Epidemiology of SIDS and explained sudden infant deaths. CESDI SUDI Research Group

Sleep-Related Sudden Unexpected Infant Death Among Infants Prenatally Substance Exposed

BACKGROUND AND OBJECTIVES

Maternal substance use during pregnancy heightens risk of sudden unexpected infant death (SUID), including through unsafe sleep practices. Families impacted by substance use frequently experience disproportionate social drivers of poor health and family vulnerability likely contributory to fatality risk. Characteristics of sleep-related SUID among infants born prenatally substance exposed versus nonexposed were compared to identify targeted prevention opportunities.

METHODS

Using the Sudden Death in the Young Registry, we examined SUID with sleep-related death between 2015 and 2020 across infants prenatally exposed versus nonexposed. Distribution of sleep environment characteristics, social drivers of poor health, and family vulnerability factors were examined using descriptive statistics and χ2.

RESULTS

Of 2010 infants who experienced sleep-related deaths, 283 (14%) were prenatally exposed. More than half of deaths involved an adult bed (52%, n = 1045) or surface sharing with an adult (53%, n = 1074). Supervisors of prenatally exposed infants were disproportionately impaired at infant death versus nonexposed (34%, n = 97 vs 16%, n = 279). Statistically significant associations between prenatal exposure history and vulnerability factors (insurance, child welfare involvement, intimate partner violence, health care barriers) were identified (P < .05).

CONCLUSIONS

Sleep-related SUID across infants prenatally exposed versus nonexposed differ in sleep environment characteristics and contributory social vulnerability. Disproportionate sleep environment hazards (surface sharing, supervisor impairment) are identified among prenatally exposed infants that should compel targeted prevention efforts, including safe sleep messaging, discouraging surface sharing, and engaging support persons during impairment periods. Addressing social needs and family vulnerability are also paramount to increase access to health care, safe sleep education, and material resource provision.

Organ weights and length anthropometry measures at autopsy for sudden infant death syndrome cases and other infant deaths in the Chicago infant mortality study

Organ weights are a possible diagnostic or pathophysiological clue to distinguishing sudden infant death syndrome (SIDS) cases from other infant deaths but suffer from major confounding. Using autopsy data from the Chicago Infant Mortality Study, a majority African-American case-control study of deceased infants under 1 year conducted 1993-96, we assessed differences in the weights of brain, thymus, kidneys, lungs, liver, spleen, total body, and four length anthropometry measures in SIDS-diagnosed infants compared to controls. Using exact and coarsened matching, we ran Bayesian linear models with these anthropometry outcomes and repeated the analyses substituting the corresponding fitted allometrically-scaled organ weight indices to account for body size. After detailed analysis and adjustment for potential confounders, we found that matched SIDS infants were generally bigger than controls, with higher mean brain, liver, spleen, thymus, lung, and total body weights, and higher mean head and chest circumference, crown-heel, crown-rump lengths. SIDS infants also had higher mean thymus, liver, spleen, lung and total body weight indices. The association with thymus weight was proportionately greater in magnitude than any other outcome measure and independent of body size. The results of these more detailed analyses are consistent with recent findings from other studies with differing racial compositions, and substantially confirm the primary organ sites for more detailed mechanistic research into the biological dysregulation contributing to underlying pathophysiology of SIDS.

Causes of sudden unexpected death in infants with and without pre-existing conditions: a retrospective autopsy study

OBJECTIVE

We investigated sudden unexpected death in infancy (SUDI) autopsy data from 1996 to 2015 inclusive, comparing findings from infants with and without pre-existing medical conditions.

DESIGN

Large, retrospective single-centre autopsy series.

SETTING

Tertiary paediatric hospital, London, UK.

METHODS

Non-identifiable autopsy findings were extracted from an existing research database for infants older than 7 days up to and including 365 days old who died suddenly and unexpectedly (SUDI; n=1739). Cases were classified into SUDI with pre-existing condition (SUDI-PEC) (n=233) versus SUDI without PEC (SUDI non-PEC) (n=929), where PEC indicates a potentially life-limiting pre-existing medical condition. Findings were compared between groups including evaluation of type of PEC and whether the deaths were medically explained (infectious or non-infectious) or apparently unexplained.

RESULTS

Median age of death was greater in SUDI-PEC compared with SUDI non-PEC (129 days vs 67 days) with similar male to female ratio (1.4:1). A greater proportion of deaths were classified as medically explained in SUDI-PEC versus SUDI non-PEC (73% vs 30%). Of the explained SUDI, a greater proportion of deaths were non-infectious for SUDI-PEC than SUDI non-PEC (66% vs 32%). SUDI-PEC (infectious) infants were most likely to have respiratory infection (64%), with susceptible PEC, including neurological, prematurity with a PEC, and syndromes or other anomalies.

CONCLUSION

SUDI-PEC deaths occur later in infancy and are likely to have their death attributed to their PEC, even in the absence of specific positive autopsy findings. Future research should aim to further define this cohort to help inform SUDI postmortem guidelines, paediatric clinical practice to reduce infant death, and to reduce the risk of overattribution of deaths in the context of a PEC.

Inconsistency Between Pictures on Baby Diaper Packaging in Europe and Safe Infant Sleep Recommendations

OBJECTIVE

To describe the level of inconsistency between pictures on baby diaper packaging and safe infant sleep recommendations (SISRs) in Europe.

STUDY DESIGN

We attempted to identify all packaging of baby diapers sold in 11 European countries for infants weighing less than 5 kg through internet searches from July 2022 through February 2023. For each type of package, we extracted whether there was a picture depicting a baby, whether the baby was sleeping, and whether the picture of the sleeping baby was inconsistent with ≥1 of 3 SISRs: (i) nonsupine sleeping position, (ii) soft objects or loose bedding, or (iii) sharing a sleep surface with another person. Data were aggregated at the country level, and a random-effects meta-analysis of proportions was used to obtain summary estimates. The outcome was the summary estimate of the proportion of pictures that were inconsistent with SISRs.

