Understanding fetal physiology and second line monitoring during labor

Fetal monitoring technologies for the detection of intrapartum hypoxia - challenges and opportunities

Intrapartum fetal hypoxia is related to long-term morbidity and mortality of the fetus and the mother. Fetal surveillance is extremely important to minimize the adverse outcomes arising from fetal hypoxia during labour. Several methods have been used in current clinical practice to monitor fetal well-being. For instance, biophysical technologies including cardiotocography, ST-analysis adjunct to cardiotocography, and Doppler ultrasound are used for intrapartum fetal monitoring. However, these technologies result in a high false-positive rate and increased obstetric interventions during labour. Alternatively, biochemical-based technologies including fetal scalp blood sampling and fetal pulse oximetry are used to identify metabolic acidosis and oxygen deprivation resulting from fetal hypoxia. These technologies neither improve clinical outcomes nor reduce unnecessary interventions during labour. Also, there is a need to link the physiological changes during fetal hypoxia to fetal monitoring technologies. The objective of this article is to assess the clinical background of fetal hypoxia and to review existing monitoring technologies for the detection and monitoring of fetal hypoxia. A comprehensive review has been made to predict fetal hypoxia using computational and machine-learning algorithms. The detection of more specific biomarkers or new sensing technologies is also reviewed which may help in the enhancement of the reliability of continuous fetal monitoring and may result in the accurate detection of intrapartum fetal hypoxia.

Pathophysiological interpretation of fetal heart rate tracings in clinical practice

The onset of regular, strong, and progressive uterine contractions may result in both mechanical (compression of the fetal head and/or umbilical cord) and hypoxic (repetitive and sustained compression of the umbilical cord or reduction in uteroplacental oxygenation) stresses to a human fetus. Most fetuses are able to mount effective compensatory responses to avoid hypoxic-ischemic encephalopathy and perinatal death secondary to the onset of anaerobic metabolism within the myocardium, culminating in myocardial lactic acidosis. In addition, the presence of fetal hemoglobin, which has a higher affinity for oxygen even at low partial pressures of oxygen than the adult hemoglobin, especially increased amounts of fetal hemoglobin (ie, 180-220 g/L in fetuses vs 110-140 g/L in adults), helps the fetus to withstand hypoxic stresses during labor. Different national and international guidelines are currently being used for intrapartum fetal heart rate interpretation. These traditional classification systems for fetal heart rate interpretation during labor are based on grouping certain features of fetal heart rate (ie, baseline fetal heart rate, baseline variability, accelerations, and decelerations) into different categories (eg, category I, II, and III tracings, "normal, suspicious, and pathologic" or "normal, intermediary, and abnormal"). These guidelines differ from each other because of the features included within different categories and because of their arbitrary time limits stipulated for each feature to warrant an obstetrical intervention. This approach fails to individualize care because the "ranges of normality" for stipulated parameters apply to the population of human fetuses and not to the individual fetus in question. Moreover, different fetuses have different reserves and compensatory responses and different intrauterine environments (presence of meconium staining of amniotic fluid, intrauterine inflammation, and the nature of uterine activity). Pathophysiological interpretation of fetal heart rate tracing is based on the application of the knowledge of fetal responses to intrapartum mechanical and/or hypoxic stress in clinical practice. Both experimental animal studies and observational human studies suggest that, just like adults undertaking a treadmill exercise, human fetuses show predictable compensatory responses to a progressively evolving intrapartum hypoxic stress. These responses include the onset of decelerations to reduce myocardial workload and preserve aerobic metabolism, loss of accelerations to abolish nonessential somatic body movements, and catecholamine-mediated increases in the baseline fetal heart rate and effective redistribution and centralization to protect the fetal central organs (ie, the heart, brain, and adrenal glands), which are essential for intrauterine survival. Moreover, it is essential to incorporate the clinical context (progress of labor, fetal size and reserves, presence of meconium staining of amniotic fluid and intrauterine inflammation, and fetal anemia) and understand the features suggestive of fetal compromise in nonhypoxic pathways (eg, chorioamnionitis and fetomaternal hemorrhage). It is important to appreciate that the timely recognition of the speed of onset of intrapartum hypoxia (ie, acute, subacute, and gradually evolving) and preexisting uteroplacental insufficiency (ie, chronic hypoxia) on fetal heart rate tracing is crucial to improve perinatal outcomes.

