European Journal of Cardiovascular Medicine

The intrapartum period is one of the most necessary periods for foetus when fetoplacental circulation is challenged to the highest degree (1).  Uterine contractions are associated with a significant decline in uterine artery flow velocity leading to a decrease in placental perfusion, causing foetal hypoxia (2). Foetal hypoxia can result in a neonatal squeal, including neurological injury, seizure, and death. The majority of cases of intrapartum hypoxia occur in pregnancies with no antenatal risk factors, predicting intrapartum foetal complications difficult.

The cerebroplacental ratio (CPR) is emerging as a significant predictor of adverse pregnancy outcomes (3). It is an obstetric ultrasound tool that reflects the redistribution of cardiac output to the cerebral circulation resulting from hypoxia and increased placental resistance (4). The CPR is calculated by dividing the doppler indices of MCA by the umbilical artery (MCA PI/UA PI). The CPR reflects a mild increase in placental resistance with a mild reduction in foetal brain vascular resistance (5) . CPR is better predictor of adverse perinatal outcome than the MCA PI & UM PI .

In Uncomplicated pregnancies without symptoms of abnormal placental function, a decreases in MCA PI values may constitute an early manifestation of adaptive changes even before any alteration in UA appear (6) .

Even AGA foetuses with a low CPR ratio at term are at increased risk of compromise during labour leading to an increased rate of obstetrics interventions and neonatal morbidity and mortality (7).

Foetuses with abnormal CPR that are AGA have a higher incidence of foetal distress in labour, requiring emergency Caesarean delivery, a lower cord pH, and an increased admission rate to the new born intensive care unit (NICU) compared with foetuses with normal CPR (8).

Foetal hypoxia activates several defence mechanisms, such as modification of foetal heart rate (FHR), increase in blood pressure, and redistribution of blood to the heart, brain, and adrenal glands. Low oxygen partial pressure (pO2) leads to cerebral vasodilation and a fall in vascular resistance, which results in a decrease in middle cerebral artery resistance index (MCA RI) values (9). About 50% of foetal deaths occur in low-risk mothers without apparent cause. Although many technologies have been developed for monitoring foetuses in high-risk mothers, we should not underestimate the foetuses of low-risk mothers as they are equally precious.

CPR is a better predictor of adverse perinatal outcomes than the MCA PI and UA PI. Another investigation that played a role in perinatal mortality was continuous cardiotocography (CTG), but its use has been reduced because of its low sensitivity to predict adverse perinatal outcomes (10).

It is a Prospective observational study. All low-risk term Pregnant women admitted to the labour room in the department of Obstetrics and gynaecology, MGMMC, and M.Y. tertiary care teaching hospital, Indore, India from October 2021 to October 2022. Approval of the Institute Ethics Committee (EC/MGM/OCT-21/10) was obtained before beginning this investigation and informed consent was obtained from all participating patients. 150 Patients were selected based on the following selection criteria: -

 INCLUSION CRITERIA

 Term pregnancy, Spontaneous labour, Low risk pregnancy

 EXCLUSION CRITERIA

1. Patients who are in active labour.
2. Women with High-risk pregnancy like Malpresentation, IUGR, PROM, Previous cesarian section, Age less than 18 yrs., High BMI and Medical Illness like Hypertensive Disorder, DM, CLD, CKD, Hypothyroidism, Cardiac disease etc. will be excluded from this study.

Pregnant women attending Obstetrics and Gynaecology outpatient department in MGMMC and M.Y. group of hospital Indore, fulfilling the inclusion and exclusion criteria, were considered and included after collecting the informed consent. A total of 150 women were included in the study. All participants were provided with a study information sheet and were allowed to ask questions about the study and their participation. Written informed consent was then obtained.

Demographic details, obstetric history, examination findings, and investigation results of women enrolled were recorded. Gestational age was determined according to the last menstrual period, which was agreed with the first-trimester ultrasound examination.

The cerebroplacental ratio was measured at the latent phase of labour. The patients were asked to lie in a semi recumbent position in the labour room. The CPR was measured by a trained medical practitioner who noted the UA PI and the MCA PI using the Doppler USG in between uterine contractions (ascertained by tocography and uterine palpation). The Doppler was placed at an angle of insonation below 30° when there were no maternal and foetal movements. Once three consecutive waveforms were traced, based on The International Society on Ultrasound in Obstetrics and gynaecology recommendations based on the UA PI and the MCA PI, the CPR was calculated.

Based on the CPR the study subjects are grouped into A and B, where patients with CPR <1 are grouped as A and patients with CPR > 1 are grouped as B. The patient are followed to determine the relationship between CPR and fetal outcome.

The adverse perinatal outcome such as,

• CTG abnormalities,
• Meconium-stained liquor (MSL),
• NICU admission,
• Low Apgar score,
• Need for resuscitation, and
• Neonatal deaths were noted in both the groups.

