Newborns in intensive care: Apgar score predicts in fth minute

Apgar Score (AS) < 7 is a predictor of mortality. Survival is shorter in newborns, with AS 5min < 7 and the use of invasive mechanical ventilation (IMV). Thus, the objective of this study was to analyze whether maternal, obstetric, anthropometric, and postnatal variables of newborns admitted to the neonatal intensive care unit (NICU) may be associated with AS 5min < 7. If this score is a predictor of morbidity and mortality, and if factors most associated with the worse AS interfere with survival. This observational, retrospective, and quantitative study used a descriptive and inferential approach to analyze the medical records of patients of both sexes treated in the NICU of a tertiary hospital which is a recognized reference center of maternal and child health, during 2017. Data were collected to verify the relationship between AS values (AS 5min < 7 and AS 5min ≥ 7). AS 5min < 7 was associated with hypertensive disorders of pregnancy (HDP), premature rupture of the amniotic membrane, vaginal delivery, fetal trauma at birth, abdominal perimeter, and ventilatory support. Among these, HDP and the use of IMV were predictors of lower survival. Conclusion: AS 5min was associated with maternal, obstetric, anthropometric, and postnatal variables of neonates admitted to the NICU. Specic maternal and postnatal variables interfered with the survival of these newborns.


Introduction
Over 3 million children are born annually in Brazil. Approximately 16% of deaths occur per 1,000 live births. Neonatal death accounts for about 70% of deaths in the rst year of life. Prematurity is one of the most signi cant factors contributing to this high rate of neonatal mortality (approximately 7.2% of deaths in live births). The challenge is to reduce the infant mortality rate in this country [1].
The neonatal intensive care unit (NICU) is de ned as a convenient environment, focused on the care of atrisk newborns with various abnormalities, including congenital and acquired diseases, or those at risk of death. Premature newborns (de ned as those with a gestation period of fewer than 30 weeks and weighing less than 1 kg), or neonates who require invasive procedures, or those with highly complex clinical presentations, are also directed to the NICU. Immediate identi cation of all these conditions is essential for the maintenance and recovery of neonatal health [2].
The Apgar Score (AS) was developed in 1952 by the anesthesiologist, Virginia Apgar, as a scoring system that was used to standardize the evaluation of newborns after birth. This index has ve components that indicate the well-being of newborns: skin color, muscle tone, heart rate, breathing, and re exes. AS is an essential indicator despite the subjectivity of the evaluation. This scale converts clinical analyses into quantitative data and assisting the health team in making decisions to improve perinatal care [3].
For quanti cation, a score of 0 to 2 points is assigned. The result is re ective of the newborn's condition and should consider the following clinical factors: apnea, bradycardia, cyanosis, and hypotonia, among other conditions. The measurement is carried out at 1-minute, 5-minute, and 10-minute after birth.
However, if the newborn has a score lower than 7 in the rst minute (AS 1min < 7), the evaluation will be carried out at 5-minute intervals until the 20-minute interval\. This provides a convenient measure to report the life conditions of the newborn in the immediate postpartum period, as well as the potential need for resuscitation [3].
An AS score is less than 7 in the fth minute (AS 5min < 7) after birth is associated with low neurological and cognitive functions. Immediate identi cation of high-risk newborns may reduce perinatal morbidity and mortality [3,4]. If the AS is low and comorbidity such as bronchopulmonary dysplasia is present, there is an increased chance of delayed neuropsychomotor development in the premature neonate weighing less than 1500 g. This shows that the scale has great relevance in the prior identi cation of diseases and conditions associated with the neurological system [5].
AS is used clinically as a screening tool to identify newborns who require greater attention, close observation, and/or intervention. Factors associated with AS 1min and AS 5min < 7 should be analyzed in clinical research to gain a better understanding of the different aspects and also, the negative implications [6]. Information on how these scores may indicate morbidity and mortality of newborns is scarce.
A low AS on this scale (AS 1min and AS 5min < 7) is correlated with increased mortality. This aspect has stimulated much research [7]. Therefore, understanding the clinical importance of a low AS has been stimulated and further research to analyze the possible contributing factors is needed [8].
It is important to emphasize that the in uence of these factors has been rarely studied in Brazil. Pediatric health teams need more information to assist in clinical practice. Therefore, this study aimed to analyze whether maternal factors, obstetric factors, anthropometric data, and postnatal variables of neonates admitted to the NICU are associated with AS 1min and AS 5min < 7. This study also aimed to analyze whether this score is a predictor of morbidity and mortality and whether factors associated with the worst AS interfere with survival.

