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Physiological vital sign reference ranges for well late preterm newborns calculated during a typical two-hour newborn period between 2 hours and 7 days of life

Authors:
  • The Royal Brisbane and Women's Hospital
  • University of the Sunshine Coast & Sunshine Coast Health Institute
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Abstract

Objectives To calculate 95% reference ranges for heart rate, respiratory rate, oxygen saturation, temperature and blood pressure for well late preterm newborns between 34+0/7 and 36+6/7 weeks of gestation during typical neonatal behaviour. Approach A single site, prospective cohort study in a major Australian quaternary hospital between February and September 2019. A total of 120 late preterm newborns had their heart rate, respiratory rate and oxygen saturation measurements recorded every two seconds for up to two hours with unconditional 95% reference ranges determined using a linear mixed model with random intercept for total standard deviation calculation including repeated measures. Temperature and blood pressure measurements were collected twice - at the start and conclusion of the data recording period, with weighted 2.5th and 97.5th percentiles calculated using the mean value. Main results A total of 364,577 heart rate, 365,208 respiratory rate, 360,494 peripheral oxygen saturation, and 240 temperature and blood pressure values were obtained. The 95% reference ranges were: heart rate 102 - 164 bpm; respiratory rate 15 - 67 rpm; oxygen saturation 94 - 100%; temperature 36.4 - 37.6°C; systolic blood pressure 51 - 86 mmHg; diastolic blood pressure 28 - 61 mmHg; mean arterial pressure 35 - 68 mmHg. Significance Seven vital sign references ranges were reported for the late preterm population during a typical newborn period (such as crying, sleeping, feeding, awake and alert, and during nappy hygiene cares); internal and external validation should be completed prior to clinical use. Cut off points for escalation of care have previously been generalised to all newborns irrespective of gestational age which may result in over-treatment or a delay in recognising subtle signs of deterioration.

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Article
All newborns are at risk of deterioration as a result of failing to make the transition to extra uterine life. Signs of deterioration can be subtle and easily missed. It has been postulated that the use of an Early Warning Tool may assist clinicians in recognising and responding to signs of deterioration earlier in neonates, thereby preventing a serious adverse event. To examine whether observations from a Standard Observation Tool, applied to three neonatal Early Warning Tools, would hypothetically trigger an escalation of care more frequently than actual escalation of care using the Standard Observation Tool. A retrospective case-control study. A maternity unit in a tertiary public hospital in Australia Neonates born in 2013 of greater than or equal to 34+0 weeks gestation, admitted directly to the maternity ward from their birthing location and whose subsequent deterioration required admission to the neonatal unit, were identified as cases from databases of the study hospital. Each case was matched with three controls, inborn during the same period and who did not experience deterioration and neonatal unit admission. Clinical and physiological data recorded on a Standard Observation Tool, from time of admission to the maternity ward, for cases and controls were charted onto each of three Early Warning Tools. The primary outcome was whether the tool ‘triggered an escalation of care’. Descriptive statistics (n, %, Mean and SD) were employed. Cases (n = 26) comprised late preterm, early term and post term neonates and matched by gestational age group with 3 controls (n = 78). Overall, the Standard Observation Tool triggered an escalation of care for 92.3% of cases compared to the Early Warning Tools; New South Wales Health 80.8%, United Kingdom Newborn Early Warning Chart 57.7% and The Australian Capital Territory Neonatal Early Warning Score 11.5%. Subgroup analysis by gestational age found differences between the tools in hypothetically triggering an escalation of care. The Standard Observation Tool triggered an escalation of care more frequently than the Early Warning Tools, which may be as a result of behavioural data captured on the Standard Observation Tool and escalated, which could not be on the Early Warning Tools. Findings demonstrate that a single tool applied to all gestational age ranges may not be effective in identifying early deterioration or may over trigger an escalation of care. Further research is required into the sensitivity and specificity of Early Warning Tools in neonatal sub-populations.