The mode of delivery (spontaneous vaginal delivery, caesarean delivery, and instrumental delivery) was also noted in both the groups. The diagnostic accuracy to predict adverse perinatal outcome was evaluated based on Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

STATISTICAL ANANLYSIS

The Excel and SPSS (SPSS Inc, ver. 27 Chicago) software packages were used for data entry and analysis. The results were averaged (mean + standard deviation) for each parameter for continuous data and numbers and percentage for categorical data presented in Table and Figure.

The continuous variables were expressed in terms of mean and S.D and nominal/ ordinal variables are expressed in percentage.Mann–Whitney U test was used to compare the mean. Significance was assumed at a p-value of less than 0.05. Proportions were compared using Chi-Square and Fisher’s Exact test of significance. Significance was assumed at a p-value of less than 0.05.

Table 1 : Baseline characteristic of the study subjects:-

In our study among the 150 study participants, the participants were grouped as A and B, patients with CPR < 1 are grouped as A and patients with CPR > 1 are grouped as B. On analysing the baseline characteristics of the study participants are shown in table 1.  The mean gestational age among the participants in group A was 275.07 ± 6.61 days and 273.47 ± 5.88 among group B. In our study the mean BMI was higher among the participants belonging to group A with 24.95 ± 3.13 and 23.58 ± 2.76 among participants in group B.  In our study the mean UAPI was higher among the participants belonging to group A with 0.91 ± 0.32and 0.85 ± 0.08 among participants in group B. The mean MCA PI was lower among the participants belonging to group A with 1.15 ± 0.46 and 1.46 ±0.26 among participants in group B.The CPR was lower among the participants belonging to group A  with 0.74 ± 0.14 and 1.77 ± 0.28  among participants in group B.  On applying Mann-Whitney U test to compare the mean and Chi-square test to compare the proportion, there was significant association (p <0.05) in relation to the MCA PI and CPR.Table. No 1 : Baseline characteristic of the study subjects:-

Table 2: Distribution of mode of delivery in relation to the CP ratio.

Table 2 shows that on comparing group A & B in relation to the mode of delivery, majority 130 (95.59%) of the patients in the group B had Vaginal delivery, majority 7 (50%) of the patients in group A delivered by caesarean section. On applying Chi-square test, there was a significant association between CP ratio and the mode of delivery, were patients with CPR < 1 have a higher chance of caesarean section and patients with CPR > 1 have increased chance of spontaneous vaginal delivery.

Table 3 : Distribution of adverse perinatal outcome in relation to the CP ratio among the study subjects.

In our study majority 13 (92.86%) of the patients with adverse perinatal outcome had CPR <1 and 16 (11.76%) with CPR > 1 had adverse perinatal outcome.

Table 4: CPR as a predictor of adverse perinatal outcome

In our study the by using the CPR as predictor for perinatal outcome, the sensitivity was 92.86%, specificity was 88.24%, Positive predictive value of 44.83% and negative predictive value 88.67% indicating that the patients who had normal CPR had no adverse outcome.

Table 5: Distribution of adverse perinatal outcome in relation to the CP ratio among the study subjects.

On comparing the distribution of various adverse perinatal outcome between group A & B, majority 11 (78.57%) of the patients with CTG abnormalities belonged to group A and 2 (1.47%) group B.

Most 1 (%) of the patients with low birth weight belonged to group A and 3 (%) group B.  On comparing the APGAR score at 1 min and 5 min, majority of the patients with poor APGAR score belonged to group A compared to group B.50% of the patients in group A had MSL compared to 4% in group B,  Majority of the patients in group A required NICU admission, neonate requiring resuscitation, developed perinatal complication compared to group B. The mean duration of NICU admission for group A was 78.3 ± 2.34 hrs and 15.2 ± 8.14 hrs for group B.

Table 6 : Distribution of diagnostic accuracy of CPR by area under curve and perinatal outcome

On measuring the diagnostic accuracy of the CPR, in predicting the adverse perinatal.CPR is a good predictor for NICU admission (0.822) and CTG abnormality (0.81), Fair predictor for patients requiring resuscitation (0.738), MSL (0.715).CPR is a poor predictor for poor APGAR score.

The role of doppler in fetal surveillance has been used for two-three decades. Currently it has been used in the detection of placental insufficiency, where the changes in the flow of blood is altered. Multiple studies have been done among patients with high-risk pregnancy, the present study is done among low-risk term pregnancy, where the CPR is measured at the early stage of labor. A total of 150 pregnant women were analyzed to correlate the cerebroplacental ratio with the fetal and maternal outcomes. Out of the 150 pregnant women, the participants were grouped as A and B, patients with CPR < 1 as A, and patients with CPR > 1 as B.

On analysing the baseline characters among the study subjects

Correlation of CP ratio with mode of delivery

On comparing the mode of delivery in relation to the CPR, the number of women who underwent caesarean section was significantly in a higher ratio compared to patients with the higher CPR ratio, in the study conducted by Kamalarani AE et al. (55) on correlating between the CPR and the caesarean section there was significant (p=0.01) association between CPR<1 and LSCS. Which was in concurrence to our study there was a significant association (p= <0.001) between CP ratio and the mode of delivery, were patients with CPR < 1 have a higher chance of caesarean section and patients with CPR > 1 have increased chance of spontaneous vaginal delivery. The most common indication for LSCS among CPR <1 was foetal distress which was in concurrence to the study conducted by Kamalarani AE et al. Gramellini et al (45) and Arias et al. (60) were the indication for LSCS was foetal distress and it was found  higher among patients with abnormal CPR.

