Correlation of Suspicious And Pathological Cardiotocography (CTG) with Umbilical Cord Blood Gas Parameters: A Prospective Cohort Study

doi:10.21203/rs.3.rs-5247310/v1

Introduction-Fetal blood sampling is considered the best option in overcoming the increased false positivity of CTG but is not used in many developing countries due to logistics difficulties. Hence, obstetricians highly rely on CTG for diagnosing fetal hypoxia. Studies of suspicious and pathological CTG correlating with umbilical blood parameters are limited. Lactate can be a reliable marker to assess intrapartum hypoxia. However, the correlation of suspicious and pathological CTG with lactate is least studied.

Methodology- A prospective observational cohort study was conducted to correlate suspicious and pathological CTG with umbilical cord arterial blood gas parameters in induced or laboring pregnant women and to compare the maternal and neonatal outcomes.

Results- Out of 2350 women subjected to continuous CTG, 104 and 101 participants had suspicious and pathological CTG, respectively. A statistically significant association of CTG was seen in women with preterm delivery and with the use of tramadol. The association of primary outcomes like pH, base excess, and lactate with CTG findings was significant.

Discussion- Other modalities to confirm acidosis should be used before an intervention in women with suspicious CTG. Drugs like tramadol and agents used for induction may play a role in abnormal CTG tracing in suspicious CTG. Cord blood lactate has a stronger association with CTG when compared with other umbilical cord parameters.

Conclusion- Pathological CTG should be taken cautiously as it carries a greater risk of perinatal distress, but suspicious CTG tracing needs to be supplemented with additional tests before any interventions.

cardiotocography

umbilical cord parameters

suspicious CTG

pathological CTG

Obstetricians rely on cardiotocography (CTG) during labor to make decisions regarding interventions that may lead to an increased rate of cesarean sections. However, CTG has not displayed a consistent correlation with umbilical cord blood gases, which serve as definitive indicators of birth asphyxia. In cases of suspicious CTG, the observed correlation is minimal, underscoring the necessity for a reassessment of fetal monitoring methods during labor to mitigate unnecessary cesarean deliveries.

Fetal heart rate in utero can be monitored with various noninvasive methods like Doppler ultrasound¹, M-mode USG analysis², fetal acoustic stimulation test³, fetal electrography or magnetocardiography⁴, auscultation with the stethoscope, and Electronic Fetal Monitoring (EFM) and with Invasive methods like fetal scalp blood sampling⁵, Fetal pulse oximetry⁶ and near-infra-red spectroscopy⁷.

Electronic Fetal Monitoring (EFM) came into wide use in the 1970s.⁸ Cardiotocography (CTG), a continuous EFM, monitors fetal Heart Rate (FHR) alterations in uterine contractions.⁹ A pH of < 7.15 accurately measures fetal acidemia, which affects the autonomic nervous system, causing fluctuations in fetal heart rates¹⁰. Hence, monitoring of FHR using CTG can be considered to be a surrogate marker to identify fetal hypoxia during labor, to reduce the death of the fetus, and to reduce fetal morbidities like hypoxic-ischemic encephalopathy and cerebral palsy.¹⁰ CTG is now considered to be standard practice in labor management.

A high false positive rate of 99%, low sensitivity of 57%, specificity of 69%, and variability in the interpretation of the CTG by the users was observed with CTG. ^9,10,11. Studies have shown that CTGS has led to increased cesarean sections and operative deliveries with no significant reduction in fetal deaths or morbidities. Fetal blood sampling has been considered the best option for overcoming the increased false positivity of CTG¹⁰. Still, it is not used in many developing countries due to logistics difficulties. An update on NICE guidelines on fetal monitoring in labor found no added advantage of fetal blood sampling for improving fetal and maternal outcomes compared to CTG¹². Hence, obstetricians highly rely on CTG for diagnosing fetal hypoxia.