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Objective: Currently, normative means and ranges of blood pressure (BP) and pulse rates in Japanese newborns are not available. The objective of the present study was to estimate BP, pulse rate, and their distribution among Japanese newborns. Methods: Using oscillometric devices, arm or calf BP and pulse rate levels were obtained from 3148 infants born between 2007 and 2014, consecutively at Suzuki Memorial Hospital, Iwanuma, Japan. Of those, data from 2628 full-term, singleton newborns with BP measured on day 3 after birth were analyzed. Results: Arm SBP/DBP and pulse rate in the reference group (n = 2628) were 70.5 ± 7.4/44.3 ± 6.7 mmHg and 117.3 ± 16.6 bpm, respectively. The 5-95th percentiles were 58-83 mmHg for SBP, 35-57 mmHg for DBP, and 91-145 bpm for pulse rate. Similar values were obtained from calf measurements. In multiple regression analysis, birth weight and spontaneous cephalic delivery were positively and light/deep sleep was inversely associated with higher arm SBP/DBP (P ≤ 0.04), whereas sex, Apgar score, gestational age, and mother's age did not significantly affect BP levels (P ≥ 0.06). Male sex, gestational age, spontaneous cephalic delivery, and light/deep sleep were inversely associated with higher pulse rate (P ≤ 0.02). Conclusion: The present study is the first to show the distributions of Asian newborns' BP levels and pulse rate. The assessment of newborns' BP levels and pulse rate should consider birth weight, gestational age after birth, and actual condition at BP measurement.
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Background and objective: Abnormal respiratory rate (RR) is a key symptom of disease in the newborn. The aim of this study was to establish the reference range for RR during the first 24 hours of life in healthy infants born at term. Methods: Infants were included at the hospital postnatal ward when time permitted. During sleep or a defined quiet state, RR was counted at 2, 4, 8, 16, and 24 hours by placing the bell of a stethoscope in front of the nostrils and mouth for 60 seconds. Data on maternal health, pregnancies, and births were obtained from medical records and the Medical Birth Registry of Norway. Results: The study included 953 infants. Median RRs were 46 breaths/minute at 2 hours, thereafter 42 to 44 breaths/minute. The 95th percentile was 65 breaths/minute at 2 hours, thereafter 58 to 60 breaths/minute. The fifth percentile was 30 to 32 breaths/minute. Within these limits, the intraindividual variation was wide. The overall mean RR was 5.2 (95% confidence interval [CI], 4.7 to 5.7, P < .001) breaths/minute higher while awake than during sleep, 3.1 (95% CI, 1.5 to 4.8, P < .001) breaths/minute higher after heavy meconium staining of the amniotic fluid, and 1.6 (95% CI, 0.8 to 2.4, P < .001) breaths/minute higher in boys than girls. RR did not differ for infants born after vaginal versus cesarean deliveries. Conclusions: The RR percentiles established from this study allow for a scientifically based use of RR when assessing newborn infants born at term.
Article
Background: All newborns are potentially at risk of deterioration as a result of failing to make the transition to extrauterine life. Clinicians in busy maternity and neonatal settings may not identify subtle early signs of deterioration. It has been postulated that the use of early warning tools (EWTs) would better assist clinicians in identifying deterioration in the 'at-risk' newborn. Aim: The aim of this review was to examine the literature to identify the use and efficacy of EWTs in earlier identification of deterioration in neonates. Methods: Electronic searches of CINAHL, MEDLINE, Academic Health Research, The Cochrane Library and Google Scholar databases were conducted. Results: The included study compared a newly developed EWT with the standard observation tool in identifying early deterioration of neonates. Of the 19 infants who received an intervention, only nine were identified as a result of the use of the EWT. Conclusion: There is not a standardised, validated EWT for use in preterm and/or term newborns in maternity settings. There is a paucity of research on the validity and effectiveness of the use of EWTs in this population. Further robust studies are needed to determine the efficacy of EWTs for use in the neonatal population cared for in maternity settings.
