European Journal of Cardiovascular Medicine

Pregnancy is considered a physiological process, yet a considerable proportion become “high-risk” due to maternal, fetal, or placental complications. High-risk pregnancies account for a large share of perinatal morbidity and mortality, particularly in developing regions such as Northeast India, where healthcare disparities, delayed antenatal care, and limited resources amplify adverse outcomes. Early identification of fetal distress in these cases is critical for improving neonatal survival.^[1,2]

Cardiotocography (CTG) remains one of the most widely used methods for fetal surveillance. Introduced in the 1960s, CTG continuously records fetal heart rate (FHR) and uterine contractions, allowing clinicians to interpret fetal oxygenation and autonomic responses. A normal CTG pattern indicates good fetal health, whereas non-reassuring or pathological patterns may reflect hypoxia or acidosis.^[3,4] Despite its widespread use, CTG has been debated for its accuracy due to observer variation and false-positive results.^[5,6]

Clinical Significance of CTG Findings

CTG helps guide obstetric decisions:

• Normal: Continue routine monitoring.
• Suspicious: Close observation and further tests if needed.
• Pathological: Immediate action like repositioning, oxygen, or urgent delivery.

CTG Monitoring in Various Clinical Settings

• Cardiotocography (CTG) is utilized in two main situations — before the onset of labor (antenatal) and during labor (intrapartum) — to evaluate fetal wellbeing.
• Antenatal CTG monitoring

Antenatal CTG is conducted to monitor the fetal condition in pregnancies considered high-risk. It is commonly indicated in cases of decreased fetal movement, maternal disorders like hypertension and diabetes, intrauterine growth restriction (IUGR), and post-term gestation. By identifying abnormal fetal heart rate (FHR) patterns, antenatal CTG enables early clinical interventions to prevent potential fetal distress.

• Intrapartum CTG Monitoring

Intrapartum CTG involves continuous observation of fetal heart rate alongside uterine contractions during labor. It helps detect signs of fetal compromise, such as tachycardia, bradycardia, or variable decelerations. This real-time assessment supports timely clinical decisions, including the need for caesarean section or assisted vaginal delivery.

Limitations
CTG may give false positives and vary between observers. Standardized training improves accuracy.

Several studies have demonstrated CTG’s usefulness in detecting early fetal distress. However, its predictive value varies, and unnecessary cesarean deliveries due to overinterpretation of non-reassuring CTG remain a concern. ^[7,8] Hence, there is a need to evaluate its diagnostic performance and its true association with perinatal outcomes in specific populations. ^[9,10]

AIMS AND OBJECTIVES

Aim
To study the association of abnormal cardiotocography (CTG) patterns with perinatal outcomes in high-risk pregnancies.

Objectives

1. To determine the incidence of abnormal CTG patterns in high-risk pregnancies.
2. To assess the association of abnormal CTG with adverse perinatal outcomes such as low Apgar scores, NICU admissions, and perinatal mortality.
3. To evaluate the diagnostic accuracy of CTG by calculating sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

To compare CTG findings among different high-risk conditions such as pre-eclampsia, IUGR, and GDM

Study Design

A prospective cross-sectional study was conducted in the Department of Obstetrics and Gynaecology, Tezpur Medical College and Hospital, Assam over a period of 12-month, from September 2023 to August 2024., after obtaining ethical approval from the Institutional Ethics Committee. All participants provided informed consent.

Study Population

A total of 180 pregnant women were enrolled based on predefined inclusion and exclusion criteria. All were ≥37 weeks of gestation and had at least one high-risk factor.

Inclusion Criteria

• Singleton pregnancies with cephalic presentation.
• Gestational age ≥37 weeks.
• Presence of one or more high-risk factors (PIH, GDM, IUGR, anemia, oligohydramnios, etc.).

Exclusion Criteria

• Known congenital fetal malformations.
• Multiple pregnancies.
• Preterm labour (<37 weeks).
• Patients refusing participation.

High-Risk Factors Included

• Pregnancy-induced hypertension (PIH) and pre-eclampsia.
• Gestational diabetes mellitus (GDM).
• Intrauterine growth restriction (IUGR).
• Oligohydramnios and polyhydramnios.
• Maternal anemia.
• Previous cesarean section.
• Post-term pregnancy.
• Rh incompatibility.