Types of intrapartum hypoxia in the newborn at term with metabolic acidemia: A retrospective study

INTRODUCTION

In the most recent recommendations of the International Federation of Gynecology and Obstetrics (FIGO), a chapter was dedicated to the physiological approach and to the description of fetal mechanisms developed to respond to hypoxia. Our objective was to classify the type of hypoxia in the case of metabolic acidemia and to describe the order of appearance of fetal heart rate abnormalities in cases of gradually evolving hypoxia.

MATERIAL AND METHODS

132 neonates born between 2018 and 2020 with acidemia were included. We excluded preterm birth, fetuses with congenital anomaly and twin pregnancies. Intrapartum cardiotocography traces were assigned to one of these four types of labor hypoxia: acute, subacute, gradually evolving and chronic hypoxia. For gradually evolving hypoxia, fetal heart rate abnormalities were described according to the FIGO classification.

RESULTS

36 cardiotocography traces (27.3%) were classified as acute hypoxia, 14 (10.6%) as subacute hypoxia, and 3 (3.2%) as chronic hypoxia; gradually evolving hypoxia occurred in 62 cases (47%). In 77.4% of cases of gradually evolving hypoxia, deceleration was the first anomaly to appear, with loss of variability and bradycardia appearing later. Increased fetal heart rate was observed immediately after late deceleration in 46.8% of cases and was followed by a loss of variability or saltatory rhythm in 37.1% of cases.

CONCLUSIONS

In cases of metabolic acidemia at term, the most frequent situation observed was gradually evolving hypoxia, with an initial occurrence of decelerations. The sequence of fetal heart rate modifications was variable.

Increased variability of fetal heart rate during labour: a review of preclinical and clinical studies

Increased fetal heart rate variability (FHRV) in intrapartum cardiotocographic recording has been variably defined and poorly understood, limiting its clinical utility. Both preclinical (animal) and clinical (human) evidence support that increased FHRV is observed in the early stage of intrapartum fetal hypoxaemia but can also be observed in a subset of fetuses during the preterminal stage of repeated hypoxaemia. This review of available evidence provides data and expert opinion on the pathophysiology of increased FHRV, its clinical significance and a stepwise approach regarding the management of this pattern, and propose recommendations for standardisation of related terminology.

AACC Guidance Document on the Use of Point-of-Care Testing in Fertility and Reproduction

Background

The AACC Academy revised the reproductive testing section of the Laboratory Medicine Practice Guidelines: Evidence-Based Practice for Point-of-Care Testing (POCT) published in 2007.

Methods

A panel of Academy members with expertise in POCT and laboratory medicine was formed to develop guidance for the use of POCT in reproductive health, specifically ovulation, pregnancy, premature rupture of membranes (PROM), and high-risk deliveries. The committee was supplemented with clinicians having Emergency Medicine and Obstetrics/Gynecology training.

Results

Key recommendations include the following. First, urine luteinizing hormone (LH) tests are accurate and reliable predictors of ovulation. Studies have shown that the use of ovulation predicting kits may improve the likelihood of conception among healthy fertile women seeking pregnancy. Urinary LH point-of-care testing demonstrates a comparable performance among other ovulation monitoring methods for timing intrauterine insemination and confirming sufficient ovulation induction before oocyte retrieval during in vitro fertilization. Second, pregnancy POCT should be considered in clinical situations where rapid diagnosis of pregnancy is needed for treatment decisions, and laboratory analysis cannot meet the required turnaround time. Third, PROM testing using commercial kits alone is not recommended without clinical signs of rupture of membranes, such as leakage of amniotic fluid from the cervical opening. Finally, fetal scalp lactate is used more than fetal scalp pH for fetal acidosis due to higher success rate and low volume of sample required.