Even though studies have been done to test for the reliability of CTG findings by correlating with umbilical cord parameters, various limitations were observed due to insufficient sample size, retrospective study designs, and non-standardization of sampling techniques^13,14. Studies of suspicious and pathological CTG correlating with umbilical blood parameters are limited. Studies have shown lactate predicts newborns with low APGAR scores better than cord pH values. So, lactate can be a reliable marker to assess intrapartum hypoxia¹⁵. However, the correlation of suspicious and pathological CTG with lactate is least studied. This study tested the reliability of CTG findings by correlating with umbilical blood parameters and assessed the predictive value of lactate in assessing fetal hypoxia. It also tested the correlation of perinatal outcomes with CTG and the diagnostic accuracy of various umbilical cord blood parameters in diagnosing birth asphyxia.

The study was conducted as a prospective observational cohort in the Department of Obstetrics & Gynaecology at a tertiary care hospital in East India after ethical committee clearance (2021-22/61). The study aimed 1) To correlate suspicious and pathological CTG with umbilical cord arterial blood gas parameters (pH, base excess, and lactate) in induced or laboring pregnant women with gestational age over 34 weeks. 2)to compare the maternal and neonatal outcomes between suspicious and pathological CTG. The study was conducted from July 2021 to June 2023 for a period of 2 years. The study population was pregnant women with singleton pregnancies with a gestational age of more than 34 weeks who delivered in the labor ward of the obstetric unit in the tertiary center. Pregnant women with major congenital anomalies of the fetuses in antenatal USG or detected after delivery, multiple pregnancies, and obstetric emergencies – cord prolapse, ruptured uterus, and abruption placenta were excluded from the study. A total of 2350 consecutive laboring mothers who had completed 34 weeks of gestation undergoing Cardiotocography (CTG) according to the institutional protocol were recruited for the study. The women having suspicious and pathological CTG were identified, and sociodemographic features, obstetric history, and anthropometric measurements like height, weight, BMI, and clinical findings of obstetric examination were recorded. The women who had delivered within 1 hour of having a pathological or suspicious CTG were included in the study.

The study used the Sonicaid CTG machine with an external transducer and a paper speed of 1 cm per minute. Based on the NICE guideline, CTG tracing was categorized as suspicious or pathological, considering its reassuring, non-reassuring, and abnormal features.

After delivery of the baby, the umbilical cord artery was identified, and 2–3 ml of arterial blood was withdrawn in a pre-heparinized, pre-labeled syringe (syringe flushed with 1000U/mL heparin). The blood sample collected was analyzed in an ABG machine (stat Profile pHox Ultra) within 10 minutes of sample collection. The values of cord blood pH < 7.2, base excess of ≥ 8mmol/L, and lactate level > 6mmol/L were taken as abnormal. Details of maternal and fetal outcomes were noted. The data collected was entered into the Microsoft Excel spreadsheet 2019 version and analyzed using statistical software packages (SPSS software version 27). Continuous variables were expressed as a range, mean ± standard deviation, or median after performing a normality test. Categorical variables were expressed in percentage or proportion. A non-parametric test (Wilcoxon-Mann-Whitney U Test) was used for group comparisons. A parametric test (t-test) was used to make group comparisons for birth weight. The Chi-squared or Fisher's exact test was used for categorical data, as appropriate. Point-Biserial/Cramer's V correlation was used to obtain the result. A p-value of less than 0.05 was considered statistically significant.

Out of 2350 women who were subjected to continuous CTG, 205 participants had abnormal CTG. 104 (50.7%) of the participants had suspicious CTG tracings, and 101 (49.3%) of participants had pathological CTG. No significant association was seen in the two groups regarding age and BMI categorization. However, the two groups differed in obstetrics score, gestational age at delivery, and mean BMI. Both suspicious and pathological CTG were seen in primigravidae (76.9% and 62.4% respectively). Mothers who delivered preterm had more interventions due to pathological CTG. (19.8% vs 9.6). [Table I]

Women with no risk factors were found to be more in the suspicious CTG group than in the pathological CTG group, which was found to be statistically significant (56.7% vs 34.7%). FGR was seen more in the pathological group (26.7%) than in the suspicious group (8.7%). Other risk factors did not show a statistically significant correlation. [Table 2]

The majority of participants in the pathological group had drug intake like thyroxine, labetalol, metformin, and insulin, which did not show any significant correlation with CTG. In the suspicious group, a higher association with tramadol was seen, which was substantial (p-0.013). [ Table 3]

