Neonatal Outcome in High Risk Pregnancies Based on Umbilical Arterial Blood Gas Analysis

Research Article

J Fam Med. 2022; 9(7): 1317.

Neonatal Outcome in High Risk Pregnancies Based on Umbilical Arterial Blood Gas Analysis

Mamta1, Ghanshyam Chaudhary2, Manisha Verma3*, Aradhana Kankane4, Vidya Chaudhary5

1Senior Resident Pediatrics, ESIC Hospital, Pandepur, Varanasi, UP, India

2Department of Pediatrics, Government Medical College, Orai, Jalaun, UP, India

3Assistant Professor, Department of Pediatrics, Dr. Ram Manohar Lohia Institute of Medical Sciences, India

4Associate Professor, Department of Pediatrics, Maharani Laxmi Bai Medical College, Jhansi, UP, India

5Associate Professor, Department of Obstetrics and Gynaecology, Government Medical College, Orai, Jalaun, UP, India

*Corresponding author: Manisha Verma, Assistant Professor, Department of Pediatrics, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, UP, India

Received: September 08, 2022; Accepted: October 21, 2022; Published: October 28, 2022


The purpose of this study is to evaluate the correlation between umbilical arterial blood gas and short term outcome of the neonates born. This prospective observational cohort study was carried out at Department of Paediatrics, MLB Medical College, Jhansi on 120 term neonates delivered by caesarean sections or normal vaginal delivery of high risk mother based on Neonatal Resuscitation Program (NRP) between July 2017 to July 2018. All neonates were divided into two groups: 1) Group I (52 cases) consists of neonates with umbilical cord pH less than 7.2, whereas Group II (68 cases) consists of neonates with umbilical cord pH more than 7.2.

Male babies and LSCS delivery were higher in both groups. The most common risk factors in mother are anemia (26%) and MSL (23%). All the cases were full term babies and have normal birth weight. Mean PO2 level was 11±6 and in group II it was 14±8. Mean PCO2 in group I was 63.7±13.7 while in group II it was 52.1±7.9. Mean bicarbonate was 21.36±3.54 and in group II it was found to be 24.13±3.25. On statistical analysis difference between pH, PCO2, PO2, BE and bicarbonate was significant. In group I, neonates required resuscitation in 57.69% (30 out of 52 cases), but in group II, only (10.29) (7 out of 68) cases required resuscitation. In group I, 48.07% (25 of 52) newborns were admitted to the NICU, whereas 5.88% (4 of 68) neonates in group II were admitted to the NICU. Encephalopathy is observed in 15 instances (28.85%) in Group I, but only 4 cases (5.88%) in Group II. HIE symptoms were frequently seen in the initial hours or days following delivery. Convulsion occurred in 11 instances (21.15.0%) in Group I, but only 3 cases (4.41%) in Group II. Convulsive disorders as sign of moderate encephalopathy had been presented more in neonates who had acidosis in 24 to 48 hours after birth. In group I, 26 cases (50.0%) had delayed in attaining oral feed until an hour, but in group II, only 4 cases (5.88%) cases had delay in attaining oral feed until an hour. The statistical association between delayed attainment of full meal and infant pH is significant. HIE is significantly higher in group 1. The average hospitals stay among academic newborns in Group I was 3.9613.199 days. The length of hospital stray in academic newborns exhibited an inverse connection with umbilical cord pH. In group II, the average length of hospital stay is 2.151.479 days. When compared to group II, group I experienced a considerably longer hospital stay. At 1 and 5 minutes of birth, a new-born with cord blood pH <7.2 had an APGAR score of 5.60±1.963 and 7.88±1.437, whereas a baby with cord blood pH >7.2 had an APGAR score of 8.70±0.964 and 8.70±0.964. According to statistical study, the APGAR score is significantly related to the pH of the cord blood.

Umbilical cord blood ABG has been conducted as a definitive factor for fetus evaluation. The pH of umbilical cord blood is the best current criteria for diagnosing foetal hypoxemia during labour and determining appropriate postnatal care decisions.

Keywords: Neonatal; High risk pregnancies; Outcome; Umbilical arterial blood gas; Analysis; India


According to the WHO, around 9 million neonates suffer from birth asphyxia each year, 1.2 million of them die [1], and the same number suffers from severe repercussions such as cerebral palsy, epilepsy, and delayed developmental milestones.

Numerous researches have been conducted to identify the risk factors and how intrapartum hypoxia affects the health of term babies [2]. It is widely acknowledged that labour has a relatively small role in the genesis of cerebral palsy, even after term delivery [3]. The majority of estimations indicate that only up to 15% of children who are impacted are the result of labour. However, these incidents are seen to be theoretically preventable, they frequently result in litigation, and efforts to prevent them result in greater intervention and the use of significant resources.