Conclusions

This revision of the AACC Academy POCT guidelines provides recommendations for best practice use of POCT in fertility and reproduction.

Heart rate markers for prediction of fetal acidosis in an experimental study on fetal sheep

To overcome the difficulties in interpreting fetal heart rate (FHR), several tools based on the autonomic nervous system and heart rate variability (HRV) have been developed. The objective of this study was to use FHR and HRV parameters for the prediction of fetal hypoxia. It was an experimental study in the instrumented fetal sheep. Repeated umbilical cord occlusions were performed to achieve severe acidosis. Hemodynamic parameters, ECG, and blood gases were analyzed. The variables used were heart rate baseline, HRV analysis (RMSSD, SDNN, LF, HF, HFnu, Fetal Stress Index (FSI), …), and morphological analysis of decelerations. The gold standard used to classify hypoxia was the fetal arterial pH (pH < 7.10). Different multivariable statistical methods (logistic regression and decision trees) were applied for the detection of acidosis. 21 lambs were instrumented. A total of 130 pairs of FHR/fetal pH analysis were obtained of which 29 in the acidosis group and 101 in the non-acidosis group. After logistic regression model with bootstrap resampling and stepwise backward selection, only one variable was selected, FSI. The AUC of FSI alone in this model was 0.81 with a sensitivity of 0.66, specificity of 0.88, PPV of 0.61, and NPV of 0.90 considering a threshold of 68. Decision trees with CHAID and CART algorithms showed a sensitivity of 0.48 and 0.59, respectively, and a specificity of 0.94 for both. All employed methods identified HRV variables as the most predictive of acidosis. The primary variables selected automatically were those from the HRV. Supporting the use of FHRV measures for the screening of fetal acidosis during labour is interesting.

Roles of parasympathetic outflow and sympathetic outflow in the cardiovascular response to brief umbilical cord occlusion in fetal sheep

Fetal heart rate (FHR) deceleration is the most common change seen during labor. The role of the autonomic nervous system in regulating the fetal cardiovascular response during multiple uterine contractions has been well-established. However, the mechanism underlying the hemodynamic response remains unclear and the specific reflex that mediates the cardiovascular modifications is still controversial. This study aimed to determine the role of the sympathetic and parasympathetic systems on fetal hemodynamics in complete cord occlusion. Chronically instrumented fetal sheep were randomized to receive an intravenous injection of atropine 2.5 mg (n = 8), propranolol 5 mg (n = 7), atropine and propranolol (n = 7), or a control protocol (n = 9), followed by three episodes of 1-minute umbilical cord occlusion repeated every 5 minutes. Cord compression induces a rapid decrease in the FHR and a rapid increase in MAP. The decrease in FHR is caused by an increase in parasympathetic activity, (atropine and atropine-propranolol abolish the FHR response to the occlusion). The change in FHR during occlusion was not modified by propranolol injection, showing no effect of sympathetic tone. The increase in MAP during occlusion was similar in the four protocols. After releasing occlusion, the FHR was still lower than that at baseline due to a sustained parasympathetic tone. Suppression of the parasympathetic output to the cardiovascular system unmasks an increase in the FHR above baseline values. The lower FHR with the propranolol protocol further supports an increase in myocardial β-adrenoceptor stimulation after cord release. The increase in MAP after cord release was similar in the four protocols, except after the early stage of interocclusion period in atropine protocol. Four minutes after cord release, the FHR returned to baseline irrespective of the drugs that were infused, thereby showing recovery of ANS control. Blood gases (pH, PaCO2, PaO2) and plasma lactate concentrations was similar between the four protocols at the end of three applications of UCO. Complete cord compression-induced deceleration is likely due to acute activation of parasympathetic output. β-adrenoceptor activity is involved in the increase in FHR after cord release. Understanding the reflexes involved in FHR deceleration may help us understand the mechanisms underlying fetal autonomic adaptation during cord occlusion.

Changes in S100B and troponin levels in a fetal sheep model of worsening acidosis

BACKGROUND

S100B and cardiac troponin T (c-TnT) are relevant biomarkers at birth of hypoxic-ischemic encephalopathy (HIE) and myocardial ischemia secondary to metabolic acidosis during labor, respectively. The purpose was to assess in-utero changes in S100B and c-TnT levels in an experimental model of labor-like acidosis.