A significant association was seen between duration and stages of labor with CTG, where a majority of women in the suspicious group were not in labor (49%), and a significant proportion of women in the pathological group were in first (63.4%) and second stage of labor (6.9%). In the pathological group, the mean labor duration was significantly longer than in the suspicious group. No association of CTG patterns was noted with the onset of labor. No statistical difference existed between spontaneous labor, induction, or augmentation with various agents. [Table 4]

Our study's mean pH was 7.35 for the suspicious group and 7.27 for the pathological group. Abnormal pH (<7.2) was seen in 24.8% of babies born to the pathological CTG, in contrast to only 1% in the suspicious group. The mean lactate level was 2.57 mmol/L vs 5.01 mmol/L, and the mean base excess was -2.9 mmol/L vs -7.56 mmol/L in suspicious vs pathological CTG, respectively. Negative base excess (< -8 mmoL/L) was higher in the pathological group (42.6%) as compared to the suspicious group (3.8%). In the pathological group, there was more percentage of neonates with high umbilical lactate levels (>6 mmol/L) as compared to neonates in the suspicious group (39.6% vs. 4.8%). [ Table 5]

The association of primary outcomes like pH, base excess, and lactate with CTG findings was significant, with a p-value of <0.001. Strength of association between the two variables for pH category, base excess, and lactate level (Cramer's V) = 0.36, 0.46, and 0.42 (Moderate association), respectively. The diagnostic performance of umbilical cord blood parameters in predicting birth asphyxia was assessed. (Figure 2) pH is the best parameter regarding specificity, PPV, and diagnostic accuracy, but sensitivity and negative predictive values were the same for all the umbilical cord parameters assessed. [Table 6].

95.2% and 92.1% of the participants in the suspicious and pathological CTG groups underwent cesarean section, respectively. 4% of the participants in the pathological group and none in the suspicious group were delivered by vacuum [Table 7]. The association of Small for delivery (34.7%), Meconium-stained liquor (59.4%), birth asphyxia (46.5%), mechanical ventilation or CPAP requirement (49.5%), NICU stay (38.6%) and HIE (13.9%) were significantly more in the pathological group. [Table 7].

This study objectively correlated suspicious and pathological CTG to the umbilical blood parameters. Of the women who underwent continuous CTG for the study period, 104 (50.7%) had suspicious CTG tracing, and 101 (49.3%) had pathological tracing. The prospective study by Aboulghar et al. 16 in 2013 and the Prospective Cohort by Kanagal and Praveen in 202117 had an almost equal distribution of suspicious and pathological CTG. 69.8% of women with abnormal CTG were primigravidae. A significant statistical difference was noted between the suspicious and pathological CTG groups, with primigravidae being more prevalent in the suspicious group. The result was similar to a study conducted by Kanagal and Praveen17, where 72% were primigravidae and 28% were multigravidae.

Women with preterm delivery had more pathological CTG tracing, which was statistically significant. Mean BMI was found to be less in the pathological CTG group. The mean BMI of our study was 22.87 ± 2.86 kg/m², while Nazir et al. found a mean BMI of 27 ± 5.28 kg/m2.18 in their study. BMI in our population was mostly in the normal range, and the number of overweight and obese patients was low in the studied population.

Intrauterine growth restriction was a major risk factor that caused a higher number of pathological CTGs. Amongst the drug studies, a higher association with tramadol was seen in the suspicious group, which was significant (p-0.013). Tramadol is a CNS depressant drug that decreases baseline variability. Tramadol is considered an effective analgesic with less maternal and perinatal effects.¹⁹ Further studies are required to assess the effect of Tramadol on CTG changes. It might help in preventing unnecessary cesarean sections. The drugs that are commonly used in pregnancy, like labetalol, nifedipine, metformin, and insulin, did not have an association even though most of the women were on one or more of these drugs.

Most of the women having suspicious CTG were not in labor, while a significant proportion of women with pathological CTG were in the first or second stage of labor. In the suspicious group, more women received dinoprostone gel (18.3%) or misoprostol tablet (2.9%) than the pathological group. Our study was comparable to a study by Megalo et al., where they also found dinoprostone group (16%) and misoprostol (27%) group participants contributed more to suspicious CTG.²⁰ Hence, suspicious CTG was found more in women who were induced with either misoprostol or dinoprostone, indicating the judicial use of the inducing agents.

