Neonatal Morbidities in Late-Preterm Infants Compared with Term Infants admitted to an Intensive Care Unit and Born Predominantly by Cesarean Section

Jose Maria de A Lopes; Renata Bastos Lopes; Rovena Cassaro Barcelos; Fern; o Freitas Martins; Filomena B Mello

doi:10.4172/2376-127X.1000237

ISSN: 2376-127X

Journal of Pregnancy and Child Health

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Neonatal Morbidities in Late-Preterm Infants Compared with Term Infants admitted to an Intensive Care Unit and Born Predominantly by Cesarean Section

*Jose Maria de A Lopes^1, Renata Bastos Lopes¹, Rovena Cassaro Barcelos², Fernando Freitas Martins² and Filomena B Mello³**
¹Neonatology Maternity Perinatal, Brazil
²Neonatology Fernandes Figueira Institute Oswaldo Cruz Foundation, Brazil
³Hospital and Maternity Santa Joana- Sao Paulo Brazil
*Corresponding Author :	Jose Maria de A Lopes Neonatology Maternity Perinatal, Rua das Laranjeiras 445 Laranjeiras Rio de Janeiro, Brazil Tel: 552125581434 Fax: 552125589160 E-mail: jmlopes@perinatal.com.br
Received: March 12, 2016 Accepted: March 30, 2016 Published: April 12, 2016
Citation: Lopes JM, Lopes RB, Barcelos RC, Martins FF, Mello FB (2016) Neonatal Morbidities in Late-Preterm Infants Compared with Term Infants admitted to an Intensive Care Unit and Born Predominantly by Cesarean Section. J Preg Child Health 3:237. doi:10.4172/2376-127X.1000237
Copyright: © 2016 Lopes JMDA et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Abstract

Evidence supporting delayed cord clamping (DCC) in the premature newborn is increasing, yet in a level IV neonatal intensive care unit (NICU); DCC was not being consistently performed, and when it was there were noted variations in the absence of a standardized guideline. The objective of this quality improvement (QI) project was to develop and secure institutional approval of a DCC guideline for the premature newborn and increase knowledge of DCC among healthcare providers (HCPs). The design was a QI project using Rogers’ Diffusion of Innovations (DOI) Theory to guide the development of a DCC guideline. Educational in-services were conducted to increase knowledge of DCC and the components of the DCC guideline. A panel of nine experts including interdisciplinary HCPs from the NICU and the obstetrics department (OB) defined and approved the DCC guideline content. A convenience sample of 90 HCPs participated in the DCC educational inservices. The use of the DCC Guideline Development tool created from best evidence guided an interdisciplinary committee towards consensus and final approval of the DCC guideline. Eleven standardized DCC in-services were conducted with pretest-posttest knowledge surveys. Essential components of the guideline include a delay of 45 seconds before cord clamping, inclusion and exclusion criteria, thermoregulation interventions, and responsibilities of the NICU and OB team. In-service education of DCC and guideline was effective based on survey results. The DCC guideline and education of the HCPs seeks to translate best evidence into practice and standardize DCC implementation. Future plans include measuring retained knowledge, guideline adherence by the HCPs, and evaluation of clinical outcomes.

Keywords

Newborn; Preterm; Late preterm; Morbidity; Mortality; Prematurity

Introduction

Preterm birth is defined as birth before 37 gestational weeks. This type of birth substantially contributes to neonatal morbidities and is responsible for approximately 75% cases of neonatal mortality and >50% cases of long-term morbidities [1]. The incidence of preterm birth has increased in recent decades. The observed increase since 2005 was noted mainly in late preterm (34 0/7 weeks to 36 6/7 weeks). This new classification emphasizes that this group needs a higher level of attention than term infants [1-3].