RESULTS

We identified 631 baby diaper packaging types of which 49% (95% CI: 42-57; n = 311) displayed a picture of a sleeping baby. Among those 311 packages, 79% (95% CI 73-84) were inconsistent with ≥1 SISR, including a nonsupine sleeping position, 45% (95% CI 39-51), soft objects or loose bedding such as pillows or blankets, 51% (95% CI 46-57), and sharing a sleep surface with another person, 10% (95% CI 4-18).

CONCLUSIONS

Pictures on baby diaper packaging in Europe are often inconsistent with SISRs. The prevention of sudden unexpected death in infancy requires action from manufacturers and legislators to stop parents' exposure to misleading images that may lead to dangerous practices.

Sudden Infant Death Syndrome: Risk Factors and Newer Risk Reduction Strategies

Sudden infant death syndrome (SIDS) continues to be one of the top causes of infant death in the U.S. Despite significant public health initiatives focused on high-risk populations to enhance sleep environments and techniques. The SIDS rate has remained stable in recent years. Risk factors and newer risk reduction strategies for SIDS are the focus of this review article. We conducted a comprehensive literature search on Medline, Cochrane, Embase, and Google Scholar until July 2022. The following search strings and Medical Subject Heading (MeSH) terms were used: "SIDS," "Sudden Infant Death" and "SUID". We explored the literature on SIDS for its epidemiology, pathophysiology, the role of various etiologies and their influence, associated complications leading to SIDS, and preventive and treatment modalities. Despite a more than 50% drop-in rates since the start of the "Back to Sleep" campaign in 1994, sudden infant death syndrome (SIDS) continues to be the top cause of post-neonatal mortality in the United States, despite continued educational initiatives that support safe sleep and other risk reduction strategies. The new American Academy of Pediatrics guidelines for lowering the risk of SIDS include a lot of emphasis on sleeping habits, bedding, and environment but also include elements that are frequently ignored (i.e., prenatal care, smoking, alcohol and drug use, and childhood vaccinations). This study highlights these less-frequently discussed aspects and identifies treatments that have produced beneficial behavioral shifts that benefit newborns as well as their mothers' health and wellbeing.

Risk Factors for Suffocation and Unexplained Causes of Infant Deaths

BACKGROUND

Observational studies have improved our understanding of the risk factors for sudden infant death syndrome, but separate examination of risk for sleep-related suffocation and unexplained infant deaths has been limited. We examined the association between unsafe infant sleep practices and sudden infant deaths (sleep-related suffocation and unexplained causes including sudden infant death syndrome).

METHODS

We conducted a population-based case-control study using 2016 to 2017 Centers for Disease Control and Prevention data. Controls were liveborn infants from the Pregnancy Risk Assessment Monitoring System; cases were from the Sudden Unexpected Infant Death Case Registry. We calculated risk factor prevalence among cases and controls and crude and adjusted odds ratios.

RESULTS

We included 112 sleep-related suffocation cases with 448 age-matched controls and 300 unexplained infant death cases with 1200 age-matched controls. Adjusted odds for sleep-related suffocation ranged from 18.7 (95% confidence interval [CI]: 6.8-51.3) among infants not sharing a room with their mother or caregiver to 1.9 (95% CI: 0.9-4.1) among infants with nonsupine sleep positioning. Adjusted odds for unexplained death ranged from 7.6 (95% CI: 4.7-12.2) among infants not sharing a room with their mother or caregiver to 1.6 (95% CI: 1.1-2.4) among nonsupine positioned infants.

COCLUSIONS

We confirmed previously identified risk factors for unexplained infant death and independently estimated risk factors for sleep-related suffocation. Significance of associations for suffocation followed similar patterns but was of larger magnitude. This information can be used to improve messaging about safe infant sleep.

Sudden unexpected infant death risk profiles in the first month of life

BACKGROUND

Limited improvement in current SUID rates requires further identification of its characteristics, including age-specific risk patterns.

OBJECTIVE

Compare SUID risk factors in the first week versus the remainder in the first month of life.

DESIGN/METHODS

We compared maternal and infant data from New Jersey databases for SUID from 2000 to 2015 in infants ≥ 34 weeks GA in the two groups.

RESULTS

In the period studied, 123 died in the first 27 days, 24 before seven. Deaths in the first week had a higher percentage of mothers with post-High School education (OR 3.50, CI: 1.38-8.87) and a primary Cesarean section delivery (OR 4.0, CI: 1.39-11.49), and a smaller percentage with inadequate prenatal care (OR 0.36, CI: 0.14, 0.94). A smaller percentage of first-week deaths had mothers who smoked during pregnancy or identified as Black, non-Hispanic, but these findings did not reach significance (p < .08 and p < .09, respectively).

CONCLUSIONS

SUID in the first week and the first month of life is rare. However, despite a limited sample size, data suggest that even within the first month of life, there are differences in risk patterns for SUID based on age at death. Age-specific profiles may lead to new hypotheses regarding causality and more refined risk-reduction guidelines and warrant further study.

Indeterminacy of the Diagnosis of Sudden Infant Death Syndrome Leading to Problems with the Validity of Data

The validity of infant mortality data is essential in assessing health care quality and in the setting of preventive measures. This study explores different diagnostic procedures used to determine the cause of death across forensic settings and thus the issue of the reduced validity of data. All records from three forensic medical departments that conducted autopsies on children aged 12 months or younger (n = 204) who died during the years 2007–2016 in Moravia were included. Differences in diagnostic procedures were found to be statistically significant. Each department works with a different set of risk factors and places different emphasis on different types of examination. The most significant differences could be observed in sudden infant death syndrome and suffocation diagnosis frequency. The validity of statistical data on the causes of infant mortality is thus significantly reduced. Therefore, the possibilities of public health and social policy interventions toward preventing sudden and unexpected infant death are extraordinarily complicated by this lack of data validity.

Infant Sleep Hazards and the Risk of Sudden Unexpected Death in Infancy

OBJECTIVE

To examine the effects of infant sofa-sleeping, recent use by caregivers of alcohol, cannabis, and/or other drugs, and bed type and pillows, on the risk of sudden unexpected death in infancy (SUDI) in New Zealand.

