Motherhood is a dream of every woman, and the ultimate goal of having a healthy mother and a healthy baby is the responsibility of every obstetrician [1]. Fetal surveillance during labour is a crucial component for ensuring the delivery of a healthy baby with minimal intervention [2]. Furthermore, labour poses physiological stress to the fetus. During uterine contraction, there is a 60% reduction in uteroplacental perfusion, resulting in transient fetal and placental hypoxia. Most healthy fetuses tolerate this amount of hypoxia by peripheral chemoreflex activation, which in turn causes the redistribution of oxygenated blood to critical organs, including the heart, brain and adrenals [3], but not all fetuses are fortunate enough to tolerate this stress. Hence, continuous intrapartum electronic fetal heart rate monitoring is very essential to identify such fetuses at risk of developing fetal hypoxia and its related complications [4]. Cardiotocography (CTG) is one such way of assessing fetal well-being, as it records fetal heart rate (FHR), fetal movements and uterine contraction patterns to know the cause of hypoxia [5]. Admission CTG can be used for triaging fetuses at risk of hypoxia by recording FHR and uterine activity over 20 minutes during admission of term antenatal women in the labour ward [6], as early diagnosis can help in preventing many long-lasting fetal complications due to hypoxia through timely intervention. Hence, the present study was conducted with the aim to evaluate the role of admission CTG in predicting fetal hypoxia in term antenatal women and to correlate the results with the overall perinatal and maternal outcomes.
Pregnant women with gestation < 37 weeks;
multifetal gestation;
lie or presentation other than cephalic;
dead or congenitally malformed fetus;
history of previous cesarean section;
with abruption;
cord prolapse;
or uterine rupture;
those reporting in the second stage of labour; use of sedative in mothers 24 hours before testing and those refusing to participate were excluded from the study.
Normal/Reactive/Reassuring: Baseline FHR 110–160 beats per min (bpm), or baseline variability > 5bpm or absence of any decelerations or at least two accelerations (>15 bpm for >15 sec) in 20 minutes duration.
Suspicious/equivocal: Moderate tachycardia (161–180 bpm)/ bradycardia (100–109 bpm) or reduced baseline variability (< 5bpm) for > 40 mins but < 90 mins, although baseline heart rate remains normal (110–160 bpm) or presence of deceleration (early/variable/late).
Ominous/Pathological: Baseline FHR >180 bpm or < 100 bpm or Sinusoidal pattern >10 mins (regular oscillation of baseline FHR with the absence of long-term variability) or baseline variability (< 5 bpm) for > 90mins.
Women with reactive tracing were monitored by either intermittent auscultation every 30 minutes in the first stage and every 5 minutes in the second stage of labour or with continuous cardiotocograph. The women with suspicious tracing were monitored with continuous cardiotocograph, and any abnormal FHR tracing with significant decelerations (variable or prolonged deceleration), baseline FHR < 110bpm or > 160bpm with loss of variability, were considered as having fetal distress and were delivered by either instrumental delivery or by emergency cesarean section. The colour of the liquor, mode of delivery, neonatal Apgar scores at one and five minutes, neonatal birth weight, need for neonatal resuscitation and neonatal intensive care unit (NICU) admission were recorded in the datasheet. Results of the admission CTG test were then compared with various labour outcome variables, including the incidence of fetal distress, overall neonatal, maternal outcomes, and the efficacy of the admission test in predicting perinatal outcomes in both low- and high-risk pregnancies.
Statistical analysis of data was performed using Statistical Package for Social Sciences (SPSS) software version 21.0. Categorical variables were presented as numbers and percentages (%) and continuous variables as mean ± SD and median. Qualitative variables were correlated using the Chi-Square test. The diagnostic test was used to calculate sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV). A p-value of < 0.05 was considered statistically significant.
The present research involving human subjects was conducted following the ethical standards of all applicable national and institutional committees and the World Medical Association’s Helsinki Declaration. It was conducted after informed written consent from the participants and ethical approval from the Institutional Ethical Committee (IEC number: 2015/571).
Sociodemographic features
Parameters | Number (n) | Percentage (%) |
---|---|---|
≥ 20–< 30 | 94 | 94.0% |
≥ 30 | 6 | 6.0% |
Booked | 55 | 55.0% |
Unbooked | 45 | 45.0% |
≥ 37–< 40 | 98 | 98.0% |
≥ 40 | 2 | 2.0% |
Multigravida | 57 | 57.0% |
Primigravida | 43 | 43.0% |
Low-risk group | 51 | 51.0% |
High-risk group | 49 | 49.0% |
Relationship between the colour of liquor and CTG results in both low- and high-risk pregnancies.
