Are the risk factors for SIDS different for preterm and term infants?

Low readmission rates during neonatal homecare: Gestational age and bronchopulmonary dysplasia as key predictors

AIM

Homecare for neonates has advanced, but combative analysis of contact methods remains unexplored. The aim was to identify predictors of readmission during homecare and to compare home visit, telemedicine or outpatient visit.

METHODS

This retrospective study included infants receiving homecare from 1 January 2015 to 31 December 2022. Data were obtained from local databases from six neonatal units in Denmark. The medical records of readmitted infants were reviewed. The main outcome were causes and predictors of readmission during homecare. The secondary outcome was exclusive breastfeeding at discharge.

RESULTS

The cohort consisted of 4827 infants (boys = 54.0%). The rate of unplanned readmissions was 4.6%. A gestational age (GA) <32 weeks (p-value <0.01) or bronchopulmonary dysplasia (BPD) (p-value <0.01) were predictors of readmission. There was no difference in unplanned readmissions based on contact method (p-value = 0.46 for telemedicine, p-value = 0.11 for outpatient visit). The overall exclusive breastfeeding rate at discharge from homecare was 64.1%.

CONCLUSION

Homecare can be provided for preterm and term infants while establishing oral feeding, with caution on infants with a GA < 32 or BPD. All types of contact methods during homecare investigated can be provided equally in relation to readmission and exclusive breastfeeding.

Physiology during sleep in preterm infants: Implications for increased risk for the sudden infant death syndrome

Approximately 15 million babies are born preterm (<37 weeks of completed gestation) worldwide annually. Although neonatal and perinatal medicine have contributed to the increased survival rate of preterm newborn infants, premature infants are at increased risk of mortality in the first years of life. Infants born preterm are at four times the risk of Sudden Infant Death Syndrome (SIDS) compared to infants born at term. SIDS is believed to be multifactorial in origin. The Triple Risk hypothesis has been proposed to explain this. The model suggests that when a vulnerable infant, such as one born preterm, is at a critical but unstable developmental period in homeostatic control, death may occur if exposed to an exogenous stressor, such as being placed prone for sleep. The highest risk period is at ages 2-4 months, with 90 % of deaths occurring before 6 months. The final pathway to SIDS is widely believed to involve some combination of immature cardiorespiratory control and a failure of arousal from sleep. This review will focus on the physiological factors which increase the risk for SIDS in preterm infants and how these factors may be identified and potentially lead to effective preventative strategies.

Newborn auditory brainstem response and sudden infant death syndrome

Sudden infant death syndrome (SIDS)-the sudden and unexplained death of a seemingly healthy infant, <1 year old-may be associated with abnormalities in the brain regions that underlie breathing and arousal during sleep. While post-mortem studies suggest abnormalities in SIDS infants' brainstems, there are no studies of these infants' brainstem function before death. One way to assess the function of the brainstem is with auditory brainstem response (ABR), a routine hearing-screening method that noninvasively measures the brainstem's response to sound. We hypothesize that anomalies in newborns' ABR measures may predict SIDS. Indeed, previous studies identified abnormalities in ABR characteristics in small samples of near-miss SIDS infants hospitalized for infant apnea syndrome. However, there is a need to examine the ABRs of infants who died of SIDS. Therefore, in the current study, we propose integrating two secondary datasets to examine newborns' ABRs (N = 156,972), including those who later died of SIDS (n = ~42; .27 out of every 1000 infants), using existing archived records of neonatal ABR results from a sample of newborns born in Florida. We hypothesize that infants who die from SIDS are more likely than non-SIDS infants to have abnormal ABRs as newborns. Understanding the association between SIDS and ABR may facilitate more accurate identification of an infant's risk for SIDS at birth, enabling increased monitoring, which may facilitate interventions and improve survivorship.