METHODS

Repeated umbilical cord occlusions (UCOs) in ten experiments were performed in mild (phase A, 1 UCO/5 mn), moderate (phase B, 1 UCO/3 mn), and severe (phase C, 1 UCO/2 mn) period. The experiments were stopped if arterial pH reached 6.90.

RESULTS

UCOs resulted in fetal acidosis with pH dropping to 6.99 ±0.13. When compared to the baseline period fetal S100B increased between phases A and B (7% ± 4 vs 17% ± 13, p = 0.030) and between phases A and C (7% ± 4 vs 24% ± 8, p < 0.001). Fetal c-TnT serum levels increased during occlusions: 102 ng/L (58-119) in phase A, vs 119 ng/L (103-198) in phase B vs 169 ng / L (128-268) in phase C (p < 0.05, for all). When compared to the baseline control period, fetal ΔcTnT was significantly modified throughout UCO series: 5.0% (-3; 45) in phase A, 51% (4; 263) in phase B, and 77% (56.5; 269) in phase C (p < 0.05 for all).

CONCLUSIONS

S100B and c-TnT increased when fetal acidosis occurred, which reflects the potential neurological damage and fetal cardiovascular adaptation.

Evaluation and impact of fetal physiology training on fetal heart rate analysis

INTRODUCTION

Evaluation of fetal well-being during labor is based on fetal heart rate (FHR) analysis, which requires physiology expertise. The aim of the present study was to assess medical residents' fetal physiology training in terms of theoretical knowledge, FHR interpretation, and use of second-line examinations.

METHODS

This single-center, prospective study of obstetrics and gynecology residents (N = 34) at CHU de Lille Hospital (Lille, France) was conducted from November 2017 to November 2018. Evaluation and training were conducted in three stages. First, residents' pre-training knowledge of FHR interpretation and use of fetal scalp blood sampling (FBS) was assessed using clinical cases. Second, a didactic training session on fetal physiology was delivered. Finally, post-training knowledge was evaluated using the same cases presented during pre-training. I: Pre-training, 3%, 11.8%, and 14.7% of residents considered their training on fetal physiology, FHR analysis, and second-line examinations, respectively, to be sufficient. Training significantly improved their theoretical knowledge, which was assessed using multiple-choice questions (median [interquartile range]: 1.5 [1.0-2.0] vs. 4.0 [3.0-4.5], p<0.001), and reduced the number of FBS requested (36.3% vs. 29.5%, p = 0.002). Krippendorff's alpha coefficient for the reproducibility of residents' responses improved significantly, reflecting greater homogenization of clinical practice decisions (alpha [95% confidence interval]: 0.60 [0.55-0.65] vs. 0.72 [0.67-0.76]).

CONCLUSION

Improved fetal physiology knowledge promotes more accurate FHR interpretation, better indications for second-line examinations, and greater homogenization of clinical practice decisions. Future studies should evaluate the impact of fetal physiology training on clinical practice.

Total intrapartum fetal reperfusion time (fetal resilience) and neonatal acidemia

OBJECTIVE

The main objective is to study the predictive capacity of intrapartum total fetal reperfusion (fetal resilience) by itself or in combination with other parameters as a predictor of neonatal acidemia.

STUDY DESIGN

A retrospective case-control study was carried out at the Miguel Servet University Hospital (Zaragoza, Spain) on a cohort of 5694 pregnant women between June 2017 and October 2018. Maternal, perinatal, and cardiotocographic records were collected. Two reviewers blindly described the monitors with the American College of Obstetricians and Gynecologists (ACOG) categorizations and parameters and the non-ACOG parameters. Neonatal acidemia was defined as pH <7.10. The parameters analyzed to predict acidemia were evaluated using the sensitivity for specificity 90% value, and the area under the receiver operating characteristic curve.