In the US, premature birth has increased from 9.5% in 1981 to 12.7% in 2005, while in Europe, these values vary between 5% and 9% [1]. In South and Southeastern Brazil, the prevalence of premature births between 1978 and 2004 ranged from 3.4% to 15.0% [4]. Late preterm births comprised 71% of premature births [5]. When compared to term infants, late preterm birth cases more often require admission into the NICU due to a higher incidence of morbidities such as respiratory distress, higher need for intravenous fluids, and neurologic symptoms, and these cases are also associated with a prolonged length of stay [6-8].

Some obstetric practices that might have contributed to the increase in premature births include the growing tendency toward elective Csections,, mother or physician driven, birth at earlier gestational ages, the conduct related to preterm labor with recommendation for the use of tocolytics and antenatal steroids until 34th gestation week, as well as the increase in primary C-section rates, with consequent higher chance of repeated C-section. There is a particular concern with elective Csection on a scheduled date, as the estimated gestational age (GA) is based on postmenstrual period and first trimester ultrasound findings, both of which have a margin of error of 1-2 weeks. Thus, elective Csection is an important cause of iatrogenic preterm birth. To address this problem, the American College of Obstetricians and Gynecologists (ACOG) recommends that elective birth should not be performed before 39 weeks of gestation [8,9].

In US, the occurrence of C-sections increased from 23 % in 1991 to 31.8% in 2010. In some South American countries, the frequency of Csection has reached 80%, with a direct association with the countrys per-capita income [10]. In Brazil, between 2000 and 2010, the overall C-section rate increased from 32% to 52%. In private maternity hospitals, these numbers may be alarming high and may be 80% [11].

It is paramount to identify the prevalence of morbidities and mortality in the late preterm population and create pre- and post-natal strategies for better assistance.

The aim of this study was to describe morbidities in large population of late preterm and term infants admitted to NICUs of hospitals with a high C-section rate.

Methodology

We conducted a retrospective, descriptive cross-sectional study, of patients born in 3 private maternity hospitals (two in Rio de Janeiro and one in So Paulo,Brazil) between September 2011 to February 2012. The 3 NICUs have similar infrastructure, standardized clinical practices, and clinical protocols with the same level of compliance.

All infants with gestational age between 34 and 41 weeks, admitted to the NICU were included in this study. Infants with congenital malformations were excluded.

We conducted a review of medical charts and extracted information from medical and laboratory notes.

The variables included in the study were: gestational age (weeks), type of birth, twin pregnancy, birth weight (in grams), and Apgar score 1st and 5th minutes after birth. The following clinical morbidities were analysed: Respiratory distress syndrome (RDS), need and type of ventilatory support, total time of oxygen use (hours), neonatal jaundice, jaundice requiring phototherapy, hypoglycaemia, need for intravenous fluids, hypothermia, sucking difficulties, seizures, sepsis, length of stay (days), and complications such as pneumothorax and pulmonary hypertension. Asphyxia was defined as an Apgar score of <7 at 5 minutes and/or clinical symptoms.

T test, Mann-Whitney test, and Persons Qui-Square and risk estimate were used for statistical analysis. Analysis was carried out using SPSS software, version 20.0.

The project was approved by the Committee of Ethics in Research on Human Beings (process number CAEE 0062.1.008.000-1).

Results

There were 10,854 births during the study period, and the C-section rate was 94%. From this population, 1,025 (9.5%) late preterm and 9,829 (90.5%) term new borns were included. Of these, a total of 1131 infants were admitted to the NICU, among which 485 (47.3 %) were late preterm infants and 646 (6.57%) were full term infants. We excluded 32 infants with congenital malformations from the study.

Table 1 shows the demographics of the study population. We observed statistically significant differences in the following variables: twin pregnancy, birth weight, Apgar score, and birth weight classification.

The length of stay was longer 9.86 (±7.9) for late preterm infants than for term infants 4.87(±5.8) (Table 1).

Table 2 compares the neonatal variables in the two groups.

Late preterm infants had higher rates of respiratory distress and a greater need of ventilatory support. We observed no differences in time of mechanical ventilation between the groups; however, late preterm infants required a longer duration of noninvasive respiratory support (low flow or CPAP) (Table 3).