Our study's mean pH was 7.35 ± 0.04 for the suspicious group and 7.27 ± 0.09 for the pathological group. Abnormal pH (< 7.2) was seen in 24.8% of babies born in women with pathological CTG, in contrast to only 1% in the suspicious group. Unlike our study, Nainani et al. found the mean pH 7.27 ± 0.07 in both groups²¹. Dellinger et al. found even lower mean pH values in the suspicious (7.21 ± 0.08) and pathological groups (7.06 ± 0.14)²². A study by Kanagal et al. showed that subjects with pathological CTG had lower cord pH (< 7.2) in comparison to suspicious CTG (62.6 vs 26.4%)¹⁷. A study by Rahman et al. found pH < 7.2 in 17.4% with suspicious NST and 57.1% with pathological NST²³. A study done by Aboulghar et al. concluded that cord blood pH of less than 7.2 was associated with suspicious CTG in 19.2% of cases and with pathological CTG in 50% of cases¹⁶. They also found 7.24 ± 0.07 as the mean cord blood pH. In a study done by Ray and Ray, 7.253 ± 0.07 was the mean cord blood pH. 18.3% of neonates were having pH < 7.2. They found that 52.5% of participants with abnormal CTG had acidosis²⁴. Abbasalizadeh et al. found that 38.9% of neonates had pH less than 7.2 with non-reassuring CTG. All of them were discharged in good condition²⁵.

Only 3.8% of women in the suspicious CTG category had base excess of < -8mmol/L and only 4.8% had high lactate > 6 mmol/L compared to 42.6% and 39.6% in the pathological CTG group, respectively. These findings emphasize the need to use other modalities to confirm acidosis before an intervention in women with suspicious CTG.

Our study's mean lactate level was 2.57 mmol/L vs 5.01 mmol/L in suspicious vs pathological CTG, respectively. A prospective study by Deshpande et al. found that 17 and 10 samples had high lactate levels (>/= 6mmol/L) out of 69 cases with non-reactive and reactive NST patterns, respectively, which was statistically significant. They concluded that the lactate level predicts fetal acidosis better than the low cord pH value²⁶. In a study by Hameed et al., high lactate levels were associated more with abnormal CTG patterns. The cut-off value was 4.8 mmol/L for cord blood lactate with sensitivity and specificity of 68% and 89% to predict a low Apgar score of 7 after 5 min.²⁷ Gjerris AC, et al suggested a cut off of 8 mmol/l as a better predictor of intrapartum asphyxia.²⁸ In our study, pH, base excess, and lactate were significantly associated with pathological CTG. Also, we found in our study that the strength of the association of CTG tracing with the pH category was 0.36, and the lactate level was 0.42. Hence, lactate level was seen to have a better association with suspicious and pathological CTG. There were no similar studies about suspicious and pathological CTG correlation with lactate. In other studies, Maclachan, T, Sheikh, Pellantova, and Tasnim concluded that pathological CTG has a high predictive value of 38%, 100%, 58%, and 36.2%, respectively, in predicting fetal acidosis in contrast to suspicious CTG.^29–32

Even though the three parameters' sensitivity and negative predictive value were the same, pH had a higher specificity, positive predictive value, and diagnostic accuracy in predicting birth asphyxia compared to base excess and lactate.

In our study, cesarean sections were high in both groups. The increased cesarean delivery rate may be attributed to the fact that no supplementary tests were taken in addition to CTG tracings.