STUDY DESIGN

A nationwide prospective case-control study was implemented between March 2012 and February 2015. Data were collected during interviews with parents/caregivers. "Hazards" were defined as infant exposure to 1 or more of sofa-sleeping and recent use by caregivers of alcohol, cannabis, and other drugs. The interaction of hazards with tobacco smoking in pregnancy and bed sharing, including for very young infants, and the difference in risk for Māori and non-Māori infants, also were assessed.

RESULTS

The study enrolled 132 cases and 258 controls. SUDI risk increased with infant sofa-sleeping (imputed aOR [IaOR] 24.22, 95% CI 1.65-356.40) and with hazards (IaOR 3.35, 95% CI 1.40-8.01). The SUDI risk from the combination of tobacco smoking in pregnancy and bed sharing (IaOR 29.0, 95% CI 10.10-83.33) increased with the addition of 1 or more hazards (IaOR 148.24, 95% CI 15.72-1398), and infants younger than 3 months appeared to be at greater risk (IaOR 450.61, 95% CI 26.84-7593.14).

CONCLUSIONS

Tobacco smoking in pregnancy and bed sharing remain the greatest SUDI risks for infants and risk increases further in the presence of sofa-sleeping or recent caregiver use of alcohol and/or cannabis and other drugs. Continued implementation of effective, appropriate programs for smoking cessation, safe sleep, and supplying safe sleep beds is required to reduce New Zealand SUDI rates and SUDI disparity among Māori.

Sudden infant death syndrome: Melatonin, serotonin, and CD34 factor as possible diagnostic markers and prophylactic targets

Sudden infant death syndrome (SIDS) is one of the primary causes of death of infants in the first year of life. According to the WHO's data, the global infant mortality rate is 0.64-2 per 1,000 live-born children. Molecular and cellular aspects of SIDS development have not been identified so far. The purpose of this paper is to verify and analyze the expression of melatonin 1 and 2 receptors, serotonin (as a melatonin precursor), and CD34 molecules (as hematopoietic and endothelial markers of cardiovascular damage) in the medulla, heart, and aorta in infants who died from SIDS. An immunohistochemical method was used to investigate samples of medulla, heart, and aorta tissues of infants 3 to 9 months of age who died from SIDS. The control group included children who died from accidents. It has been shown that the expression of melatonin receptors as well as serotonin and CD34 angiogenesis markers in tissues of the medulla, heart, and aorta of infants who died from SIDS is statistically lower as compared with their expression in the same tissues in children who died from accidents. The obtained data help to clarify in detail the role of melatonin and such signaling molecules as serotonin and CD34 in SIDS pathogenesis, which can open new prospects for devising novel methods for predictive diagnosis of development and targeted prophylaxis of SIDS.

Machine Learning Approaches to Determine Feature Importance for Predicting Infant Autopsy Outcome

INTRODUCTION

Sudden unexpected death in infancy (SUDI) represents the commonest presentation of postneonatal death. We explored whether machine learning could be used to derive data driven insights for prediction of infant autopsy outcome.

METHODS

A paediatric autopsy database containing >7,000 cases, with >300 variables, was analysed by examination stage and autopsy outcome classified as 'explained (medical cause of death identified)' or 'unexplained'. Decision tree, random forest, and gradient boosting models were iteratively trained and evaluated.

RESULTS

Data from 3,100 infant and young child (<2 years) autopsies were included. Naïve decision tree using external examination data had performance of 68% for predicting an explained death. Core data items were identified using model feature importance. The most effective model was XG Boost, with overall predictive performance of 80%, demonstrating age at death, and cardiovascular and respiratory histological findings as the most important variables associated with determining medical cause of death.

CONCLUSION

This study demonstrates feasibility of using machine-learning to evaluate component importance of complex medical procedures (paediatric autopsy) and highlights value of collecting routine clinical data according to defined standards. This approach can be applied to a range of clinical and operational healthcare scenarios.

National Variations in Recent Trends of Sudden Unexpected Infant Death Rate in Western Europe

OBJECTIVE

To study recent epidemiologic trends of sudden unexpected death in infancy (SUDI) in Western Europe.

STUDY DESIGN

Annual national statistics of death causes for 14 Western European countries from 2005 to 2015 were analyzed. SUDI cases were defined as infants younger than 1 year with the underlying cause of death classified as "sudden infant death syndrome," "unknown/unattended/unspecified cause," or "accidental threats to breathing." Poisson regression models were used to study temporal trends of SUDI rates and source of variation.

RESULTS

From 2005 to 2015, SUDI accounted for 15 617 deaths, for an SUDI rate of 34.9 per 100 000 live births. SUDI was the second most common cause of death after the neonatal period (22.2%) except in Belgium, Finland, France, and the UK, where it ranked first. The overall SUDI rate significantly decreased from 40.2 to 29.9 per 100 000, with a significant rate reduction experienced for 6 countries, no significant evolution for 7 countries, and a significant increase for Denmark. The sudden infant death syndrome/SUDI ratio was 56.7%, with a significant decrease from 64.9% to 49.7% during the study period, and ranged from 6.1% in Portugal to 97.8% in Ireland. We observed between-country variations in SUDI and sudden infant death syndrome sex ratios.

CONCLUSIONS

In studied countries, SUDI decreased during the study period but remained a major cause of infant deaths, with marked between-country variations in rates, trends, and components. Standardization is needed to allow for comparing data to improve the implementation of risk-reduction strategies.

Multidisciplinary study of sudden unexpected infant death in Liguria (Italy): a nine-year report

INTRODUCTION

We conducted a retrospective analysis of cases of sudden unexpected infant death (SUID) referred to the SIDS-ALTE Center of the Liguria Region (Italy) from 2010 to 2018. In all cases, the death scene was inspected, and a multidisciplinary post-mortem evaluation was conducted. Our aim was to analyze the epidemiological data and etiological distribution.

EVIDENCE ACQUISITION

We examined 15 cases initially classified as sudden infant death.