RESULTS

We recorded 192 infants with acidemia, corresponding to a global acidemia rate of 3.4%. Of these, 72 were excluded for lack of criteria, leaving 120 patients with arterial acidemia included in the study and 258 in the control group. The sensitivity (specificity 90%) of detection of acidemia was 42% for the ACOG III categorization (AUC, 0.524: 95% CI, 0.470-0.578), 24% for fetal reperfusion (AUC, 0.704: 95% CI, 0.649-0.759), 27% for total area of decelerations (AUC, 0.717: 95% CI, 0.664-0.771) and 50% for the multivariate model built from total reperfusion time (AUC, 0.826: 95% CI, 0.783-0.869). The total reperfusion time corresponding to a false negative rate of 10% is 23.75 min, with 28% of fetuses above this time. The AUC and sensitivity for a false negative rate of 10% are equivalent for deceleration area and time of reperfusion (p = .504).

CONCLUSION

The total reperfusion time (fetal resilience) and total deceleration area are non-ACOG parameters with a good predictive ability for neonatal acidemia, higher than the ACOG III classification and without statistical differences between them. The discrimination ability of total reperfusion time can be improved using a multivariate model. As a cutoff for its use we suggest 23.75 min in 30 min corresponding to an acidemic classification rate of 90%. New parameters in combination with other maternal, obstetrics, or fetal variables, are required for the interpretation of fetal well-being.

Systematic Review of Intrapartum Fetal Heart Rate Spectral Analysis and an Application in the Detection of Fetal Acidemia

It is fundamental to diagnose fetal acidemia as early as possible, allowing adequate obstetrical interventions to prevent brain damage or perinatal death. The visual analysis of cardiotocography traces has been complemented by computerized methods in order to overcome some of its limitations in the screening of fetal hypoxia/acidemia. Spectral analysis has been proposed by several studies exploring fetal heart rate recordings while referring to a great variety of frequency bands for integrating the power spectrum. In this paper, the main goal was to systematically review the spectral bands reported in intrapartum fetal heart rate studies and to evaluate their performance in detecting fetal acidemia/hypoxia. A total of 176 articles were reviewed, from MEDLINE, and 26 were included for the extraction of frequency bands and other relevant methodological information. An open-access fetal heart rate database was used, with recordings of the last half an hour of labor of 246 fetuses. Four different umbilical artery pH cutoffs were considered for fetuses' classification into acidemic or non-acidemic: 7.05, 7.10, 7.15, and 7.20. The area under the receiver operating characteristic curve (AUROC) was used to quantify the frequency bands' ability to distinguish acidemic fetuses. Bands referring to low frequencies, mainly associated with neural sympathetic activity, were the best at detecting acidemic fetuses, with the more severe definition (pH ≤ 7.05) attaining the highest values for the AUROC. This study shows that the power spectrum analysis of the fetal heart rate is a simple and powerful tool that may become an adjunctive method to CTG, helping healthcare professionals to accurately identify fetuses at risk of intrapartum hypoxia and to implement timely obstetrical interventions to reduce the incidence of related adverse perinatal outcomes.

Fetal physiology cardiotocography training, a regional evaluation

INTRODUCTION

Cardiotocography (CTG) has its limits in detecting fetal acidosis and intrapartum asphyxia. Our aim was to evaluate a CTG training programme based on fetal physiology in the Mediterranean perinatal network.

METHODS

Professionals from 41 maternity units of the Mediterranean network were invited to participate in a CTG masterclass based on fetal physiology in March 2019 and October 2019. They were asked to react to three practical cases by a physiological approach before the training course (T0), one month after (T1) and six to seven months after (T2). The mean scores were compared by using a mixed model including lapse of time to evaluation, profession of participants and level of the maternity unit as fixed effects.

RESULTS

A total of 248 professionals from 32 maternity units finally participated in the organizational audit. By using a mixed model, we found a significant improvement of the mean score at T1=6.44/10 compared to T0=4.97/10 (p<0.0001), and a significant improvement of the mean score obtained at T2=6.17/10 compared to T0 (p<0.0001). T2 scores were not significantly different from T1 scores (p=0.143).