We found birth asphyxia and the requirement of mechanical ventilation or CPAP were significantly more seen in the pathological CTG group. All babies born were alive, irrespective of the CTG category. In our study, MSL was seen in 12.5% with suspicious tracing vs. 46.5% in the pathological group, which was similar to the survey by Nazir et al.; the figure was 14% vs. 51% in suspicious vs. pathological trace.¹⁸

In our study, a higher percentage of NICU requirements was seen in the pathological group than in the suspicious group (38.6% vs. 5.8%), which is similar to a study by Nazir et al. where NICU requirements were 59% and 0% in the pathological and suspicious group respectively.¹⁸ Another study by Kanagal and Praveen also found significantly higher NICU requirements in neonates born to the pathological group (40%) as compared to the suspicious group (22.14%). 55% of babies admitted to NICU had cord pH less than 7.2¹⁷. Deshpande et al. found that the association between cord blood pH and NICU admissions was statistically significant, with a p-value of 0.02. However, a statistically insignificant poor association was found between NST and NICU admission.²⁶ In our study, lactate had more sensitivity and specificity in predicting NICU requirement, whereas pH value was more specific in predicting birth asphyxia. This contradicts a study conducted among non-reassuring FHRs by Ananya et al., where pH had more specificity and sensitivity for NICU admission. But they had kept the lactate cut-off level > 5.5mmol/L.³³

Strength of the study—After a detailed literature review (Google Scholar, PubMed, Medline), we found that ours was the first study to correlate suspicious and pathological CTG with umbilical cord gas parameters. The study was conducted prospectively and consecutively, with no missing data.

Limitations—Supplementary diagnostic modalities for fetal distress, which can enhance the predictive value of suspicious/pathological admission NST, were not done. For each adverse perinatal outcome, multivariate analysis to reduce confounding factors and long-term follow-up of the newborns would have increased the study's strength.

We recommend that other modalities supplement decisions based on suspicious tracing to limit unnecessary interventions. Pathological CTG can be regarded as an alert for obstetricians, at which point more expeditious decisions for delivery need to be made. However, further multi-center, large-scale, randomized controlled trials, especially to understand the effect of drugs like tramadol, and more extended follow-up studies are required for better correlation. Sub-group and multivariate analysis should also be done to depict each parameter's independent contribution and to reduce the effect of confounding factors.

Pathological CTG in the background of high-risk factors should be taken cautiously as it carries a greater risk of perinatal distress and has a high correlation to the umbilical cord parameters, which is the golden standard for assessment of birth asphyxia. However, suspicious CTG tracing needs to be supplemented by additional tests before any interventions. Further studies are required to confirm the findings of the effect of drugs like tramadol and induction agents on CTG findings. As umbilical cord blood parameters are not feasible in many settings in developing countries, with guidelines like NICE giving less importance to fetal blood sampling, we need to rely more on CTG findings and act judiciously.

Acknowledgments --Nil

Funding -- no funding

The authors have no relevant financial or non-financial interests to disclose

Consent for participation in the study was taken from all participants

Ethical approval obtained—mentioned in the manuscript

Author Contribution

Dr Soumyashree Paikaray studied conception and design, protocol, and project development.

Material preparation, Data collection, or management performed by Dr. Saubhagya Kumar Jena

Dr Pankaj Kumar Mohanty did data analysis.

Dr Deepthy Balakrishnan wrote the first draft of the manuscript, and all authors commented on previous versions. All authors read and approved the final manuscript.

Conflict of interest statement

The authors have no relevant financial or non-financial interests to disclose

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Table I

Distribution of baseline characteristics between suspicious and pathological CTG tracing

	CTG Finding
Parameters	Suspicious (n = 104)	Pathological (n = 101)	p-value
Age (Years)	26.02 ± 3.84	27.07 ± 3.98	0.062¹
Obstetric Score***			0.023²
Primigravida	80 (76.9%)	63 (62.4%)
Multigravida	24 (23.1%)	38 (37.6%)
Gestational Age at Delivery***			0.039²
34 weeks to 36 weeks and 6 days	10 (9.6%)	20 (19.8%)
37 weeks to 41weeks and 6 days	94 (90.4%)	81 (80.2%)

BMI (kg/m²) ***	23.28 ± 2.80	22.44 ± 2.88	0.021¹
BMI			0.188¹
<18.5 Kg/m²	1 (1.0%)	3 (3.0%)
18.5-22.9 Kg/m²	54 (51.9%)	63 (62.4%)
23-24.9 Kg/m²	20 (19.2%)	18 (17.8%)
≥25 Kg/m²	29 (27.9%)	17 (16.8%)