Fetal hypoxia is addressed in this intrapartum cerebral palsy prevention method. "The monitoring of newborns in labour seeks to discover hypoxia before it is adequate to lead to harmful acidosis and long-term neurologic consequence for the baby," according to the National Institute for Health and Clinical Excellence (NICE) [4]. This has included Electronic Foetal Monitoring (EFM) in high-risk pregnancies, and intermittent auscultation in low-risk pregnancies with a fallback to EFM in the event of anomalies. If EFM is abnormal, foetal acidemia should be assessed by scalp sample. By convention, although the data on the relationship between scalp, pH and outcomes is restricted largely to Apgar scores, a normal level of scalp pH is >7.24 at <7.20 urgent delivery is advised [5]. Identification and prevention of fetal acidemia is therefore the main aim of intrapartum fetal monitoring, so that’s why the cord pH is considered a crucial outcome measure.

Suspected fetal distress detected by cardiotocography or nonstress tests and by presence of meconium stained liquour have been the most common indication for caesarean section for the past few decades. Fetal distress may be defined as a physiological state in which there is metabolic acidosis secondary to hypoxia [6]. When CTG was introduced in 1970, it was hoped that this technique would reduce the incidence of cerebral palsy and mental retardation by 50% [7]. Disappointingly, the results of randomized trials showed little or no benefit with respect to long term neurological outcome despite widespread use of CTG. It was found that the CTG results in no long term benefit in neonatal outcome; on contrary it results in fourfold increase in caesarean section rates [8,9]. Various studies implicate that CTG interpretation is inconsistent inaccurate, may fail to predict early neonatal outcome and is subject to influence by the medicolegal climate [10,11]. Furthermore the significance of meconium in amniotic fluid is also widely debated subject [12]. Traditionally meconium has been viewed as a sign of impending or ongoing fetal compromise, however some investigators believe that it is not associated with fetal hypoxia, acidosis or fetal distress [13]. Many babies born with meconium stained amniotic fluid have normal umbilical artery pH, so recent literature tends to disregard the importance of intrapartum meconium as a sign of fetal hypoxia [12], hence clear liquour is an indication of fetal well-being and meconium staining of amniotic fluid is not always associated with an ill infant [14].

There was also a significant relation between umbilical cord pH and low Apgar score with the incidence of selective neonatal outcome like NICU admission, need for resuscitation. The most widely used method for assessment of neonatal outcome is Apgar score which is semiobjective, alone is not a reliable indicator for intrauterine asphyxia or immediate neonatal mortality. So umbilical cord blood pH is the best available criteria for detecting fetal hypoxemia during labour and making appropriate decisions about care after birth.

Perinatal hypoxia, ischemia, asphyxia, refers to relative lack of oxygen, blood flow, gas exchange to foetus or new-born.

Perinatal or neonatal depression refers to condition of the infant on physical examination in immediate postnatal period (first hour of life). The infant may show muscle hypotonia, depressed mental status, disturbed respiratory and cardiovascular function [15].

Fetal acidemia is defined as umbilical artery pH less than 7.2, significant acidemia if pH less than 7, some authors defined significant acidemia 2SD below the mean for given population [16].

The diagnosis of intrapartum asphyxia mandates the presence of severe cord blood acidemia, and thus normal values refute this diagnosis. Umbilical blood gas parameters can be used to assess neonates in pregnancies complicated by meconium stained amniotic fluid in which tracheal visualization, intubation and suctioning may lead to low Apgar score that may be wrongly attributed to new-born asphyxia.

As a general rule, adverse events are observed more when pH is on lower side or base deficit is high. These babies would have a low apgar usually. Adverse outcomes mostly noticed in babies are low Apgar, NICU admission, need for assisted ventilation, delay in attained full feeds. Very adverse outcomes like demise, encephalopathy, and organ system failure (though rare) are seen in cases with very low pH almost less than 7. Now a days, very adverse outcomes are observed only in a few numbers, this might be due to the interference of an experienced pediatrician during resuscitation in an asphyxiated newborn or opting for an emergency caesarean section for uteroplacental insufficiency or fetal indications (tachycardia or deceleration). This hinders degree of insult due to asphyxia at a considerably early stage.

When a fetus is subjected to a massive perinatal hypoxic ischaemic insult, fetus may suffer sufficient damage to cause intrauterine death and still birth. In less severe non-fatal cases, prolonged or severe intrauterine hypoxia may lead to serious neonatal complication like hypoxic ischaemic encephalopathy, cerebral palsy, impaired myocardial function, seizures, intraventricular haemorrhage and delayed development. Cerebral palsy is thought to occur more frequently at an arterial cord blood pH <7. However these criterionshave been derived through consensus and not through summary of evidence leading to clinical uncertainty. Since the association between umbilical cord blood pH at birth and perinatal outcome have been derived through consensus and not through evaluation of evidences. It is therefore necessary that validating of this association be supported with high quality evidence.