DISCUSSION

A CTG training programme based on fetal physiology showed a significant improvement in the professionals' interpretation of CTG at short term and stable results at long term. Continuing medical education could help maintain and improve knowledge to ensure neonatal safety.

Umbilical cord arterial and venous gases, ionogram, and glucose level for predicting neonatal morbidity at term

OBJECTIVE

To determine which parameter of umbilical arterial cord gas analysis, pH, base deficit, lactate concentration, ionogram values, or glucose level index is the best predictor of neonatal morbidity at term.

DESIGN

We conducted a 15-month retrospective cohort study that included all nonanomalous, singleton, term births at a single center. The predictive ability of lactate concentration, base deficit, pH, ionogram values, and glucose level were compared using receiver-operating characteristic curves for global and neurological composite morbidity. Optimal cutoff values for lactate concentration, base deficit, and pH were estimated based on their maximum area under the curve.

RESULTS

We included 5161 newborns: 52 (1.01 %) had global composite morbidity, and 17 had (0.33 %) neurological composite morbidity. Blood levels of potassium, calcium, natremia, glucose level, and HCO₃^- did not differ significantly between groups. pH, partial pressure of CO₂, partial pressure of O₂, base deficit, and lactate levels differed significantly between neonates in the groups with and without global composite morbidity. Nearly similar results were found for neurological composite morbidity. The predictive ability did not differ between arterial pH and arterial lactate concentration (P = .25) and base deficit (P = .79). Optimal cutoff values to predict global composite morbidity were arterial pH 7.144, venous pH 7.236, and arterial lactate concentration 6.5 mmol/L.

CONCLUSIONS

Acid-base status analysis remains the best objective indicator for predicting neonatal morbidity and can be estimated using pH, lactate, or base deficit. Ionogram cord blood composition and glucose level do not appear to be useful for this purpose.

Autonomic response to fetal acidosis using an experimental sheep model

BACKGROUND

The autonomic nervous system has a major role in fetal adaptation to hypoxia. Its activity might be assessed using heart rate variability and heart rate deceleration analyses.

OBJECTIVE

To evaluate the ability of different heart rate variability and morphological deceleration analyses to predict fetal acidosis during labor in an experimental fetal sheep model.

STUDY DESIGN

Repeated 1-minute total umbilical cord occlusions were performed at mild (1minute every 5 min), moderate (1 min every 3 min), and severe (1 min every 2 min) umbilical cord occlusion periodicities until arterial pH reached 7.10. Hemodynamic,blood gas analysis, morphological analysis of decelerations (magnitude, slope, and area ofdecelerations), and heart rate variability parameters were recorded throughout the experiment.Heart rate variability analysis included temporal analysis (root mean square of successivedifferences between adjacent RR intervals, standard deviation of normal to normal RR intervals, short term variability), spectral analysis (low frequencies, high frequencies,normalized high frequencies), and a new index developed by our team, the Fetal Stress Index.We defined and compared three pH groups: >7.20, 7.10-7.20, and <7.10.

RESULTS

Eleven experiments were performed. Repetitive umbilical cord occlusions resulted in progressive fetal acidosis. Fetal Stress Index was correlated with pH and lactate (p < 0.05) and increased with acidosis. There were no significant correlations between pH, lactate, and other indices (spectral analysis, temporal analysis, or morphological analysis of decelerations).

CONCLUSION

This protocol allowed us to identify the progressive onset of fetal acidosis in an experimental model close to labor. Fetal Stress Index is a heart rate variability method that varies with acidosis and indicates an increase in parasympathetic nervous system activity in response to fetal acidosis.