EVIDENCE SYNTHESIS

In all cases, the death was initially unexplained. Seven cases involved males and eight involved females. Their mean age was 67.47 days; the youngest victim was 2 days old, while the oldest was 8.5 months (253 days). In 7 cases, the post-mortem analysis showed an infection of lung. In 4 cases, the prone position of the infant during sleep was identified as a risk factor. Only in one case the cause of death remains unexplained, and it was classified as sudden infant death syndrome II according to San Diego Classification.

CONCLUSIONS

In the forensic approach to cases of SUID, it is always important to conduct a thorough multidisciplinary investigation. In order to avoid procedural errors that might compromise the post-mortem investigation, it is necessary to consider the medical and social history of both mother and child, in addition to the circumstances of the death. Moreover, a complete pediatric post-mortem examination and multidisciplinary discussion are required in order to identify potentially important causative or contributory factors.

Distinct Populations of Sudden Unexpected Infant Death Based on Age

OBJECTIVES

In most recent studies, authors combine all cases of sudden infant death syndrome, other deaths from ill-defined or unknown causes, and accidental suffocation and strangulation in bed as a single population to analyze sudden unexpected infant death (SUID). Our aim with this study is to determine if there are statistically different subcategories of SUID that are based on the age of death of an infant.

METHODS

In this retrospective, cross-sectional analysis, we analyzed the Centers for Disease Control and Prevention Birth Cohort Linked Birth/Infant Death Data Set (2003-2013: 41 125 233 births and 37 624 SUIDs). Logistic regression models were developed to identify subpopulations of SUID cases by age of death, and we subsequently analyzed the effects of a set of covariates on each group.

RESULTS

Two groups were identified: sudden unexpected early neonatal deaths (SUENDs; days 0-6) and postperinatal SUIDs (days 7-364). These groups significantly differed in the distributions of assigned International Classification of Diseases, 10th Revision code, live birth order, marital status, age of mother, birth weight, and gestational length compared to postperinatal SUIDs (days 7-364). Maternal smoking during pregnancy was not a significant risk factor for deaths that occurred in the first 48 hours.

CONCLUSIONS

SUEND should be considered as a discrete entity from postperinatal SUID in future studies. These data could help improve the epidemiological understanding of SUEND and SUID and provide clues to a mechanistic understanding underlying the causes of death.

Inconsistent classification of unexplained sudden deaths in infants and children hinders surveillance, prevention and research: recommendations from The 3rd International Congress on Sudden Infant and Child Death

This report details the proceedings and conclusions from the 3rd International Congress on Unexplained Deaths in Infants and Children, held November 26–27, 2018 at the Radcliffe Institute at Harvard University. The Congress was motivated by the increasing rejection of the diagnosis Sudden Infant Death Syndrome (SIDS) in the medical examiner community, leading to falsely depressed reported SIDS rates and undermining the validity and reliability of the diagnosis, which remains a leading cause of infant and child mortality. We describe the diagnostic shift away from SIDS and the practical issues contributing to it. The Congress was attended by major figures and opinion leaders in this area from countries significantly engaged in this problem. Four categories (International Classification of Diseases (ICD)-11 categories of MH11, MH12, MH14, PB00-PB0Z) were recommended for classification, and explicit definitions and guidance were provided for death certifiers. SIDS was reframed as unexplained sudden death in infancy or SIDS/MH11 to emphasize that either term signifies the lack of explanation following a rigorous investigation. A distinct category for children over the age of 1 was recommended (MH12). Definitions and exclusions were provided for the alternative categories of accidental asphyxia and undetermined. As recommended, unexplained sudden death in infancy or SIDS on a death certificate will code a unique, trackable entity, accurately reflecting the inability to determine a definitive explanation, while satisfying surveillance needs and reliable identification for research efforts. The conclusions will be submitted to the World Health Organization for inclusion in the upcoming ICD-11.

Sudden infant death syndrome (SIDS) and the routine otoacoustic emission infant hearing screening test: an epidemiological retrospective case-control study

OBJECTIVES

To investigate whether decreased otoacoustic emission (OAE) signal recordings in the right ear are associated with an increased risk of sudden infant death syndrome (SIDS) and to monitor any temporal changes in risk factors.

DESIGN

Retrospective case-control study.

SETTING

Telephone interviews with families recruited in England between July 2016 and October 2017 who experienced the unexpected death of a child <4 years old since 2008 and control families recruited from maternity wards in Bristol and Birmingham.

PARTICIPANTS

We recruited 91 (89%) of the 102 bereaved families who made initial contact, 64 deaths were under 1 year (sudden unexpected death in infancy) of which 60 remained unexplained (SIDS). Of the 220 control families, 194 (88%) follow-up interviews were conducted. We had analysable hearing data for 24 SIDS infants (40%) and 98 controls (51%).

RESULTS

OAE signals were marginally increased rather than decreased among SIDS infants for the right ear, especially at lower frequencies, but not significantly so. The strongest predictors of SIDS were bed-sharing in hazardous (infant sleeping next to a carer who smoked, drank alcohol or slept on a sofa) circumstances (35% vs 3% controls, p<0.0001), infants found prone (33% vs 3% controls, p<0.0001) and infants whose health in the final week was 'not good' (53% vs 9% controls, p<0.0001). The prevalence of maternal smoking during pregnancy among both SIDS mothers (20%) and controls (10%) was much lower than previous studies.

CONCLUSIONS

Hearing data were difficult to obtain; larger numbers would be needed to determine if asymmetrical differences between the right and left ear were a marker for SIDS. A national prospective registry for monitoring and a renewed campaign to a new generation of parents needs to be considered underlining the initial message to place infants on their backs for sleep and the more recent message to avoid bed-sharing in hazardous circumstances.