The prevalence of neonatal jaundice was not different between groups, but a higher percentage of late preterm cases required phototherapy. In the late preterm group, we observed an increased need for intravenous fluids and a higher rate of sucking difficulties (Table 2).

Two late preterm infants experienced early sepsis and 5 experienced late sepsis; thus, 7 cases in all. There were no differences in the frequency of septic shock, seizure, hypothermia and hypoglycaemia between groups.

Figure 1 shows a plot with the most important variables stratified by gestational age. We observed that the frequency of neonatal morbidities decreases with each additional week of GA.

Neonatal morbidities were not dependent on the type of delivery, both in late preterm and term infants, and no deaths were observed in the study group.

Discussion

In recent years, the increase in the number of preterm births has been attributed to an increase in the number of late preterm infants. These findings have been described in the US, the European Union, and many other countries, and have been clearly related to induction of labor, elective caesarean section, advanced maternal age in the first pregnancy, assisted reproduction techniques and multiple pregnancies [12,13]. Gyamfi-Bannerman et al. reported that 32% late preterm childbirths were iatrogenic and 56.7% did not have any evidenced based reason for the C-section [14]. Laughon et al also observed that a considerable number of preterm infants were born by C-section delivery of unknown indication [15]. Reddy et al. described that maternal causes, obstetrical complications, major congenital anomalies, spontaneous isolated deliveries, and deliveries without medical indication, are responsible for 23% of preterm births.

In our study, we found a high C-section rate for births of both late preterm as well as term infants. In Brazil, there is a real epidemic of Csection associated with extremely high rates of late preterm births, some of which occur without any apparent medical reason. As this was a retrospective study, we could not address the indication of a Csection. The percentage of evidence-based medical indication for preterm births or iatrogenic preterm births is unknown. Further, the rate of increase in premature births can be attributed to inadequate intervention [16].

In our study, a late preterm birth rate of 9.5% was similar to that found by McIntire et al. at 9% [17]. In Brazil, Santos et al. described a late preterm birth rate of 10.8% [18], whereas in China, Xiaolu et al. reported it to be 6.2% [19]. Late preterm births are associated with higher short- and long-term morbidity rates compared to term infants [20,21]. Carrie et al. noted that the risk of morbidities was seven times greater in late preterm infants than in term infants. This risk decreased at higher gestational age, that is, at 51.7% at 34 weeks to 25.6% at 35 weeks and 12.1% at 36 weeks. We found similar data in our study. The rate of major morbidities decreased as the gestational age increased (Figure 1).

The rate of NICU admission in our study was 47.3% for late preterm infants and 6.6% for term infants. In a retrospective study that included 34,018 infants over 16 years, Gausch et al. noted that the rate of NICU admission was 61% and 5.2% in preterm and term infants, respectively. Another retrospective study, involving 233,884 births between 2002 and 2008 in 12 institutions in US, noted 35.5% vs 7.2% NICU admission rates for late preterm and term infants, respectively [22].

The most frequent clinical morbidities described in our study were RDS, neonatal jaundice requiring phototherapy, and intravenous fluids, which has already been described in previous studies.

We found a higher incidence of RDS (61%) compared to similar studies. Xiaolu et al. conducted a study in 11 tertiary hospitals in China for 12 months, with a total of 44,362 births, and observed a 42.1% incidence of RDS. Wang et al. analysed a database of tertiary hospital in Massachusetts, over seven years, and reported a 29% RDS rate in late preterm infants. Escobar et al. in a 2-year multicenter retrospective study also observed an increased risk of RDS in the late preterm group [23].

The rate of C-section births in the literature is less than that reported in our study. The high RDS rate in our study may be due to the increase in C-section delivery. Some authors have reported an association of C-section delivery with an increased risk for RDS [24].

Late preterm infants also need additional respiratory support (46.2% vs. 23.4%) and a longer duration of nasal CPAP and low flow oxygen support than term infants.