Transfer Entropy Modeling of Newborn Cardiorespiratory Regulation

This study investigates the complex interplay between the cardiac and respiratory systems in 268 healthy neonates born between 35 and 40 weeks of gestation. The aim is to provide a comprehensive description of the developing cardiorespiratory information transfer mechanisms as a function of gestational age (GA). This report proposes an extension of the traditional Transfer Entropy measure (TE), which employs multiple lagged versions of the time series of the intervals between two successive R waves of the QRS signal on the electrocardiogram (RR series) and respiration time series (RESP). The method aims to quantify the instantaneous and delayed effects between the two processes within a fine-grained time scale. Firstly, lagged TE was validated on a simulated dataset. Subsequently, lagged TE was employed on newborn cardiorespiratory data. Results indicate a progressive increase in information transfer as a function of gestational age, as well as significant differences in terms of instantaneous and delayed interactions between the cardiac and the respiratory system when comparing the two TE directionalities (RR→RESP vs. RESP→RR). The proposed investigation addresses the role of the different autonomic nervous system (ANS) branches involved in the cardiorespiratory system, since the sympathetic and parasympathetic branches operate at different time scales. Our results allow to infer that the two TE directionalities are uniquely and differently modulated by both branches of the ANS. TE adds an original quantitative tool to understanding cardiorespiratory imbalance in early infancy.

T-Wave Alternans in Nonpathological Preterm Infants

BACKGROUND

Sudden infant death syndrome is more frequent in preterm infants (PTI) than term infants and may be due to cardiac repolarization instability, which may manifest as T-wave alternans (TWA) on the electrocardiogram (ECG). Therefore, the aim of the present work was to analyze TWA in nonpathological PTI and to open an issue on its physiological interpretation.

METHODS

Clinical population consisted of ten nonpathological PTI (gestational age ranging from 29 3 7 to 34 2 7  weeks; birth weight ranging from 0.84 to 2.10 kg) from whom ECG recordings were obtained ("Preterm infant cardio-respiratory signals database" by Physionet). TWA was identified through the heart-rate adapting match filter method and characterized in terms of mean amplitude values (TWAA). TWA correlation with several other clinical and ECG features, among which gestational age-birth weight ratio, RR interval, heart-rate variability, and QT interval, was also performed.

RESULTS

TWA was variable among infants (TWAA = 26 ± 11 µV). Significant correlations were found between TWAA versus birth weight (ρ = -0.72, p = .02), TWAA versus gestational age-birth weight ratio (ρ = 0.76, p = .02) and TWAA versus heart-rate variability (ρ = -0.71, p = .02).

CONCLUSIONS

Our preliminary retrospective study suggests that nonpathological PTI show TWA of few tens of µV, the interpretation of which is still an open issue but could indicate a condition of cardiac risk possibly related to the low development status of the infant. Further investigations are needed to solve this issue.

Neonatal circumcision and prematurity are associated with sudden infant death syndrome (SIDS)

BACKGROUND

Sudden infant death syndrome (SIDS) is the most common cause of postneonatal unexplained infant death. The allostatic load hypothesis posits that SIDS is the result of cumulative perinatal painful, stressful, or traumatic exposures that tax neonatal regulatory systems.

AIMS

To test the predictions of the allostatic load hypothesis we explored the relationships between SIDS and two common phenotypes, male neonatal circumcision (MNC) and prematurity.

METHODS

We collated latitudinal data from 15 countries and 40 US states sampled during 2009 and 2013. We used linear regression analyses and likelihood ratio tests to calculate the association between SIDS and the phenotypes.

RESULTS

SIDS mortality rate was significantly and positively correlated with MNC. Globally (weighted): Increase of 0.06 (95% CI: 0.01-0.1, t = 2.86, p = 0.01) per 1000 SIDS mortality per 10% increase in circumcision rate. US (weighted): Increase of 0.1 (95% CI: 0.03-0.16, t = 2.81, p = 0.01) per 1000 unexplained mortality per 10% increase in circumcision rate. US states in which Medicaid covers MNC had significantly higher MNC rates (χ̄ = 0.72 vs 0.49, p = 0.007) and male/female ratio of SIDS deaths (χ̄ = 1.48 vs 1.125, p = 0.015) than other US states. Prematurity was also significantly and positively correlated with MNC. Globally: Increase of 0.5 (weighted: 95% CI: 0.02-0.086, t = 3.37, p = 0.004) per 1000 SIDS mortality per 10% increase in the prematurity rates. US: Increase of 1.9 (weighted: 95% CI: 0.06-0.32, t = 3.13, p = 0.004) per 1000 unexplained mortalities per 10% increase in the prematurity rates. Combined, the phenotypes increased the likelihood of SIDS.