Aerodynamic factors affecting rebreathing in infants

The rebreathing of expire air, with high carbon dioxide and low oxygen concentrations, has long been implicated in unexplained Sudden Infant Death Syndrome (SIDS) when infants are placed to sleep in a prone (facedown) position. This study elucidates the effect of the aerodynamic parameters Reynolds number, Strouhal number, and Froude number on the percentage of expired air that is reinspired (rebreathed). A nasal module was designed that served as a simplified geometric representation of infant nostrils and placed above a hard, flat surface. Quantitative and flow visualization experiments were performed to measure rebreathing, using water as the working medium, under conditions of dynamic similarity. Different anatomic (e.g., tidal volume, nostril diameter), physiological (e.g., breathing frequency), and environmental (e.g., temperature, distance from the surface) factors were considered. Increases in Strouhal number (simultaneously faster and shallower breathing) always produced higher rebreathed percentages, because rolled-up vortices in the vicinity of the nostrils had less time to move away by self-induction. Positively and negatively buoyant flows resulted in significant rebreathing. In the latter case, consistent with a warm environment and a high percentage of rebreathed CO₂, denser gas pooled in the vicinity of the nostrils. Reynolds numbers below 200 also dramatically increased rebreathing because the expired gas pooled much closer to the nostrils. These results clearly elucidated how the prone position dramatically increases rebreathing by a number of different mechanisms. Furthermore, the results offer plausible explanations of why a high-temperature environment and low birthweight are SIDS risk factors. NEW & NOTEWORTHY A fundamentally new aerodynamics-based approach to the study of rebreathing of expired air in infants is presented. Rebreathing is implicated in unexplained Sudden Infant Death Syndrome (SIDS) when infants sleep in a prone position. This is the first time that aerodynamic parameters are systematically varied and their effects on rebreathing quantified. The study provides us with a deeper understanding of the effects of breathing frequency, tidal volume (birthweight) and environmental conditions.

Is ambient air pollution associated with onset of sudden infant death syndrome: a case-crossover study in the UK

OBJECTIVES

Air pollution has been associated with increased mortality and morbidity in several studies with indications that its effect could be more severe in children. This study examined the relationship between short-term variations in criteria air pollutants and occurrence of sudden infant death syndrome (SIDS).

DESIGN

We used a case-crossover study design which is widely applied in air pollution studies and particularly useful for estimating the risk of a rare acute outcome associated with short-term exposure.

SETTING

The study used data from the West Midlands region in the UK.

PARTICIPANTS

We obtained daily time series data on SIDS mortality (ICD-9: 798.0 or ICD-10: R95) for the period 1996-2006 with a total of 211 SIDS events.

PRIMARY OUTCOME MEASURES

Daily counts of SIDS events.

RESULTS

For an IQR increase in previous day pollutant concentration, the percentage increases (95% CI) in SIDS were 16 (6 to 27) for PM₁₀, 1 (-7 to 10) for SO₂, 5 (-4 to 14) for CO, -17 (-27 to -6) for O₃, 16 (2 to 31) for NO₂ and 2 (-3 to 8) for NO after controlling for average temperature and national holidays. PM₁₀ and NO₂ showed relatively consistent association which persisted across different lag structures and after adjusting for copollutants.

CONCLUSIONS

The results indicated ambient air pollutants, particularly PM₁₀ and NO₂, may show an association with increased SIDS mortality. Thus, future studies are recommended to understand possible mechanistic explanations on the role of air pollution on SIDS incidence and the ways in which we might reduce pollution exposure among infants.

Evolution and significance of the triple risk model in sudden infant death syndrome

Sudden infant death syndrome (SIDS) is a leading cause of death in infants, although the mechanisms leading to death remain unclear. Multiple theories have emerged over time, with one of the most influential hypotheses being the triple risk model. This model, first devised in 1972 and later revised in 1994 by Filiano and Kinney, is still widely used in assisting with conceptualising and understanding sudden death in infancy. This model has evolved over time, with each version stressing that SIDS is likely to occur when certain risk factors coincide, suggesting that the lethal mechanisms in SIDS are likely to be multifactorial. All versions of the triple risk model from 1972 to the present have emphasised the complexity of SIDS and serve as useful guides for current and future research into the enigma of sudden and unexpected death in infancy.

Infants dying suddenly and unexpectedly share demographic features with infants who die with retinal and dural bleeding: a review of neural mechanisms

The cause of death in infants who die suddenly and unexpectedly (sudden unexpected death in infancy [SUDI]) remains a diagnostic challenge. Some infants have identified diseases (explained SUDI); those without explanation are called sudden infant death syndrome (SIDS). Demographic data indicate subgroups among SUDI and SIDS cases, such as unsafe sleeping and apparent life-threatening events. Infants dying suddenly with retinal and dural bleeding are often classified as abused, but in many there is no evidence of trauma. Demographic features suggest that they may represent a further subgroup of SUDI. This review examines the neuropathological hypotheses to explain SIDS and highlights the interaction of infant oxygen-conserving reflexes with the brainstem networks considered responsible for SIDS. We consider sex- and age-specific vulnerabilities related to dural bleeding and how sensitization of the dural innervation by bleeding may influence these reflexes, potentially leading to collapse or even death after otherwise trivial insults.

Swaddling and the Risk of Sudden Infant Death Syndrome: A Meta-analysis

CONTEXT

Swaddling is a traditional practice of wrapping infants to promote calming and sleep. Although the benefits and risks of swaddling in general have been studied, the practice in relation to sudden infant death syndrome remains unclear.

OBJECTIVE

The goal of this study was to conduct an individual-level meta-analysis of sudden infant death syndrome risk for infants swaddled for sleep.

DATA SOURCES

Additional data on sleeping position and age were provided by authors of included studies.

STUDY SELECTION

Observational studies that measured swaddling for the last or reference sleep were included.

DATA EXTRACTION

Of 283 articles screened, 4 studies met the inclusion criteria.

RESULTS

There was significant heterogeneity among studies (I(2) = 65.5%; P = .03), and a random effects model was therefore used for analysis. The overall age-adjusted pooled odds ratio (OR) for swaddling in all 4 studies was 1.58 (95% confidence interval [CI], 0.97-2.58). Removing the most recent study conducted in the United Kingdom reduced the heterogeneity (I(2) = 28.2%; P = .25) and provided a pooled OR (using a fixed effects model) of 1.38 (95% CI, 1.05-1.80). Swaddling risk varied according to position placed for sleep; the risk was highest for prone sleeping (OR, 12.99 [95% CI, 4.14-40.77]), followed by side sleeping (OR, 3.16 [95% CI, 2.08-4.81]) and supine sleeping (OR, 1.93 [95% CI, 1.27-2.93]). Limited evidence suggested swaddling risk increased with infant age and was associated with a twofold risk for infants aged >6 months.