Article
Premature birth is a significant cause of infant and child morbidity and mortality. In the United States, the premature birth rate, which had steadily increased during the 1990s and early 2000s, has decreased annually for 7 years and is now approximately 11.39%. Human viability, defined as gestational age at which the chance of survival is 50%, is currently approximately 23 to 24 weeks in developed countries. Infant girls, on average, have better outcomes than infant boys. A relatively uncomplicated course in the intensive care nursery for an extremely premature infant results in a discharge date close to the prenatal estimated date of confinement. Despite technological advances and efforts of child health experts during the last generation, the extremely premature infant (less than 28 weeks gestation) and extremely low birth weight infant (<1000 g) remain at high risk for death and disability with 30% to 50% mortality and, in survivors, at least 20% to 50% risk of morbidity. The introduction of continuous positive airway pressure, mechanical ventilation, and exogenous surfactant increased survival and spurred the development of neonatal intensive care in the 1970s through the early 1990s. Routine administration of antenatal steroids during premature labor improved neonatal mortality and morbidity in the late 1990s. The recognition that chronic postnatal administration of steroids to infants should be avoided may have improved outcomes in the early 2000s. Evidence from recent trials attempting to define the appropriate target for oxygen saturation in preterm infants suggests arterial oxygen saturation between 91% and 95% (compared with 85%-89%) avoids excess mortality; however, final analyses of data from these trials have not been published, so definitive recommendations are still pending. The development of neonatal neurocritical intensive care units may improve neurocognitive outcomes in this high-risk group. Long-term follow-up to detect and address developmental, learning, behavioral, and social problems is critical for children born at these early gestational ages.The striking similarities in response to extreme prematurity in the lung and brain imply that agents and techniques that benefit one organ are likely to also benefit the other. Finally, because therapy and supportive care continue to change, the outcomes of extremely low birth weight infants are ever evolving. Efforts to minimize injury, preserve growth, and identify interventions focused on antioxidant and anti-inflammatory pathways are now being evaluated. Thus, treating and preventing long-term deficits must be developed in the context of a "moving target."
Article
Abstract Objective: Neonatal systemic infection is a leading cause of morbidity and mortality both in industrialized and developing countries. The aim of this prospective study was to evaluate if vital signs had a predictive power in neonatal sepsis as an early marker Methods: The study was designed as a matched case control study. Vital signs were monitorized prior to infection in newborns who had healthcare associated blood stream infection (BSI). Maximum and minimum values of the vital signs (blood pressure, heart rate, respiratory rate, temperature) of the babies at rest were recorded from the nurse observation charts 5 days prior to clinical sepsis and compared with vital signs of healthy, age matched babies. Results: Maximum mean heart rates, respiratory rates and systolic blood pressure levels of the patients in BSI group were significantly higher than the control group in the last 3 days prior to clinical deterioration. Conclusion: Monitoring vital signs closely might be helpful in a newborn infant to define a BSI. In future, a respiratory and blood pressure predictive monitoring system such as heart rate variability index may be developed for newborn patients with sepsis.
Article
Objective: To determine oxygen saturation profile over 6 h monitoring period in healthy late-preterm and term neonates during the first 48 h of age, and to assess the impact of gestational age, birth weight and method of delivery on this profile. Study design: Prospective cohort study of measurement of SpO2 over 6 h in 20 late-preterm (35 to 36 weeks gestation) and 40 term infants within 12 to 48 h of birth was conducted. Infants with cardiorespiratory symptoms or need for cardiorespiratory support at birth were excluded. Percentage time spent at SpO2 >90% and ⩽90% was calculated by gestational age and birth weight. Result: Late-preterm infants and infants born weighing <2.5 kg spent approximately 7% of the time at SpO2 ⩽90%; this time decreased as gestational age and birth weight increased. Time at SpO2 >90% was significantly different between late-preterm and term infants (93% (5%) vs 96% (3%); P =0.002). Time at SpO2 >90% was not significantly different between males and females (95% (5%) vs 95% (4%), both n=30; P =0.72) or between vaginal births and cesarean births (95% (4%), n=32, vs 95% (4%), n=28; P =0.39). Cumulative time with SpO2 <90 was mean (s.d.) of 25 (18) in preterm vs 13 (10) min in term infants. Conclusion: Over a 6-h period healthy late-preterm and term infants spent significant time at SpO2 ⩽90%. Lower gestation and lower birth weight were associated with higher time at SpO2 ⩽90%.
Article
It is well recognised that birth before 32 weeks of gestation is associated with substantial neonatal morbidity and mortality and these risks have been extensively reported. The focus of perinatal research for many years has therefore been very preterm and extremely preterm delivery, since the likelihood and severity of adverse neonatal outcomes are highest within this group. In contrast, until recently, more mature preterm infants have been understudied and indeed, almost ignored by researchers.