CONCLUSIONS

Epidemiological analyses are useful to generate hypotheses but cannot provide strong evidence of causality. Biological plausibility is provided by a growing body of experimental and clinical evidence linking aversive preterm and early-life SIDS events. Together with historical and anthropological evidence, our findings emphasize the necessity of cohort studies that consider these phenotypes with the aim of improving the identification of at-risk infants and reducing infant mortality.

RELEVANCE FOR PATIENTS

Preterm birth and neonatal circumcision are associated with a greater risk of SIDS, and efforts should be focused on reducing their rates.

Sudden infant death syndrome: Knowledge and practise in parents of preterm infants

BACKGROUND

Preterm infants are at higher risk of sudden infant death syndrome (SIDS) compared with term born infants and the risk is inversely proportional to the gestational age and birthweight. Parents of these infants should have adequate knowledge and practise the recommended SIDS risk reduction measures.

METHODS

A survey was conducted between December 2016 and August 2017 at Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur. Parents of preterm infants ≤36 weeks' gestation were invited to answer a self-administered questionnaire to assess their knowledge and practise regarding SIDS risk reduction.

RESULTS

Forty-nine (61.33%) of the 80 parents had heard of SIDS prior to the interview, with social media being the commonest source of information (67.3%). Only 35 (43.7%) correctly answered at least five of nine questions on knowledge of SIDS risk reduction ("good knowledge"). When compared with the group of parents who answered less than five questions correctly ("poor knowledge"), there was no significant difference in the demographic and infant characteristics between the groups. The majority (68.8%) of parents practised bed sharing with their infants, and this was significantly more common in the group of parents with poor knowledge (P = 0.01). Household smoking was also significantly more common in the group of parents with poor knowledge (P = 0.048).

CONCLUSION

Knowledge on SIDS risk reduction measures was generally poor among parents of preterm infants in this study. Cigarette smoking, bed sharing and non-supine sleep positions, which are associated with increased risk of SIDS, were common practise among the present subjects.

Sudden unexpected death in infancy: biological mechanisms

Sudden unexpected death in infancy (SUDI) covers both explained and unexplained deaths. Unexplained cases or SIDS are likely to have multiple neural mechanisms contributing to the final event. The evidence ranges from subtle physiological signs related to autonomic control, to findings at autopsy of altered neurotransmitter systems, including the serotonergic system, a network that has an extensive homeostatic role in cardio-respiratory and thermoregulatory control. Processes may be altered by the vulnerability of the infant due to age, poor motor ability, or a genetic predisposition. The fatal event may occur in response to an environmental stress. A single final physiological route to death seems unlikely. An understanding of the reasons for explained SUDI also reminds us that a thorough investigation is required after each death occurs.

Arousal from sleep pathways are affected by the prone sleeping position and preterm birth: preterm birth, prone sleeping and arousal from sleep

OBJECTIVES

Preterm infants exhibit depressed arousability from sleep when compared with term infants. As the final cortical element of the arousal process may be the most critical for survival, we hypothesized that the increased vulnerability of preterm infants to the Sudden Infant Death Syndrome (SIDS) could be explained by depressed cortical arousal (CA) responses. We evaluated the effects of preterm birth on stimulus-induced arousal processes in both the prone and supine sleeping positions.

STUDY DESIGN

10 healthy preterm infants were studied with daytime polysomnography, in both supine and prone sleeping positions, at 36 weeks gestational age, 2-4 weeks, 2-3 months and 5-6 months post-term corrected age. Sub-cortical activations and cortical arousals (CA) were expressed as proportions of total arousal responses. Preterm data were compared with data from 13 healthy term infants studied at the same corrected ages.

RESULTS

In preterm infants increased CAs were observed in the prone position at all ages studied. Compared to term infants, preterm infants had significantly fewer CAs in QS when prone at 2-3 months of age and more CAs when prone at 2-4 weeks in AS. There were no differences in either sleep state when infants slept supine.

CONCLUSIONS

Prone sleeping promoted CA responses in healthy preterm infants throughout the first six months of post-term age. We have previously suggested that in term infants enhanced CA represents a critical protection against a potentially harmful situation; we speculate that for preterm-born infants the need for this protection is greater than in term infants.