LIMITATIONS

Heterogeneity among the few studies available, imprecise definitions of swaddling, and difficulties controlling for further known risks make interpretation difficult.

CONCLUSIONS

Current advice to avoid front or side positions for sleep especially applies to infants who are swaddled. Consideration should be given to an age after which swaddling should be discouraged.

Bed sharing is more common in sudden infant death syndrome than in explained sudden unexpected deaths in infancy

Aim

Despite its declining incidence, sudden infant death syndrome (SIDS) is still an important cause of death in infancy. This study investigated the environmental circumstances associated with SIDS, by analysing data from all sudden unexpected deaths in infancy (SUDI) in Sweden from 2005 to 2011.

Methods

All Swedish infants forensically autopsied up to the age of 365 days from 2005 to 2011 were included. Medical records were obtained from the hospitals and supplementary data from the Swedish Medical Birth Register.

Results

Of the 261 infants, 136 were defined as SIDS and 125 as explained SUDI. The documentation in the medical records was poor when it came to issues such as bed sharing, sleep position, smoking, breastfeeding and pacifier use. The main findings were a significantly higher prevalence of bed sharing in SIDS than in explained deaths (odds ratio 7.77, 95% confidence interval 2.36–25.57) and that prone sleeping was still overrepresented. Bronchopneumonia, other infections and congenital anomalies were the most common causes of explained SUDI.

Conclusion

Bed sharing and prone sleeping were more common in SIDS than in explained SUDI. Sparse data in medical records were a problem, and the authors are now working with the National Board of Health and Welfare on a project to establish new routines.

Not living with both parents is associated with more health- and developmental problems in infants aged 7 to 11 months: a cross sectional study

BACKGROUND

In Western countries, many children are affected by the separation of their parents. Our main objective was to assess the possible impact of parental separation family structure on certain aspects of somatic health in low-age children.

METHODS

We conducted a cross-sectional study based on data collected in the framework of free preventive medicine consultations in the French Community of Belgium. The data was derived from assessments conducted, between 2006 and 2012, on children 7 to 11 months after birth during which information of 79701 infants was collected regarding the risk of sudden infant death, psychomotor development, and development in terms of height and weight. The main outcome measures were: episode of risk of sudden infant death, polysomnography, home monitoring, psychomotor development, and body mass index.

RESULTS

The parents of 6.6% of the infants were separated. We established multivariable models, based on the presence or absence of confounders. The adjusted ORs (95% CI) of symptoms perceived as frightening, notably at night, of a prescription for a polysomnography, of an abnormal polysomnography result, and of follow-up by home monitoring were thus respectively 1.3 (1.1-1.6), 1.1 (0.9-1.3), 1.8 (1.3-2.4), and 1.3 (1.1-1.6). The adjusted ORs (95% CI) for psychomotor delay and for a body mass index above the 97(th) percentile were respectively 1.3 (1.0-1.6) and 1.2 (1.1-1.3) in the event of separation.

CONCLUSIONS

This study confirms the possibility that not living with both parents is an independent risk factor for the somatic health and psychomotor development of infants. This observation should be verified because it would have a major impact on the actions of family doctors and other first-line healthcare providers, in particular with regard to information and targeted prevention.

The role of physiological studies and apnoea monitoring in infants

There is evidence that failure of cardio-respiratory control mechanisms plays a role in the final event of the Sudden Infant Death Syndrome (SIDS). Physiological studies during sleep in both healthy term born infants and those at increased risk for SIDS have been widely used to investigate how the major risk and protective factors for SIDS identified from epidemiological studies might alter infant physiology. Clinical polysomnography (PSG) in infants who eventually succumbed to SIDS however demonstrated abnormalities that were neither sufficiently distinctive nor predictive to support routine use of PSG for infants at risk for SIDS. PSG findings have also been shown to be not predictive of recurrence of Apparent Life Threatening Events (ALTE) and thus international guidelines state that PSG is not indicated for routine evaluation in infants with an uncomplicated ALTE, although PSG may be indicated when there is clinical evidence of a sleep related breathing disorder. A decision to undertake home apnoea monitoring should consider the potential advantages and disadvantages of monitoring for that individual, in the knowledge that there is no evidence of the efficacy of such devices in preventing SIDS.

A prospective study of sudden unexpected infant death after reported maltreatment

OBJECTIVE

To examine whether infants reported for maltreatment face a heightened risk of sudden infant death syndrome (SIDS) and other leading causes of sudden unexpected infant death (SUID).

STUDY DESIGN

Linked birth and infant death records for all children born in California between 1999 and 2006 were matched to administrative child protection data. Infants were prospectively followed from birth through death or 1 year of age. A report of maltreatment was modeled as a time-varying covariate; risk factors at birth were included as baseline covariates. Multivariable competing risk survival models were used to estimate the adjusted relative hazard of postneonatal SIDS and other SUID.

RESULTS

A previous maltreatment report emerged as a significant predictor of SIDS and other SUID. After adjusting for baseline risk factors, the rate of SIDS was more than 3 times as great among infants reported for possible maltreatment (hazard ratio: 3.22; 95% CI: 2.66, 3.89).

CONCLUSION

Infants reported to child protective services have a heightened risk of SIDS and other SUID. Targeted services and improved communication between child protective services and the pediatric health care community may enhance infant well-being and reduce risk of death.

Neighbourhood income and neonatal, postneonatal and sudden infant death syndrome (SIDS) mortality in Canada, 1991-2005

BACKGROUND

Rates of infant mortality declined in Canada in the 1990s and 2000s, but the extent to which all socio-economic levels benefitted from this progress is unknown.

OBJECTIVES

This study investigated differences and time trends in neonatal, postneonatal and sudden infant death syndrome (SIDS) mortality across neighbourhood income quintiles among live births in Canada from 1991 through 2005.