Kamalarani AE et al. reported that the most common indication for LSCS was foetal distress, and it was found higher 31.25% among patients with abnormal CPR compared to 10.14% among patients with normal CPR.

1. Anand et al. in the study reported that the patients with CPR≤1 had ninefold increase rate of caesarean section for intrapartum foetal compromise. Tomas prior et al, in his study on measuring the CPR among patients delivered by spontaneous vaginal delivery and caesarean delivery, it was found that the patients delivered by caesarean section had lower CPR compared to patients delivered by spontaneous vaginal delivery.

Correlation of CP ratio with MSL baby

In our study majority 50% of the patients with CPR <1 had MSL compared to 4% of the patient with CPR >1 and on correlating there was a significant association.Singh K, et al. in the study reported that majority of the patients with normal CPR had a clear liquor, on analysing the patients with abnormal CPR, there was significant (P <0.00001) increase in the MSL patients. The study reported that the patients with abnormal CPR had a 6 times higher chance of MSL compared to patients with normal CPR.

Correlation of CP ratio with NICU admissions : In our study majority of the patients with abnormal CPR had NICU admission and they were significantly associated. Singh K, et al. in his study reported that there was a significant association and the risk of patient with abnormal CPR getting admission is 22 times higher than the patients with normal CPR.

Correlation of CP ratio with the need for resuscitation : Singh K, et al. in the study, reported  that majority of the patients with abnormal CPR had an increased need of resuscitation, it was found that patients with abnormal CPR had an 18 fold increased rate for resuscitation.In our study there patient with abnormal CPR had an increased need for resuscitation and it was significantly associated (p <0.001).

Correlation of CP ratio with Abnormal CTG : CTG abnormalities (classified as either suspicious or pathologic according to NICE guidelines) when compared with infants, it was found patients with abnormal CPR had an abnormal CTG compared to the patients with normal CPR, on correlating the abnormal CTG with the CPR, there was a significant association between the abnormal CPR and abnormal CTG. Singh K, et al. in the study reported that the patients with abnormal CPR has an 13 folds increase of abnormal CTG.

Correlation of CP ratio with Adverse perinatal outcome : On comparing the adverse perinatal outcome in relation to the CPR, majority of the patients with abnormal CPR, had adverse perinatal outcome compared to normal CPR which was in concurrence to the present study. In our study CPR was found to be good method to predict the adverse perinatal outcome in low-risk, term pregnancy if detected in the early stage of labor

In our study entitled “A Prospective Study of Cerebroplacental Ratio Assessment in Low-Risk Term Pregnancy and its Effect on Maternal and Fetal Outcome” it was found there was a significant association between the abnormal CPR and the adverse perinatal outcome. Our study has proved that even women with low-risk term pregnancy must be monitored, measuring CPR at the third trimester would help us to predict and reduce the adverse perinatal outcome. The CPR was found out to be a good indicator to predict the adverse perinatal outcome with the sensitivity of 92.86%, specificity 88.24%, positive predictive value of 44.83% and negative predictive value 88.67% indicating that the patients who had normal CPR had no adverse outcome.

The CPR is an efficient marker both for detection and follow up of early – stage placental insufficiency during the third trimester. Among the adverse perinatal outcome CPR is a good predictor for NICU admission (0.822) and CTG abnormality (0.81), Fair predictor for neonates requiring resuscitation (0.738) and MSL (0.715).

Since the use of USG doppler is a non-invasive and cost-effective diagnostic technique, it can be used as a routine third-trimester antenatal check-up; since CPR has a high specificity, it could help us to triage the patients and helps the clinician to provide timely intervention , this in turn reduce perinatal morbidity & mortality and prevent neonatal  NICU admission . Assessing CPR can be a useful tool for counselling the couple and taking informed decisions about the mode and place of delivery.

In the peripheral centre, CPR helps in providing decision for timely referral to tertiary care centre for intrapartum monitoring with NICU admission. With high specificity of CPR , it is likely that those having a normal CPR will have very less chance of adverse perinatal outcome , and therefore , their delivery can be conducted at peripheral center and those with low CPR should be timely referred to higher center where there are facilities for meticulous fetal monitoring during the intrapartum period with availability of NICU Care.

CONFLICT OF INTEREST:  They authors declare that they have no conflict of interest.

ETHICAL APPROVAL:  Institutional ethical committee clearance was obtained for study . all procedure performed in studies involving human participants were in accordance with the ethical standards of the institutional and /or national research committee.

INFORMED CONSENT:  Informed consent was obtained from all individual participants included in the study.  

FUNDING:  This study was not funded by any individual or agency.

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