Ventilatory control in infants, children, and adults with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD), or chronic lung disease of prematurity, occurs in ~30% of preterm infants (15,000 per year) and is associated with a clinical history of mechanical ventilation and/or high inspired oxygen at birth. Here, we describe changes in ventilatory control that exist in patients with BPD, including alterations in chemoreceptor function, respiratory muscle function, and suprapontine control. Because dysfunction in ventilatory control frequently revealed when O2 supply and CO2 elimination are challenged, we provide this information in the context of four important metabolic stressors: stresses: exercise, sleep, hypoxia, and lung disease, with a primary focus on studies of human infants, children, and adults. As a secondary goal, we also identify three key areas of future research and describe the benefits and challenges of longitudinal human studies using well-defined patient cohorts.

Sociodemographic and meteorological correlates of sudden infant death in Taiwan

BACKGROUND

This study was designed, using three national datasets including the Taiwan Death Registry, Taiwan Birth Registry, and National Meteorological Dataset, to examine the sociodemographic, geographic and meteorological correlates of sudden infant death syndrome (SIDS).

METHODS

One thousand, six hundred and seventy-one cases of SIDS occurring between 1994 and 2003, and 8355 matched controls were included in this nested case-control study.

RESULTS

Over the study period, the annual rate of SIDS declined only slightly, with an average annual rate of 57.9/10(5) . Male infants (adjusted odds ratio [AOR], 1.19; 95% confidence interval [CI]: 1.06-1.33), preterm births (AOR, 1.69; 95%CI: 1.33-2.13), low birthweight (AOR, 2.87; 95%CI: 2.30-3.59), and birth order ≥3 (AOR, 1.62; 95%CI: 1.37-1.92) were the demographic risk factors for SIDS. Additionally, paternal age <25 years (AOR, 1.37; 95%CI: 1.09-1.71), urbanization (AOR, 1.46; 95%CI: 1.20-1.78), lower paternal education (elementary and less; AOR, 1.28; 95%CI: 1.01-1.64), and parental age difference >10 years (AOR, 1.72; 95%CI: 1.24-2.39) were also associated with increased risk of SIDS. It was also noted that daily average temperature ranging from 9.2°C to 14.2°C (AOR, 2.10; 95%CI: 1.67-2.64) was associated with the most increased risk, while temperature ≥26.4°C (AOR 0.60, 0.61) was significantly associated with the most reduced risk.

CONCLUSION

Sociodemographic, geographic and meteorological data can be used to identify families in greater need of early guidance and to promote various prevention measures to avoid the occurrence of SIDS.

Scientific consensus forum to review the evidence underpinning the recommendations of the Australian SIDS and Kids Safe Sleeping Health Promotion Programme--October 2010

This paper summarises a 1-day scientific consensus forum that reviewed the evidence underpinning the Australian SIDS and Kids Safe Sleeping Health Promotion Programme. The focus was on each of the potentially modifiable risk factors for sudden unexpected deaths in infancy, including sudden infant death syndrome (SIDS) and fatal sleeping accidents. In particular infant sleeping position, covering of the face, exposure to cigarette smoke, room sharing, unsafe sleeping environments, bed sharing, immunisation, breastfeeding, pacifier use and Indigenous issues were discussed in depth. The participants recommended that future 'Reducing the Risk' campaign messages should focus on back to sleep, face uncovered, avoidance of cigarette smoke before and after birth, safe sleeping environment, room sharing and sleeping baby in own cot.

Interleukin-19 in fetal systemic inflammation

OBJECTIVE

The fetal inflammatory response syndrome (FIRS) is considered the fetal counterpart of the systemic inflammatory response syndrome (SIRS), which can be caused by infection and non-infection-related insults. Although the initial response is mediated by pro-inflammatory signals, the control of this response is achieved by anti-inflammatory mediators which are essential for the successful outcome of the affected individual. Interleukin (IL)-19 is capable of stimulating the production of IL-10, a major anti-inflammatory cytokine, and is a potent inducer of the T-helper 2 (Th2) response. The aim of this study was to determine if there is a change in umbilical cord plasma IL-19 and IL-10 concentrations in preterm neonates with and without acute funisitis, the histologic counterpart of FIRS.

METHODS

A case-control study was conducted including 80 preterm neonates born after spontaneous labor. Neonates were classified according to the presence (n = 40) or absence of funisitis (n = 40), which is the pathologic hallmark of FIRS. Neonates in each group were also matched for gestational age. Umbilical cord plasma IL-19 and IL-10 concentrations were determined by ELISA.