Independent Analysis of Decelerations and Resting Periods through CEEMDAN and Spectral-Based Feature Extraction Improves Cardiotocographic Assessment

Fetal monitoring is commonly based on the joint recording of the fetal heart rate (FHR) and uterine contraction signals obtained with a cardiotocograph (CTG). Unfortunately, CTG analysis is difficult, and the interpretation problems are mainly associated with the analysis of FHR decelerations. From that perspective, several approaches have been proposed to improve its analysis; however, the results obtained are not satisfactory enough for their implementation in clinical practice. Current clinical research indicates that a correct CTG assessment requires a good understanding of the fetal compensatory mechanisms. In previous works, we have shown that the complete ensemble empirical mode decomposition with adaptive noise, in combination with time-varying autoregressive modeling, may be useful for the analysis of those characteristics. In this work, based on this methodology, we propose to analyze the FHR deceleration episodes separately. The main hypothesis is that the proposed feature extraction strategy applied separately to the complete signal, deceleration episodes, and resting periods (between contractions), improves the CTG classification performance compared with the analysis of only the complete signal. Results reveal that by considering the complete signal, the classification performance achieved 81.7% quality. Then, including information extracted from resting periods, it improved to 83.2%.

Physiological CTG interpretation: the significance of baseline fetal heart rate changes after the onset of decelerations and associated perinatal outcomes

OBJECTIVE

To determine the perinatal outcomes in fetuses with baseline fetal heart rate changes with preceding decelerations on the cardiotocography (CTG) trace, and to interpret CTG traces from the aspect of fetal physiology.

MATERIALS AND METHODS

A retrospective analysis of 500 consecutive CTG traces was carried out. The presence of repetitive variable and late decelerations followed by the changes in the baseline including baseline tachycardia and abnormal baseline variability were determined. Perinatal outcomes including Apgar scores and umbilical arterial pH at birth, NNU admission, and meconium-stained amniotic fluid were analyzed. We interpreted the changes in CTG based on fetal physiology.

RESULTS

When repetitive variable and late decelerations were present without tachycardia (n = 81), none of the fetuses had an Apgar score <7 at 5 minutes or an umbilical cord pH <7. After the onset of fetal tachycardia (n = 262), fetuses showed decreased Apgar scores and umbilical arterial pH(p < .01), however, there was no significant difference in the rate of abnormal 5 min Apgar score, abnormal PH and NNU admission, if the baseline variability remained normal. However, if the baseline variability was abnormal (n = 44), (either increased or reduced) after tachycardia, there was a statistically significant increase in poor perinatal outcomes. Fetuses with abnormal versus normal variability had lower Apgar scores ≤7 at 5 min (29.6 versus 0.9%, p = .000); umbilical cord arterial pH <7 at birth (29.5 versus 0%, p = .000); increased admission to the NNU (27.3 versus 3.7%, p = .000) and increased incidence of meconium-stained amniotic fluid (38.6 versus 22.5%, p = .024). These serial changes in CTG could be interpreted and predicted by the application of fetal physiology.

CONCLUSIONS

There were significant differences in perinatal outcomes when fetuses were exposed to evolving intrapartum hypoxic stress culminating in an abnormal baseline fetal heart rate variability, which was preceded by repetitive decelerations, followed by an increase in the baseline heart rate. However, despite ongoing decelerations, if the baseline variability remained normal, none of the fetuses had a pH of <7. Therefore, the knowledge of fetal physiological response to evolving hypoxic stress can be reliably used to determine fetal compensation.

Maternal health care wearing equipment based on fetal information monitoring

In order to monitor the fetal information in real time and ensure the health of the pregnant women themselves and their fetuses during pregnancy, a kind of health wearing equipment, abdominal care belt is designed in this study, which can be worn by pregnant women and can be monitored by modern mobile medical APP, and verifies the related performance of the design through a series of experiments. The results show that the safety, practicability and aesthetics of the abdominal care belt designed in this study are all up to the standard. Therefore, the abdominal care belt designed in this study is a relatively successful product, which is expected to be applied in the future and enter the market, so that pregnant women during pregnancy can be more relaxed and convenient.