Ethical Aspects
The research was conducted after approval by the Research Ethics Committee, n. 2,442,015. The design was performed in accordance with the ethical principles provided in Resolution 466/12 of the National Health Council of Brazil and was conducted as per the Declaration of Helsinki.

Study Design
This study was designed as an observational, retrospective and quantitative study. Descriptive and inferential approaches were used.
Characterization of the place and period of study The study collected data from the medical records of patients treated at Santa Casa de Misericórdia de Belém, PA, Brazil, during 2017. The hospital is a tertiary reference center for maternal and child health.

Participants
For this study, the researchers had access to a total of 651 records collected in 2017 by a multidisciplinary team at Hospital Santa Casa de Misericórdia de Belém, PA. These records were all randomly organized. Each medical record was assessed to determine whether all the necessary items were correctly lled in and written legibly before inclusion for analysis. The study involved neonates of both sexes admitted to the neonatal intensive care unit (NICU).

Sampling
Sampling was probability-based. It was a simple random sample.

Sample
Data from 651 medical records were initially collected. Of these, 240 were selected after considering the inclusion and exclusion criteria. The minimum number of 217 medical records (AS 5min < 7: n=65; AS 5min ≥ 7: n= 152) was needed for the analysis, based on sample size calculations and pilot data from this study. Analyses were performed using the odds ratio (OR: 2.3199). The association between the use of invasive mechanical ventilation (IMV) and the values of neonates with AS 5min < 7 and AS 5min ≥ 7 was analyzed. For this calculation, the following parameters were established: one-tail, proportion p2: 0.67, relation of allocation N2/N1: 0.43, error α = 0.05, and β = 0.2.

Exclusion Criteria
We excluded patients with AS 1min ≥ 7 and incomplete medical records that prevented data analysis.

Inclusion Criteria
This study included the medical records of neonates who presented with AS 1min ≤ 7 and AS 5min < 7 and ≥ 7. The medical records included were categorized into two groups: AS 5min < 7 and AS 5min ≥ 7, for comparison between the factors, analyzed for the primary outcomes.

Data Collection
For data collection, we used a form elaborated by the authors, including maternal factors, obstetric factors, and anthropometric and postnatal data of the newborn. After completing the form, all data were tabulated and compared to verify the relationship between the values, AS (AS 5min < 7 versus AS 5min ≥ 7), and the different factors.

Primary Outcomes
The maternal factors analyzed were gestation time, number of deliveries, occurrence of abortion, number of pregnancies, absent prenatal care, gestational complications (leukorrhea, hypertensive disorders of pregnancy [HDP], anemia, urinary tract infections [UTIs], premature labor, premature rupture of membranes, and sexually transmitted infections [STIs]).
The obstetric factors studied were amniotic uid (clear with or without lumps, thick, thin, or bloody meconium), type of delivery (cesarean or vaginal), use of spinal anesthesia, fetal presentation (cephalic, pelvic, or umbilical cord around the fetal neck), fetal trauma at birth, single delivery, and amniotic membrane condition (intact or ruptured).

Statistical Analysis
After verifying the normality of the data via the Lilliefors test, they were presented as means and standard deviations (parametric data) or medians with interquartiles ( rst and third) (non-parametric data). To verify intergroup differences, non-paired t-tests (parametric data) and Mann-Whitney (nonparametric data) tests were used. Categorical variables were presented as absolute frequencies. The chi-squared test with Yates's correction was used to analyze the association between categorical variables. To quantify the level of association, odds ratios (OR) with 95% con dence intervals (95% CI) were used. Subsequently, the data most associated with the worst AS were submitted for survival analysis. For the analysis of life expectancy, the calculation was performed considering the life period from birth to the occurrence of the event corresponding to death. In addition, the Log-rank, Breslow, and Tarone-Ware tests were used to analyze each independent variable along with the Kaplan-Meier survival curves.
Male neonates were more prevalent in both groups (AS 5min ≥ 7: n = 100; AS 5min < 7: n = 43). Table 3 presents anthropometric data of the neonates. The abdominal perimeter of the neonates with AS 5min < 7 was greater than that of the neonates with AS 5min ≥ 7. The clinical variables in the postnatal period are presented in (Table 4). Neonates with AS 5min < 7 were associated with the use of CPAP and IMV. Neonates with higher AS remained longer in the NICU (AS 5min ≥ 7: 15 ; AS 5min < 7: 06 [2-24.75]; Mann-Whitney test p = 0.0215). Neonates with AS 5min < 7 were twice as likely to die than neonates with AS 5min ≥ 7. According to the analysis of the survival curve, we observed that differences exist between newborns admitted to the NICU of mothers who presented HDP (A) and who made use of IMV, with shorter survival in patients with AS 5min < 07 (Fig. 1). Lastly, the other variables did not differ between the groups.