RESULTS

1) The median umbilical cord plasma IL-19 concentration was 2.5-fold higher in neonates with funisitis than in those without funisitis (median 87 pg/mL; range 20.6-412.6 pg/mL vs. median 37 pg/mL; range 0-101.7 pg/mL; p < 0.001); 2) newborns with funisitis had a significantly higher median umbilical cord plasma IL-10 concentration than those without funisitis (median 4 pg/mL; range 0-33.5 pg/mL vs. median 2 pg/mL; range 0-13.8 pg/mL; p < 0.001); and 3) the results were similar when we included only patients with funisitis who met the definition of FIRS by umbilical cord plasma IL-6 concentrations ≥ 17.5 pg/mL (p < 0.001).

CONCLUSION

IL-19 and IL-10 are parts of the immunologic response of FIRS. A subset of fetuses with FIRS had high umbilical cord plasma IL-19 concentrations. In utero exposure to high systemic concentrations of IL-19 may reprogram the immune response.

Survey of sleeping position recommendations for prematurely born infants

The risk of sudden infant death syndrome is increased in prematurely born infants compared to those born at term, particularly if they are either slept prone or on their side. The aim of this study was to determine whether a national campaign "Time to get back to sleep" had influenced the recommendations made by neonatal practitioners regarding the sleeping position for prematurely born babies prior to and after neonatal unit discharge. A questionnaire survey was sent to all UK neonatal units, of which 90% responded. The results were compared to those of a survey carried out prior to the national campaign. Analysis of the responses demonstrated that there was no significant difference in the proportion of units which recommended supine sleeping at least 1-2 weeks before discharge (78% versus 83%). Still, a minority of units provided written information for staff (26% versus 33%), but a greater proportion of units provided written information for parents (95% versus 90%, p = 0.047). All units recommended supine sleeping following discharge, and compared to the results of the previous survey, a smaller proportion of units additionally recommended side sleeping after discharge (8% versus 17%, p =0.01) and a greater proportion actively discouraged prone sleeping (62% versus 38%, p < 0.0001).

CONCLUSIONS

The majority but, importantly, not all neonatal units are giving appropriate recommendations regarding sleeping position following neonatal unit discharge. These results highlight that further education of neonatal staff regarding appropriate sleeping position for prematurely born babies remains imperative.

Hospital discharge of the high-risk neonate

This policy statement updates the guidelines on discharge of the high-risk neonate first published by the American Academy of Pediatrics in 1998. As with the earlier document, this statement is based, insofar as possible, on published, scientifically derived information. This updated statement incorporates new knowledge about risks and medical care of the high-risk neonate, the timing of discharge, and planning for care after discharge. It also refers to other American Academy of Pediatrics publications that are relevant to these issues. This statement draws on the previous classification of high-risk infants into 4 categories: (1) the preterm infant; (2) the infant with special health care needs or dependence on technology; (3) the infant at risk because of family issues; and (4) the infant with anticipated early death. The issues of deciding when discharge is appropriate, defining the specific needs for follow-up care, and the process of detailed discharge planning are addressed as they apply in general to all 4 categories; in addition, special attention is directed to the particular issues presented by the 4 individual categories. Recommendations are given to aid in deciding when discharge is appropriate and to ensure that all necessary care will be available and well coordinated after discharge. The need for individualized planning and physician judgment is emphasized.

Is bladder voiding in sleeping preterm infants accompanied by arousals?

BACKGROUND

As it has been reported that bladder voiding in sleeping full-term infants is consistently accompanied by a cortical arousal, it was the aim of the present study to find out whether this could also hold true for preterm infants.

METHODS

Polygraphic recordings were performed in 21 healthy preterm infants (10 female). The infants' gestational age at birth was 31+/-2.7 weeks and postnatal age at study entry was 26+/-8 days (mean+/-standard deviation). Bladder voiding was recorded by an adapted enuresis detector which was connected to the polygraphic computer unit. Arousals were defined as suggested by the International Paediatric Work Group on Arousals.

RESULTS

Bladder voiding was recorded 50+/-7 min after sleep onset and occurred during quiet sleep (QS) only. Heart rate (HR), respiratory frequency (RF) and electroencephalographic (EEG) frequency did not change during bladder voiding. Body movements were recorded in 52% of all preterm infants.