Methods of Data Collection

• Patient Selection and Enrolment
• Patient details, including demographic data, obstetric and medical history, and risk factors, were recorded using a structured proforma. General and obstetric examinations assessed fundal height, presentation, FHR, and uterine contractions.

• CTG Monitoring

A 20-minute admission CTG was performed and categorized as normal, suspicious, or abnormal. Abnormal traces were repeated, and women with persistent abnormalities were continuously monitored with interventions as per standard protocols.

• Intrapartum Monitoring and Management

FHR and uterine contractions were monitored intermittently. Amniotic fluid was checked for meconium, and the mode of delivery (vaginal, instrumental, or caesarean) was documented.

• Neonatal Outcomes

Neonatal assessment included APGAR scores at 1 and 5 minutes, NICU admissions, and any cases of stillbirth or neonatal death.

• DataAnalysis

Data were entered in Microsoft Excel and analyzed using SPSS v20.0. The chi-square test assessed the association between CTG findings and perinatal outcomes, with p<0.05 considered significant.

• Ethical Considerations

Ethical approval was obtained from the Institutional Ethical Committee, and written informed consent was taken from all participants.

• Methodology

Each participant underwent a 20-minute admission CTG using a standardized fetal monitor upon hospital admission. Tracings were classified according to NICE (2014) guidelines:

• Normal (Reactive): Baseline 110–160 bpm, variability 5–25 bpm, ≥2 accelerations, no decelerations.
• Suspicious (Non-reactive): One non-reassuring feature, absence of accelerations, or reduced variability.
• Pathological (Abnormal): Two or more non-reassuring features or one abnormal feature such as prolonged deceleration, late deceleration, or bradycardia.

Maternal management was based on obstetric assessment and CTG interpretation. The labour process was observed for mode of delivery, and neonatal outcomes were recorded including Apgar score at 1 and 5 minutes, NICU admission, and perinatal mortality (death within 7 days of birth).

Outcome Variables

1. Primary outcomes: Mode of delivery, Apgar score, and perinatal mortality.
2. Secondary outcomes: NICU admissions and need for neonatal resuscitation.

Statistical Analysis

Data were entered in Microsoft Excel and analyzed using SPSS version 20.0. Descriptive statistics summarized patient demographics and outcomes. Associations between CTG patterns and perinatal outcomes were analyzed using the Chi-square test. Sensitivity, specificity, PPV, and NPV of CTG were calculated. A p-value <0.05 was considered statistically significant

Demographic Profile

Among 180 patients, the majority (60%) were between 21–30 years. Primigravidas constituted 57%, and multigravidas 43%. The predominant high-risk factors were PIH (30%), IUGR (20%), and GDM (15%).

CTG Distribution

• Reactive: 127 (70.55%)
• Non-reactive: 35 (19.44%)
• Pathological: 18 (10%)

A significant correlation was observed between CTG pattern and mode of delivery (p < 0.0001). Pathological CTG was associated with increased cesarean delivery rates.

Chi-Square Test Results

• χ² = 52.16, p < 0.0001, df = 4
• Statistically significant association between CTG findings and mode of delivery.

The highest percentage of reactive CTG is observed in spontaneous vaginal deliveries (90.5%), Indicating good fetal well-being in these cases. The highest percentage of pathological CTG is found in instrumental deliveries (27.8%), reflecting a higher likelihood of fetal distress requiring operative intervention

Chi-Square Test: χ² = 21.33, p = 0.0934 (Not Significant)

No statistically significant association was found between risk factors and CTG findings.

The distribution of CTG findings across different risk factors highlights certain trends, though the overall association is not statistically significant. Among the risk factors, IUGR cases had the highest percentage of pathological CTG findings (25%), indicating a greater likelihood of fetal distress and compromised oxygenation. This aligns with existing clinical knowledge that growth-restricted fetuses are at higher risk of hypoxia and adverse perinatal outcomes. On the other hand, the highest percentage of reactive CTG was found in PROM cases (81.48%).

Statistical association
CTG findings were significantly associated with Apgar score and NICU admission (p < 0.05).