Article
To compare heart rate (HR) measurements from Masimo and Nellcor pulse oximeters (POs) against HR measured via a three lead electrocardiograph (ECG) (HRECG ). We also compared peripheral oxygen saturation (SpO2 ) measurements between Nellcor and Masimo oximeters. Term infants born via elective caesarean section were studied. ECG leads were placed on the infant's chest and abdomen. Masimo and Nellcor PO sensors were randomly allocated to either foot. The monitors were placed on a trolley, and data from each monitor screen captured by a video camera. HR, SpO2 measurements and signal quality were extracted. Bland-Altman analysis was used to determine agreement between HR from the ECG and each oximeter, and between SpO2 from the oximeters. We studied 44 infants of whom 4 were resuscitated. More than 8000 pairs of observations were used for each comparison of HR and SpO2. The mean difference (±2SD) between HRECG and HRN ellcor was -0.8(±11) beats per minute (bpm); between HRECG and HRM asimo was 0.2(±9) bpm. The mean (±2SD) difference between SpO2Masimo and SpO2Nellcor was -3(±15)%. The Nellcor PO measured 20% higher than the Masimo PO at SpO2 <70%. Both oximeters accurately measure HR. There was good agreement between SpO2 measurements when SpO2 ≥70%. At lower SpO2 , agreement was poorer. This article is protected by copyright. All rights reserved.
Article
Late preterm infants are often managed in nursery rooms despite the risks associated with prematurity. The objective of this study was to determine the risks facing late preterm infants admitted to nursery rooms and to establish a management strategy. A total of 210 late preterm infants and 2648 mature infants were assessed. Infants born at 35 and 36 weeks' gestation weighing >or=2000 grams admitted to a nursery room and not requiring medical intervention at birth were of particular interest. The admission rates to the neonatal intensive care unit were evaluated according to the chart review. Infants born at 35 and 36 weeks' gestation weighing >or=2000 grams had significantly higher admission rates than term infants at birth (Cochran-Mantel-Haenszel test, P < 0.001; common risk ratio, 4.27; 95% confidence interval, 2.41-7.55) and after birth (P < 0.001; common risk ratio, 3.57; 95% confidence interval, 2.40-5.33). More than 80% of admissions from the nursery room to the neonatal intensive care unit after birth were due to apnea or hypoglycemia in neonates born at 35 and 36 weeks' gestation. The admission rates due to apnea increased with decreasing gestational age. The admission rates due to hypoglycemia with no cause other than prematurity accounted for 24.3% of admissions for those born at 35 weeks' gestation and 14.1% of admissions for those born at 36 weeks' gestation; hypoglycemia due to other causes accounted for fewer admissions. The management strategy for late preterm infants should be individualized, based on apnea and hypoglycemia. The respiratory state of late preterm infants should be monitored for at least 2 days, and they should be screened for hypoglycemia on postnatal day 0.
Article
Normal ranges based on the distribution of single samples from a large number of individuals reflect both intra and interindividual variation. If the average ratio of these two sources of variation is small, then, assuming gaussian distributions, the conventional normal range will usually include a larger than expected proportion of an individual's distribution of values. When the average ratio exceeds 1.4, the normal range will include a proportion either larger or smaller than expected, depending on whether the individual's variability is less than or greater than average intraindividual variation. Investigation of multivariate normal regions in certain cases where calculations are feasible produced similar results. With these numerical guidelines, data from recent blood chemistry studies indicate that conventional normal ranges are likely to be less sensitive than desired to significant changes in an individual's biochemical state. This analysis supports the continued development and use of cumulative (in time) systems for reporting laboratory test results for individuals.
Article
Methods for estimating unconditional and conditional reference intervals for foetal size and growth based on longitudinal observations are presented. The methods are based on simple random-effects regression models and involve transforming both the response and the covariate (timepoint). A dataset from a designed longitudinal study of foetal size is analysed in detail as a motivating example.
Article
The aim of the present study was to examine gender-related differences in heart rate of human neonates controlled for their behavior. Previous studies could not find any difference in male and female fetuses and newborns, although this gender-dependent difference clearly exists in children and adults. The heart rate of 99 newborns (47 girls and 52 boys) was measured with simultaneous video recording of their behavior. Results proved that alert newborns showed the same difference as adults: boys had a significantly lower baseline heart rate than girls. This suggests that heart rate is gender-dependent from birth onward.