Caffeine administered to pregnant sows improves piglet vitality, gas exchange and body weight gain

Intra-partum asphyxia is the most common non-infectious etiology limiting the performance of neonate piglets. Previous studies indicate caffeine (orally and subcutaneously) reverses the effects of intra-partum asphyxia in neonate piglets. In this study, there was investigation of whether use of a novel therapeutic protocol for administering caffeine subcutaneously to pregnant sows would improve the newborn piglets' vitality, physio-metabolic profiles and body weight gain. Sows were randomly divided into two groups (n = 10 each). Caffeine or NaCl 0.9% was administered 2 days pre-farrowing. Physio-metabolic profiles were measured using blood from the anterior vena cava. The vitality of piglets was evaluated immediately after birth. Piglets (n = 180) were weighed at birth and on days 7, 14 and 21 of lactation. Caffeine positively affected the vitality of the piglets, as indicated by greater vitality scores than that for the control group (8.72 ± 0.12 compared with 7.28 ± 0.16, P < 0.001). Metabolic values were similar between groups, but pO₂ values were greater in the piglets with greater vitality scores treated with caffeine (19.10 ± 0.82 compared with 14.49 ± 1.42, P < 0.01), indicating increased respiratory rates. Body weight gain at day 21 was greater in the piglets treated with caffeine that had greater vitality scores than the control piglets having greater vitality scores (6.87 ± 0.18 compared with 6.52 ± 0.25 kg, P < 0.05). Caffeine administration before birth improves the vitality and respiratory capacity of piglets, increasing their adaptation to extra-uterine environment.

Intrapartum Fetal Heart Rate: A Possible Predictor of Neonatal Acidemia and APGAR Score

Background: Predicting perinatal outcomes based on patterns of fetal heart rate (FHR) remains a challenge. The aim of this study was to evaluate intrapartum FHR variability as predictor for neonatal acidemia and APGAR score.

Methods: This was a retrospective observational study of 552 childbirths. Multivariable linear regression models were used to assess the association between FHR variability and each of the following outcomes: arterial cord blood pH and base deficit, Apgar 1, and 5 scores. Variables used for adjustment were maternal age, comorbidities (gestational diabetes, preeclampsia, maternal fever, and hypertension), parity, gravidity, uterine contractions, and newborn gestational age, and weight at birth.

Results: The following factors were associated with an increased risk of metabolic acidosis and low Apgar scores at birth: increased mean and coefficient of variation (CV) of the FHR, type of delivery and decreased parity. Each 10-beat/min increase in the FHR was associated with an increase of 0.43 mEq/L in the base deficit, and a decrease of 0.01 in the pH, 0.2 in the Apgar 1, and 0.14 in the Apgar 5 scores. Each 10% increase in the CV of the FHR was associated with an increase of 4.05 mEq/L in the base deficit and a decrease of 0.13 in the pH, 1.31 in the Apgar 1, and 0.86 in the Apgar 5 scores.

Conclusion: These data suggest the intrapartum FHR variability is physiologically relevant and can be used for predicting the acidemia and Apgar scores at birth of the newborn infants without severe cases of morbidity and from uncomplicated pregnancies.

When should foetal pH measurements be performed after a prolonged deceleration? An experimental study in a fetal sheep model

OBJECTIVE

The aim of fetal heart rate monitoring during labour is to identify and prevent foetal distress, but its evaluation is not perfect. Fetal scalp blood sampling for pH measurement is one of the second-line methods of monitoring when fetal heart rate is classified as suspicious. This study aims to determine when pH testing should be performed after a prolonged deceleration.

STUDY DESIGN

This was an experimental study in a fetal sheep model. A partial umbilical cord occlusion was performed for seven minutes followed by a recuperation period of 30 min. Hemodynamic parameters (heart rate, mean blood pressure and intra-amniotic pressure) and blood gases were recorded before occlusion (T0), during occlusion (T4), just after the end of occlusion (T7), and then 10, 20 and 30 min after occlusion (T17, T27 and T37 respectively).

RESULTS

Ten experiments were carried out. During partial cord occlusion, the fetal pH decreased significantly to acidosis. After a prolonged deceleration with fetal acidosis, the pH recovered to a normal value, defined by a pH greater than or equal to 7.25, after 20 min of recuperation.

CONCLUSION

After a prolonged deceleration, fetal pH normalizes between 20 and 30 min thereafter. Thus, if a foetal blood sample is indicated, this delay must be respected in order to avoid inducing an unnecessary intervention decision.