Admission CTG |
|||||
---|---|---|---|---|---|
Meconium Staining | Reactive | Suspicious | Ominous | Total | p-value |
Clear | 47 (95.9%) | 1 (2.04%) | 1 (2.04%) | 49 | <0.001 |
Meconium-stained | 0 (0%) | 1 (50.0%) | 1 (50.0%) | 2 | |
Total | 47 (92.2%) | 2 (3.9%) | 2 (3.9%) | 51 | |
Clear | 20 (43.5%) | 16 (34.8%) | 10 (21.7%) | 46 | 0.018 |
Meconium-stained | 0 (0%) | 0 (0%) | 3 (100.0%) | 3 | |
Total | 20 (40.8%) | 16 (32.7%) | 13 (26.5%) | 49 |
Relationship between the admission CTG results and the mode of delivery in the low-and high-risk groups
Groups |
|||||
---|---|---|---|---|---|
Admission CTG | Mode of Delivery | Low Risk | High Risk | Total | p-value |
ND | 41 (87.2%) | 15 (75.0%) | 56 (83.6%) | ||
LSCS | 2 (4.3%) | 1 (5.0%) | 3 (4.5%) | ||
Instrumental | 4 (8.5%) | 4 (20.0%) | 8 (11.9%) | ||
Total | 47 (100.0%) | 20 (100.0%) | 67 (100.0%) | ||
ND | 0(0%) | 4 (25.0%) | 4 (22.2%) | ||
LSCS | 1 (50.0%) | 4 (25.0%) | 5 (27.8%) | ||
Instrumental | 1 (50.0%) | 8 (50.0%) | 9 (50.0%) | ||
Total | 2 (100.0%) | 16 (100.0%) | 18 (100.0%) | 0.0001 | |
ND | 0(0%) | 0 (0%) | 0 (0%) | ||
LSCS | 2 (100.0%) | 13 (100.0%) | 15 (100.0%) | ||
Instrumental | 0(0%) | 0 (0%) | 0 (0%) | ||
Total | 2 (100.0%) | 13 (100.0%) | 15 (100.0%) | ||
ND | 41 (80.4%) | 19 (38.8%) | 60 (60.0%) | ||
LSCS | 5 (9.8%) | 18 (36.7%) | 23 (23.0%) | ||
Instrumental | 5 (9.8%) | 12 (24.5%) | 17 (17.0%) | ||
Total | 51(100.0%) | 49 (100.0%) | 100 (100.0%) |
Relationship between admission CTG and perinatal outcome
Groups | Parameters | Admission CTG |
p-value | ||
---|---|---|---|---|---|
Reactive | Suspicious | Ominous | |||
≥ 7 | 46 (97.9%) | 1 (50.0%) | 1 (50.0%) | 0.0005 | |
< 7 | 1 (2.1%) | 1 (50.0%) | 1 (50.0%) | ||
≥ 7 | 47 (100.0%) | 2 (100.0%) | 2 (100.0%) | No correlation observed | |
< 7 | 0 (0%) | 0 (0%) | 0 (0%) | ||
Yes | 0 (0%) | 0 (0%) | 0 (0%) | No correlation observed | |
No | 47 (100.0%) | 2 (100.0%) | 2 (100.0%) | ||
Yes | 3 (6.4%) | 1 (50.0%) | 1 (50.0%) | 0.019 | |
No | 44 (93.6%) | 1 (50.0%) | 1 (50.0%) | ||
≥ 7 | 17 (85.0%) | 12 (75.0%) | 5 (38.5%) | 0.015 | |
< 7 | 3 (15.0%) | 4 (25.0%) | 8 (61.5%) | ||
≥ 7 | 20 (100.0%) | 16 (100.0%) | 13 (100.0%) | No correlation observed | |
< 7 | 0 (0%) | 0 (0%) | 0 (0%) | ||
Yes | 0 (0%) | 1 (6.3%) | 5 (38.5%) | 0.03 | |
No | 20 (100.0%) | 15 (93.7%) | 8 (61.5%) | ||
Yes | 3 (15.0%) | 5 (31.3%) | 10 (76.9%) | 0.001 | |
No | 17 (85.0%) | 11 (68.7%) | 3 (23.1%) |
Comparison of sensitivity, specificity, negative and positive predictive value of admission CTG in the prediction of neonatal outcomes between low- and high-risk pregnancies.