The instances of sucking difficulties and the need for intravenous fluids were also different between the two groups, which is similar to data in published studies. These factors cause gastric and intestinal motor immaturity that promotes food intolerance, compromising diet progression and prolonging hospitalization. The issue of coordinating sucking/swallowing/breathing also hampers breastfeeding and can compromise nutrition and growth of preterm infants, resulting in excessive weight loss and dehydration in the early days of life, if the patient does not receive assistance [6,8].

The incidence of jaundice requiring phototherapy differed between the two groups. In preterm infants, hyperbilirubinemia was more prevalent (risk 2-5 times higher), pronounced (risk 8 times higher to achieve values >20 mg/dl), and had prolonged evolution (peak between 5-7 days), requiring a longer hospitalization stay [25].

The rates of asphyxia, defined as an Apgar of <7 at 5 minutes with the presence of clinical changes, were very low in our study, both in term and late preterm infants, which is different from data in previously published studies. Arajo et al. in a cross-sectional study involving 239 term and 698 preterm infants observed differences in the rates of asphyxia among groups (4.2-1.6%) [3]. In a systematic review conducted by Teune et al. involving 29.37.675 infants, the rate of asphyxia was 2.7% in late preterm infants versus 0.9% in term infants [26].

A possible explanation for this could be the delivery type. Even in pregnancies with an unknown risk during prenatal care, complications can occur during labor, such as dystocia, uterine akinesia, and umbilical cord pathologies that could lead to fetal distress [27]. In our study, 945 of our deliveries were via C-section, mainly without prior labor, which probably could prevent labor complications.

We found no differences in the incidence of hypoglycemia, hypothermia, neonatal sepsis, pulmonary hypertension and pneumothorax among the groups. Feria et al. in a retrospective study also did not report differences in the incidence of hypoglycemia among the groups [28]. Ma et al. described a higher incidence of neonatal sepsis in term infants [20].

In accordance with Feria et al. study [28], we did not observe any deaths in our study. Tomashek et al. showed that early neonatal mortality is six times more frequent, late neonatal mortality is two times more frequent, and postnatal is three times more frequent in late preterm infants than term infants [29]. Arajo et al reported 12 deaths in their study, 10 of which were associated with congenital malformations and two with sepsis. We cannot compare these results, as congenital malformations were excluded in our study.

The length of stay among late preterm and term infants was 9.8 and 4.8 days, respectively, whereas it was 7.8 vs 2.6 in Kalyoncu et al. study and 17 vs 10 days in Tsai et al. study. 30 McIntire and Leveno reported that length of stay was inversely proportional to gestational age: 6.6, 5.0, 4.3, and 3.6 day in infants with GAs of 34, 35, 36, and 39 weeks, respectively [17]. Our study was designed to evaluate morbidities and mortality rates between birth and discharge in a population predominantly born by C-section. However, we did not track readmissions or assess long-term morbidities in this population.

Another limitation of our study is that the reason for interruption of pregnancy was not registered and therefore, was not evaluated. Gyamfi-Bannermanat et al. in a retrospective cohort study involving 2,693 late pre-term newborn deliveries described that 32.3% were delivered owing to iatrogenic indication, and in 56.7% cases, the birth was not evidence-based. In this same study, the authors observed that 56% births without medical indication required admissions to the NICU compared to 32% births that required a medical indication for interruption of pregnancy [14].

Our results, along with that in the literature currently, lead us to conclude that more attention is needed to late preterm births. In our study population comprising infants predominantly born by C-section, the RDS rates were higher and asphyxia rates were less compared to data in previously published studies; nonetheless, our study confirms that the late preterm population deserves attention due to a high incidence of morbidity [30].

Late preterm birth is a growing problem and a great challenge to obstetricians and neonatologists. Many of these births can be avoided with careful obstetric management of the indication of the birth type. Late preterm infants have higher risk of morbidities in the short and long term; therefore, they should not be treated as a mature term population.

Acknowledgements

We like to thank the nursing staff of Santa Joana and Perinatal Maternity Hospitals for the cooperation during the study period.

Conflict of Interest

There is no declared conflict of interest