***Significant at p<0.05, 1: Wilcoxon-Mann-Whitney U Test, 2: Chi-Squared T

Table 2 Distribution of risk factors

	CTG Finding
Risk Factor:	Suspicious	Pathological	p-value
	(n = 104)	(n = 101)
None***	59 (56.7%)	35 (34.7%)	0.002²
FGR ***	9 (8.7%)	27 (26.7%)	<0.001²
GHTN	15 (14.4%)	17 (16.8%)	0.635²
Oligo/Anhydraminos	14 (13.5%)	17 (16.8%)	0.501²
Borderline Liquor
Hypothyroidism	9 (8.7%)	14 (13.9%)	0.238²
GDM	10 (9.6%)	6 (5.9%)	0.327²
Hemoglobinopathies	7 (6.7%)	5 (5.0%)	0.587²
Overt DM	3 (2.9%)	5 (5.0%)	0.494³
Preeclampsia/Superimposed	2 (1.9%)	6 (5.9%)	0.166³
Preeclampsia
Chronic HTN	0 (0.0%)	1 (1.0%)	0.493³
Doppler Abnormality	0 (0.0%)	1 (1.0%)	0.493³
Chorioamnionitis	0 (0.0%)	0 (0.0%)	1.000²

***Significant at p<0.05, 1: Wilcoxon-Mann-Whitney U Test, 2: Chi-Squared Test, 3: Fisher's Exact Test

FGR-Fetal growth restriction, GHTN-Gestational hypertension, GDM-Gestational diabetes mellitus, Over DM-Overt diabetes mellitus, HTN-Hypertension

Table 3– Drugs and CTG

Drug:	Suspicious (n = 104)	Pathological (n = 101)	p value
Thyroxine	9 (23.1%)	13 (35.1%)	0.247²
Labetalol	18 (46.2%)	24 (64.9%)	0.101²
Nifedipine	7 (17.9%)	6 (16.2%)	0.841²
Metformin	0 (0.0%)	1 (2.7%)	0.487³
Insulin	1 (2.6%)	4 (10.8%)	0.194³
Tramadol***	12 (30.8%)	3 (8.1%)	0.013²
Steroid	0 (0.0%)	0 (0.0%)	1.000²

***Significant at p<0.05, 1: Wilcoxon-Mann-Whitney U Test, 2: Chi-Squared Test, 3: Fisher's Exact Test

Table 4- Onset, mean duration and stage of labor with CTG

Parameters	Suspicious	Pathological P value
Parameters	(n = 104)	(n = 101)
Onset of Labor		0.376³
Spontaneous	42 (40.4%)	56 (55.4%)
Induction with Dinoprostone
	19 (18.3%)	14 (13.9%)
Gel
Induction with Misoprostol	3 (2.9%)	1 (1.0%)
Augmentation with Oxytocin	8 (7.7%)	6 (6.0%)
Mean Duration of Labor
	7.02 ± 2.93	9.16 ± 3.83 0.001¹
(hours)***
Stage of Labor***			0.013²
Not in Labor	51 (49.0%)	30 (29.7%)
First Stage of Labor	50 (48.1%)	64 (63.4%)
Second Stage of Labor	3 (2.9%)	7 (6.9%)

***Significant at p<0.05, 1: Wilcoxon-Mann-Whitney U Test, 2: Chi-Squared Test, 3: Fisher's Exact Test

Table 5- Association of pH, base excess, and lactate with CTG

	CTG
Parameters	Suspicious	Pathological	p-value
	(n = 104)	(n = 101)
pH***	7.35 ± 0.04	7.27 ± 0.09	<0.001¹
Base Excess (mmol/L) ***	-2.90 ± 2.41	-7.56 ± 4.47	<0.001¹
Lactate (mmol/L) * pH Category*	2.57 ± 1.35	5.01 ± 2.71	<0.001¹ <0.001²
<7.2 (abnormal)	1 (1.0%)	25 (24.8%)
≥7.2 HCO3***	103 (99.0%)	76 (75.2%)	<0.001²
<17 mmol/L	2 (1.9%)	35 (34.7%)
>17 mmol/L Base Excess***	102 (98.1%)	66 (65.3%)	<0.001²
Normal	100 (96.2%)	58 (57.4%)
Abnormal (< -8mmol/L) Lactate***	4 (3.8%)	43 (42.6%)	<0.001²
≤6 mmol/L	99 (95.2%)	61 (60.4%)
>6 mmol/L(high)	5 (4.8%)	40 (39.6%)