Group | Parameter | Sensitivity (95% CI) | Specificity (95% CI) | Positive Predictive Value (95% CI) | Negative Predictive Value (95% CI) |
---|---|---|---|---|---|
Apgar score at 1-min | 50.0% (1.26–98.7%) | 97.9% (88.7–99.9%) | 50.0% (1.3–98.7%) | 97.9% (88.7–99.9%) | |
NICU Admission | 25.0% (0.6–80.6%) | 97.8% (88.2–99.9%) | 50.0% (1.3–98.7%) | 93.6% (82.5–98.7%) | |
Apgar score at 1-min | 72.7% (39.0–93.9%) | 77.3% (54.6–92.2%) | 61.5% (31.6–86.1%) | 85.0% (62.1–96.8%) | |
NICU Admission | 76.9% (46.2–94.9%) | 85.0% (62.1–96.8%) | 76.9% (46.2–94.9%) | 85.0% (62.1–96.8%) |
Admission CTG or the admission test is the most commonly used test for surveillance of fetal well-being, especially in high-risk pregnancies all over the world [8]. In the present prospective study, the FHR tracings on the admission test in low- and high-risk term antenatal women were observed in the relation to the overall perinatal and maternal outcomes. In our study, of the total 100 participants, 51 belonged to the low-risk group and 49 to the high-risk group with anemia (20.41%), hypertensive disorders of pregnancy (20.41%) and seizure disorders (20.41%) being the most common risk factors. A similar study conducted to assess the role of admission CTG as a predictor of the neonatal outcome included 67% multigravida and 34% primigravida women, and in their study also anemia (22%) was the most prevalent risk factor observed [5]. In the present study, the admission CTG was reactive in 67% (47 in low-risk and 20 in the high-risk group), suspicious in 18% (2 in low-risk and 16 in high-risk) and ominous in 15% (2 in low-risk and 13 in high-risk). In the low-risk group, 50% of participants with suspicious and ominous tracing on admission CTG had meconium-stained fluid, whereas in the high-risk group 100% of participants with ominous tracing had meconium-stained fluid. This was similar to the results of a study conducted on 160 term antenatal women, which reported that the admission CTG was found to be reactive in 77%, equivocal in 14.4% and ominous in 8.7% of women. They also reported that meconium-stained fluid was more common in women with ominous tracing (72%) [2]. Similar results were reported by other studies also, which found a significant correlation between non-reactive (suspicious/ ominous) admission CTG results and meconium-stained fluid [5, 9, 10, 11]. Another recent study conducted on 130 term high-risk antenatal women reported that the results of admission test were reactive in 73.1%, equivocal in 14.6% and ominous in 12.3%, and similar to our study they also observed a significant correlation between the results of admission CTG and mode of delivery with increased cesarean section rate in women with equivocal or ominous tracing [12]. Similar results of increased risk of operative delivery in mothers having pathological CTG were reported by a recent study [9].
In our study, a significant correlation was found between neonatal Apgar scores, need for resuscitation and NICU admission in neonates delivered to mothers with ominous or suspicious admission CTG results. Similar to our results, another study reported a significant correlation between abnormal (suspicious/ominous) admission test findings and poor Apgar scores at birth, need for neonatal resuscitation and increased risk of NICU admission (p = 0.000) [12]. A similar recent study found no significant correlation between admission CTG findings and the fifth-minute Apgar scores [13]. Other studies have also reported a significantly increased incidence of fetal distress, meconium-stained fluid, Apgar score < 7 and NICU admission in neonates delivered to mothers with pathological patterns on admission CTG tracing [11, 14, 15, 16].
In the present study, the admission CTG had high specificity and NPV in both low- and high-risk groups in the prediction of Apgar scores at birth (97.9% and 97.9% in the low-risk group vs. 77.3% and 85.0% in high-risk group) and NICU admission (97.8% and 93.6% in the low-risk group vs. 85.0% and 85.0% in high-risk group). A similar study reported a sensitivity of 44% specificity of 95% and a PPV of 50% for admission CTG in the prediction of 5-min Apgar scores [17]. Another systematic review reported that the admission CTG test had a specificity between 78% and 98%, and NPV between 67% and 99%, hence, indicating the role of admission CTG in the identification of women with no adverse outcomes [6].
Admission CTG is a simple, easy, cost-effective, non-invasive screening method useful in the detection of fetal distress already present at the time of admission and can play a crucial role in predicting fetal well-being during labour. It also helps in planning early intervention so as to prevent adverse perinatal outcomes, especially in hospitals with limited resources and huge patient loads. The major drawback associated with admission CTG is that it increases the incidence of cesarean sections in places where fetal blood sampling is not performed to confirm fetal hypoxia during labour.
The present study was conducted for a short duration and with limited sample size. The number of high-risk cases included in the study was only 49. In the future, we can plan to conduct a multicentric study with a large sample size of only high-risk pregnant women. Furthermore, we will include fetal blood sampling to confirm fetal hypoxia before planning for emergency operative delivery, so as to reduce the risk of unnecessary cesarean sections.
The admission CTG was reactive in 67% (47 women in low-risk and 20 in the high-risk group), suspicious in 18% (2 in low-risk and 16 in high-risk) and ominous in 15% (2 in low-risk and 13 in high-risk) of participants.
In the low-risk group, 50% of participants with suspicious and ominous tracing on admission CTG had meconiumstained fluid, whereas in the high-risk group 100% with ominous tracing had meconium-stained fluid.
A significant correlation was observed between the results of admission CTG and mode of delivery with increased cesarean section rate in women with equivocal or ominous tracing.
A statistically significant correlation was observed between abnormal CTG results and adverse neonatal outcomes, including poor Apgar scores, need for neonatal resuscitation and NICU admission in both low- and high-risk groups.
No significant correlation was observed between the admission test results and neonatal birth weight.
The admission CTG had high specificity and NPV in both low- and high-risk groups in the prediction of Apgar scores at birth (97.9% and 97.9% in the low-risk group vs. 77.3% and 85.0% in the high-risk group) and NICU admission (97.8% and 93.6% in the low-risk group vs. 85.0% and 85.0% in high-risk group).