Our findings align with previous studies such as Nagpal et al.^[11], Naeem et al.^[12], and Markam et al.^[13] who reported that pathological CTG significantly correlated with low Apgar scores and increased NICU admissions. Similarly, Sharma et al.^[14] observed a high negative predictive value for reactive CTG, supporting its reliability in identifying fetal well-being in low-resource settings.

Alfirevic et al.^[15] in a Cochrane review concluded that continuous CTG reduced neonatal seizures but increased cesarean delivery rates. Kumar et al.^[16] and Powell et al.^[17] also supported combining CTG with Doppler velocimetry to enhance predictive accuracy. Rodriguez et al.^[18] explored AI-based CTG interpretation systems to minimize observer variability, a growing area of innovation in perinatal medicine.

Our study confirms that abnormal CTG patterns are significantly associated with adverse perinatal outcomes, particularly in high-risk conditions such as PIH, IUGR, and GDM. While CTG demonstrates high sensitivity, its moderate positive predictive value suggests that it should not be used in isolation.^[19,20]

Clinical Implications

The high cesarean rate (approximately 32%) observed in this study underscores CTG’s influence on obstetric decision-making. However, as highlighted by Parer and King (2020), many non-reassuring CTG patterns do not equate to fetal hypoxia, emphasizing the need for cautious interpretation. Overreliance may lead to unnecessary surgical interventions and associated complications.

CTG in Specific High-Risk Conditions

• PIH: Most cases exhibited non-reassuring CTG patterns, reflecting placental insufficiency. Late decelerations were common.
• IUGR: Showed the highest proportion of pathological CTG, consistent with chronic fetal hypoxia.
• GDM: Reactive CTG predominated, likely due to good metabolic control among patients.

These correlations align with findings by Powell et al. (2021), who demonstrated a similar distribution of CTG abnormalities across these conditions.

Comparative Literature Review

Numerous studies worldwide have evaluated CTG’s role. Alfirevic et al. (2020) concluded that continuous CTG reduced neonatal seizures but increased cesarean deliveries. Kumar et al. (2022) found that combining CTG with Doppler velocimetry increased predictive accuracy from 70% to 90%. Emerging technologies such as AI-based CTG interpretation systems (Rodriguez et al., 2023) are being explored to minimize observer variability.

Strengths of the Study

• Prospective design ensuring real-time data collection.
• Use of standardized NICE guidelines for CTG interpretation.
• Inclusion of diverse high-risk categories reflecting the regional population.

LIMITATIONS

• Small sample size from a single tertiary center limits external validity.
• Absence of biochemical validation (fetal scalp pH or lactate measurement).
• Subjectivity in CTG interpretation despite standardized criteria.

FUTURE SCOPE

Future studies should incorporate multimodal fetal assessment—combining CTG with Doppler and biochemical parameters—to enhance diagnostic precision. Moreover, training programs and inter-observer reliability assessments should be introduced to standardize CTG interpretation in Indian obstetric units.

SUMMERY

This hospital-based observational study evaluated the association between cardiotocography (CTG) findings and perinatal outcomes among 180 high-risk pregnancies admitted to the Department of Obstetrics and Gynaecology, Tezpur Medical College. Most participants were aged between 26 and 29 years. A significant correlation was observed between CTG patterns and mode of delivery (p < 0.0001). Women with reactive CTG mostly had spontaneous vaginal deliveries and healthy neonates, while pathological or non-reactive CTG was linked with higher rates of cesarean sections, fetal distress, and NICU admissions. Although the relationship between specific risk factors and CTG findings was not statistically significant, conditions such as IUGR, PIH, and diabetes showed more adverse neonatal outcomes. Babies born to mothers with PIH had the highest neonatal mortality, whereas diabetes contributed to macrosomia and increased NICU admissions. Apgar scores were strongly associated with CTG results; reactive CTG indicated better neonatal health. The most frequent indication for cesarean section was fetal distress. CTG demonstrated good sensitivity (80%) and specificity (80.74%) but a low positive predictive value (13.33%), suggesting some false positives. In conclusion, CTG is a useful non-invasive tool for early detection of fetal distress, though complementary assessments are recommended for accurate decision-making

Abnormal CTG patterns are significantly associated with adverse perinatal outcomes in high-risk pregnancies. Pathological CTG strongly predicts cesarean delivery, low Apgar scores, and NICU admissions. While CTG demonstrates high sensitivity and negative predictive value, its moderate PPV suggests that it should not be used in isolation for decision-making.