METHODS

The Canadian linked live birth and infant death file was used, excluding births from Ontario, Yukon, Northwest Territories and Nunavut. Mortality rates for neonatal, postneonatal and sudden infant death syndrome (SIDS) were calculated by neighbourhood income quintile and period (1991-1995, 1996-2000, 2001-2005). Hazard ratios (HR) for neighbourhood income quintile and period were computed, adjusting for province of residence, maternal age, parity, infant sex and multiple birth.

RESULTS

In urban areas, for the entire study period (1991-2005), the poorest neighbourhood income quintile had a higher hazard of neonatal death (adjusted HR 1.24, 95% CI 1.15-1.34), postneonatal death (adjusted HR 1.58, 95% CI 1.41-1.76) and SIDS (adjusted HR 1.83, 95% CI 1.49-2.26) compared to the richest quintile. Postneonatal and SIDS mortality rates declined by 37% and 57%, respectively, between 1991-1995 and 2001-2005 whereas no significant change was observed in neonatal mortality. The decrease in postneonatal and SIDS mortality rates occurred across all income quintiles.

CONCLUSION

This study shows that despite a decrease in infant mortality and SIDS across all neighbourhood income quintiles over time in Canada, socio-economic inequalities persist. This finding highlights the need for effective infant health promotion strategies in vulnerable populations.

Prenatal cigarette smoke exposure and postnatal respiratory responses to hypoxia and hypercapnia

Prenatal cigarette smoke (CS) exposure, in combination with hypoxia and/or hyperthermia can lead to gasping and attenuated recovery from hypoxia in 7 days old rat pups. We studied 95 unanesthetized spontaneously breathing 14 days old rat pups to investigate if the destabilizing effects of increased ambient temperature and prenatal CS exposure on respiratory control observed in 7 days old rats were still evident at day 14. This postnatal age was selected as it is beyond the analogous risk period for SIDS in human. Furthermore, we investigated if the breathing responses to hypercapnia are affected by prenatal CS exposure. Since high ambient (HA) temperature can lead to gasping and aberrant respiratory control, we recorded respiratory patterns at low (24-25°C) and high (29-30°C) ambient temperatures, and under hypoxic or hypercapnic states. No gasping was observed in 14 days old rat pups. During hypoxia, breathing frequency increased in the CS-exposed group under low and HA temperatures. Rectal temperature decreased only in the sham group in response to low ambient temperature hypoxia. At HA temperature, breathing frequency increased in both sham and CS-exposed groups during hypercapnia, however, it remained elevated during washout period only in the sham group. We demonstrate that prenatal CS exposure continues to have profound effects on respiratory and thermoregulatory responses to hypoxia and hypercapnia at day 14. The attenuated respiratory and thermoregulatory responses to acute hypoxia and hypercapnia on day 14 demonstrate a strong interaction between CS exposure, respiratory control, and thermoregulation during postnatal maturation.

Numerous cortical tubers and rhabdomyomas in a case of sudden unexpected infant death

Sudden infant death syndrome is the leading cause of death in infants between the ages of 1 month to 1 year. Sudden infant death syndrome, a diagnosis of exclusion, can only be made after other explanations for unexpected death have been ruled out. Tuberous sclerosis complex is occasionally the findings in these patients with unexpected infant death. Here, we present a case of an unexpected infant death during sleep with multiple factors that confound the cause of death. We discuss these factors and attempt to delineate their contributions to arrive at a cause and mechanism of death.

Use of instructional video to prepare parents for learning infant cardiopulmonary resuscitation

Parents of premature infants often receive infant cardiopulmonary resuscitation (CPR) training prior to discharge from the hospital, but one study showed that 27.5% of parents could not demonstrate adequate CPR skills after completing an instructor-led class. We hypothesized that parents who viewed an instructional video on infant CPR before attending the class would perform better on a standardized skills test than parents who attended the class with no preparation. Parents randomized to the intervention (video) group viewed the video within 48 hours of the CPR class. Parents in the control group attended the class with no special preparation. All parents completed the CPR skills checklist test, usually within 7 days after class and before the infant's hospital discharge. The test rated subjects' skills in the areas of assessment, ventilation, and chest compressions; each section was rated as good, fair, or fail. In this pass/fail test, students had to be rated good or fair on all three sections to pass. All 10 subjects in the video group passed the test versus only 9 of 13 in the control group, but this difference was not significant (P = 0.08). However, 8 of 10 (80%) subjects in the video group were rated as good on all three sections, versus only 3 of 13 (18.7%) in the control group, and this was a significant difference (P = 0.012). We conclude that preparation of students using an instructional video prior to infant CPR class is associated with improvement in skills performance as measured by a standardized skills test. Video preparation is relatively inexpensive, eliminates the barrier of reading ability for preparation, and can be done at the convenience of the parent.

Investigating sudden unexpected death in infancy and early childhood

Sudden unexpected death is one of the most frequent ways of dying in the first year of life after the neonatal period. It is however, much less frequent after the first birthday. Investigations into the cause of death are very important, for a significant proportion of these sudden deaths can be explained only after a thorough investigation. Of the causes identified, infection is the most frequent cause; metabolic disorders and cardiovascular diseases play a role as well, although the proportion of cases is much smaller. There is now evidence that cardiac channel gene mutations also play an important role; however, identification of these conditions relies on costly testing that is not readily or widely available. The physician's role as primary care provider is critical in ensuring that families understand the results of the investigation into their child's death. It is important that everything be done to identify the cause of death so that no such tragedy recurs in the same family.

Genetics of the sudden infant death syndrome

The sudden infant death syndrome (SIDS) is currently defined as "the sudden unexpected death of an infant less than 1 year of age with onset of the fatal episode apparently occurring during sleep, that remains unexplained after a thorough investigation". SIDS, whose etiology remains rather vague, is still the major cause of death among infants between 1 month and 1 year of age in industrialized countries with varying incidences in different populations. Herein, after touching on definitory approaches and several current hypotheses concerning SIDS etiology, we focus on the triple risk model of SIDS and discuss two large classes of genetic factors potentially contributing to or predisposing for the generation of a vulnerable infant that, when encountering an environmental trigger, may succumb to SIDS. We conclude by acknowledging that for the integration of the vast and complex genetic evidence concerning SIDS, a lot more research will be required and we briefly discuss the potential use of recently presented animal models for functional studies of SIDS pathology.

