean section were related to different FHR patterns classified prior to surgery. The patient population consisted of 56 pregnant women with singleton fetuses of gestational age between 37 and 43 weeks. Indication for cesarean section was late FHR decelerations in 16 cases and variable decelerations in 17. Twenty-three patients operated on electively, and without any FHR abnormalities, served as a reference group. Late FHR decelerations were associated with the lowest pH and Po 2 levels in arterial as well as in venous blood. In the group with variable decelerations, the umbilical vein Po 2 was similar to that of the reference group, whereas the Po 2 value in the artery was significantly lower. Hence, in this clinical study a clear relationship was found between the different FHR patterns and changes in the acid-base balance.

Doppler velocimetry in twin pregnancy

The flow velocity waveform profile in the umbilical artery was measured in 50 pairs of twins during the last week before birth. A significant association was found between high resistance indicies and occurrence of late fetal heart rate decelerations; the higher the resistance, the more frequent the decelerations. Further, the connection between high resistance in the circulation of the umbilical artery and low birth weight was confirmed. Flow velocity measurements in the umbilical artery seem to be a valuable tool in identifying twin fetuses suffering from placental insufficiency.