Article
Medical records of 203 healthy full-term infants were reviewed to determine the range of axillary temperatures for newborn infants, factors that affect temperature and nursery management of infants with temperatures outside published normal ranges. The mean birth temperature was 36.5 degrees C (S.D. = 0.6 degrees C). Temperature was associated with birth weight (p<0.0005) and the presence of maternal fever (p<0.0001) but not with type of environment or time of birth. The mean temperature increased with age, rising 0.2 degrees C by 2-3 hours after birth (p<0.0001) and 0.3 degrees C by 15-20 hours (p<0.0001). Among a subset of 114 eligible neonates the mean temperature dropped 0.2 degrees C after bathing (p<0.0001). Although 17% of all temperatures measured were in the hypothermic (< or =36.3 degrees C) range, the only response recorded by nursery staff consisted of warming by modifying the environment, e.g., bundling. Blood cultures were drawn from 51 infants (25%), 43 because of maternal intrapartum antibiotic treatment for maternal fever or prolonged duration of ruptured amniotic membranes (>24 hours) and none for evaluation of abnormal temperatures. No infants had systemic infections and all were discharged in stable condition. Newborn axillary temperatures in our nursery were considerably lower than what has been previously described as "normal." Given the frequency of "hypothermia" and absence of associated illness, we believe the reference range for newborn temperatures should be expanded to include lower temperatures.
Article
Because of its multiple involvement in physiological processes, autonomic nervous system (ANS) activity, a key regulator of homeostatic control, demonstrates a progressive increase during pregnancy. The profile of its maturation, mainly in the parasympathetic arm, in premature or full term infants, may help us to better understand its pathophysiological role. We prospectively evaluated ANS maturity in a group of 23 premature (PREM) infants at their theoretical term age and in 8 full term (FT) newborns. All recordings were registered close to the theoretical full term period (from 38 to 41 weeks) for the PREM group and during the first week of life for the FT newborns. Polygraphic recordings, EEG monitoring associated with visual clinical control, and Holter ECG, were performed simultaneously. ANS indices were then calculated during quiet sleep periods, using Wavelet transform of RR (beat to beat) intervals. High frequency components were found to be significantly lower in the PREM than in the FT group (p<0.05). Furthermore, at theoretical full term age, the greater the prematurity, the lower was parasympathetic activity. Because it is easy, monitoring of parasympathetic activity may help us to understand autonomic maturation and its clinical prognostic implications.
Article
The metabolic rate of the fetus per tissue weight is relatively high when compared to that of an adult. Moreover, heat is transferred to the fetus via the placenta and the uterus, resulting in a 0.3 degrees C to 0.5 degrees C higher temperature than that of the mother. Therefore, fetal temperature is maternally dependent until birth. At birth, the neonate rapidly cools in response to the relatively cold extrauterine environment. Thus, the neonatal temperature rapidly drops soon after birth. In order to survive, the neonate must accelerate heat production via nonshivering thermogenesis (NST), which is coupled to lypolysis in brown adipose tissue. Heat is produced by uncoupling ATP synthesis via the oxidation of fatty acids in the mitochondria, utilizing uncoupled protein. Thermogenesis must begin shortly after birth and continue for several hours. Since thermogenesis requires adequate oxygenation, a distressed neonate with hypoxemia cannot produce an adequate amount of heat to increase its temperature. In contrast to the neonate, the fetus cannot produce extra heat production. This is because the fetus is exposed to inhibitors to NST, which are produced in the placenta and then enter the fetal circulation. The important inhibitors include adenosine and prostaglandin E2, both of which have strong anti-lypolytic actions. The inhibitors play an important role in the metabolic adaptation of a physiological hypoxic fetus because NST requires adequate oxygenation. Furthermore, the presence of NST inhibitors allows the fetus to accumulate an adequate amount of brown adipose tissue before birth. The umbilical circulation transfers 85% of the heat produced by the fetus to the maternal circulation. The remaining 15% is dissipated through the fetal skin to the amnion, and is then transferred through the uterine wall to the maternal abdomen. As long as fetal heat production and loss are appropriately balanced, the temperature differential between the fetus and the mother remains constant (heat clump). However, when the umbilical circulation is occluded for any reason, the fetal temperature will rise in relation to the extent of the occlusion. The fetal temperature may elevate to the hyperthermic range in cases of acute cord occlusion; if this occurs, fetal growth, including brain development, may be impacted. Experimentally induced cord occlusion, which is recognized as a significant cause of brain damage, results in a rapid elevation of body temperature; however, the brain temperature tends to remain constant. This is considered to be a cerebral thermoregulatory adaptation to hypoxemia, which has the physiologic advantage of protecting the fetus from hyperthermia, a condition that predisposes the fetus to hypoxic injury (cerebral hypometabolism). A number of thermoregularatory mechanisms are in place to maintain normal fetal and neonatal growth. Data has primarily been collected from animal studies; aside from the strict thermal control provided in the newborn nursery, little information exists concerning these mechanisms in the human fetus and neonate. Probably further information on thermoregulation is necessary specially to improve perinatal management for hypoxic fetuses.