Short term outcome - need to resuscitation, admission to newborn services and/or NICU, convulsion, delay in oral feeding and duration of hospital stay. Low arterial cord pH was significantly associated with perinatal and long term neonatal outcomes like mortality, hypoxic ischemic encephalopathy, intraventricular haemorrhage or periventricular leukomalacia and cerebral palsy [2]. No such study has been conducted in this part of India, though there is high prevalence of LSCS, birth asphyxia and high rates of SNCU admission. As a result, this study attempts to correlate umbilical arterial blood gas parameters with the short-term outcome of newborns.


This prospective observational cohort study was carried out between July 2017 and July 2018 at the Department of Paediatrics, MLB Medical College, Jhansi, on all term neonates delivered by cesarean section and normal vaginal birth to a high risk mother based on the Neonatal Resuscitation Programme (NRP). The ethics committee approved the study, and parents provided informed consent. There were 120 neonates in all, divided into two groups: 1) Group I (52 cases) consist of neonates with umbilical cord pH less than 7.2, whereas Group II (68 cases) consist of neonates with umbilical cord pH more than 7.2.

Inclusion Criteria

• Baseline fetal heart rate <110/mm, variability <5 bpm

• Meconium stained amniotic fluid.

• All high risk pregnancies

• Elderly primi (>30 years)

• Short statured primi (<l4Ocms)

• Malpresentation

• APH, threatened abortion

• Preeclampsia/eclampsia

• Anemia

• Twins, polyhydroamnios

• Previous still birth, IVD

• Elderly grand multipara

• Prolonged pregnancy >14 days of EDD

• H/o previous LSCS or instrumental delivery

• Pregnancy associated with diseases like CVS, kidney, diabetes,

• TB, liver diseases.

Exclusion Criteria

• Prenatal infection, any major congenital anomaly.

• Intrauterine fetal death

• Patient refusal

Statistical Analysis

Data will be analysed by Epi info version 18, x2 test, Mann- Whitney and Spearman test will be used. p less than 0.05 was considered as being significant.

Sample Collection & Investigations

An about 20-cm piece of cord must be separated between two sets of two clamps immediately after birth, ideally before the baby's first breath. The acid-base characteristics of clamped cord blood remain stable at room temperature for 60 minutes after being separated from maternal/neonatal circulation. To get blood for examination, the cord section is first cut between the two clamps at either end, allowing the clamped segment to be removed from the baby's close vicinity. Needle aspiration is used to collect arterial blood into a preheparinized syringe. Within 30 minutes of birth, the samples will be analysed by an ABG analyzer (Gem Premier, USA).

Blood was drawn from the cord and placed in the analyzer. The analyzer draws blood into a measuring chamber equipped with an iron selective electrode (i.e. electrodes that sensitive only to measurement of interest).

The pH electrode compares an electrode tip potential to a reference potential; the resultant voltage is proportional to the concentration of hydrogen ions, [H+].

The pCO2 electrode is a pH electrode with a Teflon or silicone rubber CO2 semi permeable membrane covering the tip. CO2 combines with H20 in the space between the membrane and the electrode tip to produce free hydrogen ions in proportion to the partial pressure of CO2. The voltmeter, although actually measuring [H+], is calibrated in pCO2.

For pO2, oxygen permeates a polypropylene membrane and reacts chemically with a phosphate buffer. The O2 combines with water in the buffer, producing current in proportion to the number of oxygen molecules. The current is measured and expressed as partial pressure of oxygen.

The blood is immediately ejected into a trash receptacle after measurement, and the sample passage is cleaned in preparation for the next sample. The results can be printed, displayed, or sent to the Laboratory Information System.

Short Term Outcomes Were Noted

• Need to Resuscitation: Resuscitate neonates with meconium stained amniotic fluid, lack of spontaneous or effective respiratory effort and lack of appropriate muscular tone.

• Need to being admitted to neonatal ward or NICU: Neonates who required positive pressure ventilation will be admitted to SNCU and/or NICU.

• Convulsion: Diagnosis of convulsion made by clinical observation. All neonates with convulsion will be admitted and treated in neonatal ward or NICU.

• Encephalopathy: Any asphyxiated neonate with neurologic signs and symptoms defined and classified based on the Sarnat and Sarnat staging system.

• Delayed Start of Oral Feeding and/or Feed Intolerance: Because of feed intolerance or respiratory distress, oral feeding started after stabilization. All neonates admitted to the NICU will be kept NPO and on IV fluid till stabilization.

• Hospital Stay: This period is calculated from birth to discharge and declared as days.

• Death: Any cases of death in both groups will be recorded.

• Babies were followed for maximum 28 days or 7 days after discharge.


This prospective observations cohort study was conducted on 120 term neonates delivered by cesarean sections or normal vaginal delivery of high risk mother based on neonatal resuscitation program (NRP). 52 had a pH less than 7.2 and 68 had a pH more than 7.2 (Table 1).