Integration with additional diagnostic tools, alongside sound clinical judgment, remains essential to optimize maternal and fetal outcomes. Despite its limitations, CTG remains a cornerstone of fetal surveillance, especially in resource-constrained settings where timely identification of fetal distress can be lifesaving

1. Behuria S, Nayak R. Admission cardiotocography as a screening test in high‑risk pregnancies and its co‑relation with perinatal outcome. Int J Reprod Contracept Obstet Gynecol. 2016;5(10):3525‑28.
2. Nandmer G, Jaiswal S, Namdeo P. Comparative efficacy of admission cardiotocography in high risk and low risk pregnancies in predicting neonatal outcome. Int J Reprod Contracept Obstet Gynecol. 2021;8(1):10770.
3. Kumar A, Jaju PB. Admission test cardiotocography in labour as a predictor of fetal outcome in high‑risk pregnancies. Int J Reprod Contracept Obstet Gynecol. 2019;8(4):1331‑36.
4. Thakur A, Singh KN, Sahani S. Study of admission cardiotocography screening of high‑risk obstetric cases and its correlation with perinatal outcome. Indian J Obstet Gynecol Res. 2018;5(4):6575.
5. Gupta M, Gupta P. Role of cardiotocography in high risk pregnancy and its correlation with increased caesarean section rate. Int J Reprod Contracept Obstet Gynecol. 2016;6(5).
6. Kanwat B, Singhal M, Chauhan M, Chaubisa P. Cardiotocography for predicting fetal prognosis in high‑risk pregnancy. Int J Reprod Contracept Obstet Gynecol. 2023;12(4):874‑82.
7. Nagpal A, Tyagi M, Gupta S, Gupta M. Predictive value of admission and intrapartum cardiotocography in normal and high‑risk antenatal women. Int J Reprod Contracept Obstet Gynecol. 2023;12(3).
8. Khatun M, Siddika A, Akthar S, Chowdhury SM, Nargish U, Ali Y, et al. Antepartum CTG in high risk pregnancy and fetal outcome at SZMCH, Bogura. Int J Clin Obstet Gynaecol. 2024;8(3):43‑47.
9. Akther H, Jahan C, Beg MO, Elora N. Antepartum CTG in high‑risk pregnancy and fetal outcome in a tertiary hospital. North East Med J. 2016.
10. Kanupriya S, Pathan M, Shah M. Intrapartum fetal monitoring by cardiotocography and its correlation with labour outcome. Int J Reprod Contracept Obstet Gynecol. 2020;9(2).
11. Alfirevic Z, Gyte GML, Cuthbert A, Devane D. Continuous cardiotocography for fetal assessment during labour. Cochrane Database Syst Rev. 2017;2:CD006066.
12. Al‑Yousif M, et al. Automated pre‑processing and classification of CTG: a systematic review. J Med Eng Technol. 2021.
13. Nabipour Hosseini ST, Abbasalizadeh F, et al. CTG monitoring before labor in infants with and without asphyxia. BMC Pregnancy Childbirth. 2023;23:758.
14. Priya K, Dharmavijaya MN. Role of CTG in predicting fetal outcomes in both high‑risk and low‑risk pregnancies. Int J Clin Obstet Gynaecol. 2024;8(4):98‑104.
15. Hosny M, et al. Impact of pathological CTG in high‑risk pregnancies. Life & Science. 2024;5(3).
16. Powell T, et al. Comparison of visual and computerized antenatal CTG in prevention of perinatal morbidity. PubMed. 2021.
17. Ponimanskaya V, et al. A physiological approach to interpretation of CTG. Obstet Gynecol. 2021;73(1):19‑33.
18. Rodriguez M, et al. Conventional vs computerized CTG analysis and perinatal outcomes: a systematic review. 2023.
19. Thomas J, et al. Professionals’ views of fetal monitoring during labour: a systematic review. BMC Pregnancy Childbirth. 2012;12:166.
20. Allu SL, Dwarakanath L, Indumathi M, Indira H. Role of admission CTG in predicting fetomaternal outcome: a prospective observational study. Int J Gynaecol Obstet Sci. 2025;7(2):01‑06