Discussion
The Apgar score contributes to the improvement of perinatal care by converting clinical analyses into quantitative data [3]. However, studies are needed to verify the clinical implications. In this context, this study found that neonates with AS 5min ≥ 7 were associated with the presence of gestational leukorrhea and a longer stay in the NICU. Furthermore, AS 5min < 7 is associated with HDP, premature rupture of the amniotic membrane, vaginal delivery, fetal trauma at birth, abdominal perimeter, and the use of ventilatory support. Among these, HDP and use of IMV were identi ed as predictors of lower survival.
However, we observed that mortality was higher in neonates with AS 5min < 7.
AS 5min ≥ 7 was associated with the maternal factor, gestational leukorrhea. Leukorrhea refers to the presence of vaginal discharge of liquid, except blood, through the vagina. 9 In pathological cases, the main factors are STIs, young women, non-stable marital relationships, multiple sexual partners, sexual intercourse without using a condom, and the black race [9]. The results of our study showed that STIs and age were not different ndings in our study.
HDP was related to AS 5min < 7. HDP refers to a diastolic blood pressure of at least 90 mmHg or systolic blood pressure of at least 140 mmHg over a period of at least 6 h. [10][11][12]. This relationship has been observed in previous studies [10][11][12][13]. The presence of polycythemia is a determining factor for the higher incidence of birth asphyxia [10]. HDP may impair uteroplacental circulation, generate an imbalance in maternal homeostasis, facilitate pathophysiological changes in the placenta, and increase the risk of fetal hypoxia due to vascularization de ciency, [10,14]. thereby resulting in lower survival, as observed in this study.
Premature rupture of membranes (PROM) was another maternal factor related to AS 5min < 7. This variable was associated with all preterm births [15,16]. The presence of this maternal factor in premature neonates with low AS was associated with an increased mortality [17].
Vaginal delivery and fetal trauma at birth were associated with AS 5min < 7, as con rmed in the literature [18,19]. Fetal trauma at birth is de ned as any sign or trauma found in the newborn after birth. The presence of fetal trauma at birth may be related to obstetric and demographic factors, or maybe related to maternal anatomical characteristics [18,19].
The abdominal perimeter was higher in neonates with AS 5min < 7. Anthropometric data contributed positively to a general analysis of this condition in a newborn [20]. Abdominal circumference after birth has been related to the resistance of the anterior abdominal wall, phase of breathing, and amount of fat [21]. These factors can directly in uence ventilatory mechanics.
Moreover, AS 5min < 07 was associated with the use of ventilatory support, and IMV was a predictor of lower survival in the rst days of life. AS 5min < 07 may suggest a higher probability of perinatal asphyxia [22,23]. In this way, several maneuvers were used to reverse this condition including CPAP and IMV.
In addition, this study found that AS 5min in neonates with AS 1min < 7, is directly related to newborn mortality. Previous studies [3,24,25].. analyzing only AS 5min corroborated with the results of this research. However, the survival of the newborn seems to be directly related to immediate postnatal conditions [3,24,25]. AS 5min ≥ 7 was associated with a longer length of stay in the NICU. Concerning the longer length of stay in the NICU, the longer survival presented by these neonates should also be considered.
Thus, we believe that there is a need for professional follow-up during the gestational, perinatal, and postnatal periods. Prenatal care is essential because it minimizes the possibilities of complications during pregnancy, and enable clinical and laboratory ndings to be added to the standard clinical evaluation [26]. The follow-up of the newborn during other developmental phases may further contribute to guiding clinical practice. The relevant factors found in this study should also be considered.

Conclusion
AS 5min ≥ 7 was associated with the presence of gestational leukorrhea and prolonged stay in the NICU. In addition, it was observed that HDP, vaginal delivery, fetal trauma at birth, and premature rupture of the amniotic membrane are predictors of AS 5min < 7, indicating a greater need for ventilatory support.
Furthermore, lower scores at AS 5min were predictors of mortality. Finally, we conclude that survival is lower in newborns with AS 5min < 7, born to mothers with HDP, and the use of IMV. Consent for publication: Not applicable