CONCLUSION

We found that bladder voiding was not accompanied by arousals, suggesting that the arousal process in preterm infants may be delayed due to immaturity.

Sudden infant death syndrome in twins and singletons

Twins compared with singletons and monozygous (MZ) compared with dizygous (DZ) twins are at increased risk of fetal and infant death, cerebral palsy and many congenital anomalies. The aim of this study is to investigate whether zygosity is a risk factor for the sudden infant death syndrome (SIDS). Birth registration data and draft infant death certificates for all multiple births in England and Wales 1993 to 2003 were provided by the Office for National Statistics. As a partial proxy for zygosity, same-sex was compared with opposite-sex twins for birthweight-specific mortality and mortality attributed to SIDS. Data on singleton infants were obtained by subtraction of multiple births from routinely published population births and infant deaths. SIDS mortality among low birthweight infants was significantly less in twins than singletons. The twin-singleton relative risk was reversed in infants of normal birthweight. Among infants of normal birthweight, neonatal SIDS was significantly more common in same- compared with opposite-sex pairs. Among infants of low birthweight, postneonatal SIDS was significantly more common in same- compared with opposite-sex pairs. The difference in birthweight distribution of same- compared with opposite-sex twins for neonatal SIDS suggests that zygosity is a risk factor for SIDS. As congenital cerebral anomalies are a feature of many monozygous twin conceptions, a detailed macro- and microscopical examination of the brain in twin SIDS may indicate an otherwise unrecognised pathology.

Comparison of heart rate responses during cortical and subcortical arousals in term and preterm infants

The aim of this study was to determine whether prematurity affects heart rate responses during spontaneous arousals. Polygraphic recordings were performed during undisturbed daytime naps in 35 preterm infants (gestational age at birth 32+/-2 weeks) and 35 term infants. Arousals were scored according to the recommendations of the International Paediatric Work Group on Arousals and categorized either as cortical arousals (CA) or subcortical arousals (SCA). Heart rate (HR) and respiratory frequency (RF) were measured during arousal and during the 10-s and 30-s period before and after arousal. Changes in HR and RF were expressed as the percentage of modification normalized for the 30-s period preceding arousal. Altogether, 122 arousals in preterm infants (66 CA, 56 SCA) and 105 arousals in term infants (57 CA, 48 SCA) were scored. Mean duration of the arousal period was 9+/-4 s and 8+/-3 s, respectively. In term infants, a significant increase in HR during arousal could be shown (11.3+/-8.2%; p<0.001), whereas this increase was significantly greater during CA compared to SCA (13.7+/-6.2% versus 8.4+/-9.4%; p<0.001). In contrast, HR decreased during arousal in preterm neonates (-3.9+/-19.3%; p<0.05). These findings suggest that cardiovascular control seems to be maturationally delayed in preterm infants, which may contribute to their increased risk for Sudden Infant Death Syndrome (SIDS).

Cerebral hemodynamics during arousals in preterm infants

The aim of the study was to evaluate potential changes of cerebral blood volume (CBV) related to arousals in preterm infants. As arousals are known to change different physiological parameters, it was postulated that this could also hold true for CBV. Polygraphic recordings were performed in 38 preterm infants (18 female, 20 male). The infants' gestational age at birth was 32.0+/-2.3 weeks, postconceptional age was 35.1+/-1.2 weeks and postnatal age at study entry was 24.3+/-2.9 days, birth weight was 1793+/-527 g and actual weight at study entry was 2011+/-324 g [mean (+/- standard deviation)]. CBV was measured using near infrared spectroscopy. Arousals were scored due to the guidelines of the "International Paediatric Work Group on Arousals" and categorized as either cortical (CA) or subcortical arousals (SCA). Altogether, 122 arousals (66 CA, 56 SCA) were scored. According to sleep stage, 77 arousals were analyzed in active sleep, 23 in quiet sleep and 22 in intermediate sleep. Mean duration of arousals was 8.8+/-0.3 s. CBV, cerebral vascular oxygenation and the balance between oxygen delivery and oxygen consumption remained constant during arousals in preterm infants. This was demonstrated for both CA and SCA and was independent of sleep stage, suggesting that the impact of arousals in stable preterm infants is too small to alter cerebral vascular autoregulation.