***Significant at p<0.05, 1: Wilcoxon-Mann-Whitney U Test, 2: Chi-Squared Test

Table 6 - Comparison of the diagnostic performance of various umbilical cord parameters in predicting birth asphyxia

Predictor	AUROC	95% CI	P	Sn	Sp	PPV	NPV	DA
pH	0.984	0.967-1	<0.001	94%	99%	96%	98%	98%
Base Excess (mmol/L)	0.971	0.942-0.999	<0.001	94%	97%	93%	98%	97%
Lactate (mmol/L)	0.973	0.939-1	<0.001	94%	97%	91%	98%	96%

AUROC: Area under ROC curve; CI: Confidence interval; P: P value; PPV: Positive predictive value; NPV: Negative predictive value; DA: Diagnostic Accuracy.

Table 7 - Association of secondary outcomes with CTG

	CTG Finding
Parameters	Suspicious (n = 104)	Pathological (n = 101)	p value
Size for Date***			<0.001³
AFD	91 (87.5%)	65 (64.4%)
SFD	12 (11.5%)	35 (34.7%)
LFD	1 (1.0%)	1 (1.0%)

    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p><strong>MSL&nbsp;***</strong></p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>13&nbsp;(12.5%)</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>60&nbsp;(59.4%)</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&lt;0.001<sup>2</sup></p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p><strong>Birth&nbsp;Asphyxia***</strong></p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>7&nbsp;(6.7%)</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>47&nbsp;(46.5%)</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&lt;0.001<sup>2</sup></p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p>&nbsp;</p>
            <p><strong>Mechanical</strong></p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>&nbsp;</p>
            <p>&nbsp;</p>
            <p>6&nbsp;(5.8%)</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>&nbsp;</p>
            <p>&nbsp;</p>
            <p>50&nbsp;(49.5%)</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&nbsp;</p>
            <p>&lt;0.001<sup>2</sup></p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p><strong>Ventilation/CPAP***</strong></p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>&nbsp;</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>&nbsp;</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&nbsp;</p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p><strong>NICU&nbsp;Requirement&nbsp;***</strong></p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>6&nbsp;(5.8%)</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>39&nbsp;(38.6%)</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&lt;0.001<sup>2</sup></p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p><strong>HIE***</strong></p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>&nbsp;</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>&nbsp;</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&lt;0.001<sup>2</sup></p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p>None</p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>103&nbsp;(99.0%)</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>87&nbsp;(86.1%)</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&nbsp;</p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p>Grade&nbsp;1</p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>1&nbsp;(1.0%)</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>14&nbsp;(13.9%)</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&nbsp;</p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p>Grade&nbsp;2</p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>0&nbsp;(0.0%)</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>0&nbsp;(0.0%)</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&nbsp;</p>
        </td>
    </tr>
    <tr>
        <td valign="top" style="width: 28.8779%;">
            <p>Grade&nbsp;3</p>
        </td>
        <td valign="top" style="width: 27.8878%;">
            <p>0&nbsp;(0.0%)</p>
        </td>
        <td valign="top" style="width: 32.8383%;">
            <p>0&nbsp;(0.0%)</p>
        </td>
        <td valign="top" style="width: 10.396%;">
            <p>&nbsp;</p>
        </td>
    </tr>
</tbody>

***Significant at p<0.05, 1: Wilcoxon-Mann-Whitney U Test, 2: Chi-Squared Test, 3: Fisher's Exact Test,

Correlation of Suspicious And Pathological Cardiotocography (CTG) with Umbilical Cord Blood Gas Parameters: A Prospective Cohort Study

Status:

Version 1

Abstract

Figures

Significance

Introduction

MATERIAL AND METHODS

Results

Discussion

Conclusion

Declarations

References

Tables

Distribution of baseline characteristics between suspicious and pathological CTG tracing

Status:

Version 1