Article
Because the optimal concentration of oxygen (FiO2) required for stabilization of the newly born infant has not been established, the FiO2 is commonly adjusted according to the infant's oxygen saturation (SpO2). We aimed to determine the range of pre-ductal SpO2 in the first minutes of life in healthy newborn infants. We applied an oximetry sensor to the infant's right palm or wrist of term and preterm deliveries immediately after birth. Infants who received any resuscitation or supplemental oxygen were excluded. SpO2 was recorded at 60 second intervals for at least 5 minutes and until the SpO2 was >90%. A total of 205 deliveries were monitored; 30 infants were excluded from the study. SpO2 readings were obtained within 60 seconds of age from 92 of 175 infants (53%). The median (interquartile range) SpO2 at 1 minute was 63% (53%-68%). There was a gradual rise in SpO2 with time, with a median SpO2 at 5 minutes of 90% (79%-91%). Many newborns have an SpO2 <90% during the first 5 minutes of life. This should be considered when choosing SpO2 targets for infants treated with supplemental oxygen in the delivery room.
Article
There has been a temporal trend towards increased birth weight over the past three decades. This increase in birth weight may have resulted in an increase in neonatal blood pressure. Neonatal hypertension is becoming more common, especially in neonatal intensive care unit survivors. Current normative values are required to assist in diagnosis and appropriate management of neonatal hypotension and hypertension. The objective of this study was to determine normative blood pressure readings in healthy term neonates. Term neonates from the postnatal ward were enrolled from August 2003 to August 2005. Exclusion criteria included infants of mothers with preeclampsia, hypertension of any cause, gestational diabetes, type 1 diabetes mellitus and illicit substance use, infant congenital or chromosomal anomaly, admission to the neonatal intensive care unit or possible sepsis. Of the 406 infants enrolled, 218 were male. The median systolic, diastolic and mean blood pressures on day 1 of life were 65 mmHg, 45 mmHg, and 48 mmHg, respectively. On day 4, these values had increased to 70 mmHg, 46 mmHg and 54 mmHg. There was a significant elevation in blood pressure from day 1 to day 2 of life. There was no significant difference in blood pressure readings with respect to birth weight or length. The only significant difference between the sexes was a lower mean and diastolic pressure on day 2 in boys. This study has provided current normative blood pressure readings of healthy term neonates that can be used to assess both hypotension and hypertension in the term neonate. No increase in blood pressure was noted from previous studies.
Safety and Quality Improvement Guide Standard 9: Recognising and Responding to Clinical Deterioration in Acute Health Care. Commonwealth of Australia
Care ACoSaQiH, October 2012. Safety and Quality Improvement Guide Standard 9: Recognising and Responding to Clinical Deterioration in Acute Health Care. Commonwealth of Australia, New South Wales 2012, Available from: http://www. safetyandquality.gov.au/wp-content/uploads/2012/10/Standard9_Oct_2012_WEB. pdf.
Discharge planning and follow-up care
  • R Richards
  • T Mannix
Richards, R., Mannix, T., 2018. Discharge planning and follow-up care. In: Kain, V., Mannix, T. (Eds.), Neonatal Nursing in Australia and New Zealand: Principles for Practice. 1. Elsevier, New South Wales, pp. 488-507.
Late preterm infants: morbidities, mortality, and management recommendations
  • Huff
Initial nursery care
  • Gardner