Cardiovascular control during sleep in infants: Implications for Sudden Infant Death Syndrome

In infants the cardiorespiratory system undergoes significant functional maturation after birth and these changes are sleep-state dependent. Given the immaturity of these systems it is not surprising that infants are at risk of cardiorespiratory instability, especially during sleep. A failure of cardiovascular control mechanisms in particular is believed to play a role in the final event of Sudden Infant Death Syndrome (SIDS). The "triple risk model" describes SIDS as an event that results from the intersection of three overlapping factors: (1) a vulnerable infant, (2) a critical development period in homeostatic control, and (3) an exogenous stressor. This review summarises normal development of cardiovascular control during sleep in infants and describes the association of impaired cardiovascular control with the three overlapping factors proposed to be involved in SIDS pathogenesis.

Hazardous cosleeping environments and risk factors amenable to change: case-control study of SIDS in south west England

OBJECTIVES

To investigate the factors associated with sudden infant death syndrome (SIDS) from birth to age 2 years, whether recent advice has been followed, whether any new risk factors have emerged, and the specific circumstances in which SIDS occurs while cosleeping (infant sharing the same bed or sofa with an adult or child).

DESIGN

Four year population based case-control study. Parents were interviewed shortly after the death or after the reference sleep (within 24 hours) of the two control groups.

SETTING

South west region of England (population 4.9 million, 184 800 births).

PARTICIPANTS

80 SIDS infants and two control groups weighted for age and time of reference sleep: 87 randomly selected controls and 82 controls at high risk of SIDS (young, socially deprived, multiparous mothers who smoked).

RESULTS

The median age at death (66 days) was more than three weeks less than in a study in the same region a decade earlier. Of the SIDS infants, 54% died while cosleeping compared with 20% among both control groups. Much of this excess may be explained by a significant multivariable interaction between cosleeping and recent parental use of alcohol or drugs (31% v 3% random controls) and the increased proportion of SIDS infants who had coslept on a sofa (17% v 1%). One fifth of SIDS infants used a pillow for the last sleep (21% v 3%) and one quarter were swaddled (24% v 6%). More mothers of SIDS infants than random control infants smoked during pregnancy (60% v 14%), whereas one quarter of the SIDS infants were preterm (26% v 5%) or were in fair or poor health for the last sleep (28% v 6%). All of these differences were significant in the multivariable analysis regardless of which control group was used for comparison. The significance of covering the infant's head, postnatal exposure to tobacco smoke, dummy use, and sleeping in the side position has diminished although a significant proportion of SIDS infants were still found prone (29% v 10%).

CONCLUSIONS

Many of the SIDS infants had coslept in a hazardous environment. The major influences on risk, regardless of markers for socioeconomic deprivation, are amenable to change and specific advice needs to be given, particularly on use of alcohol or drugs before cosleeping and cosleeping on a sofa.

Infant bed-sharing practices and associated risk factors among births and infant deaths in Alaska

OBJECTIVE

The Alaska Division of Public Health has stated that infants may safely share a bed for sleeping if this occurs with a nonsmoking, unimpaired caregiver on a standard, adult, non-water mattress. Because this policy is contrary to recent national recommendations that discourage any bed sharing, we examined 13 years of Alaskan infant deaths that occurred while bed sharing to assess the contribution of known risk factors.

METHODS

We examined vital records, medical records, autopsy reports, and first responder reports for 93% of Alaskan infant deaths that occurred between 1992 and 2004. We examined deaths while bed sharing for risk factors including sleeping with a non-caregiver, prone position, maternal tobacco use, impairment of a bed-sharing partner, and an unsafe sleep surface. We used Pregnancy Risk Assessment Monitoring System data to describe bed-sharing practices among all live births in Alaska during 1996-2003.

RESULTS

Thirteen percent (n=126) of deaths occurred while bed sharing; 99% of these had at least one associated risk factor, including maternal tobacco use (75%) and sleeping with an impaired person (43%). Frequent bed sharing was reported for 38% of Alaskan infants. Among these, 60% of mothers reported no risk factors; the remaining 40% reported substance use, smoking, high levels of alcohol use, or most often placing their infant prone for sleeping.

CONCLUSIONS

Almost all bed-sharing deaths occurred in association with other risk factors despite the finding that most women reporting frequent bed sharing had no risk factors; this suggests that bed sharing alone does not increase the risk of infant death.

Pediatric home apnea monitors: coding, billing, and updated prescribing information for practice management

A series of new current procedural terminology codes have been created that allow health-care providers to code and bill for pediatric home apnea monitoring in the United States. Apnea monitors have been used at home on pediatric patients at risk for sudden death for > 30 years without the benefit of evidence-based efficacy studies. Nevertheless, new apnea monitor devices with expanded capability have been developed. Recommended indications for pediatric home apnea monitors are outdated and vague. It is important for the prescribing health-care provider to understand device function, as well as the pathophysiology of cardiorespiratory events in different disease states in order to make logical decisions about which monitor to prescribe, or whether to prescribe one at all. This article will review what apnea monitors are designed to do, common misperceptions about device indications vs device capability, and updated suggestions regarding the prescription, billing, and coding of pediatric apnea monitors for pediatric practice management.

Sudden infant death syndrome: changing epidemiologic patterns in California 1989-2004

OBJECTIVE

To evaluate the changes of sudden infant death syndrome (SIDS) epidemiology in California.

STUDY DESIGN

We used 1989 to 2004 California statewide death registry data. SIDS cases were selected by "age of decedent" <1 year and "cause of death" listed as SIDS.

RESULTS

We identified 6303 cases (61% males) of SIDS. SIDS incidence rate decreased by 77%, from 1.38 per 1000 births in 1989 to 0.31 per 1000 births in 2004. No further decrease in SIDS incidence was noted from 2002 to 2004. The incidence rate was highest among blacks (2.02 per 1000 births) and lowest in Asian/Pacific Islanders (0.46 per 1000 births). The overall median age at death was 82 days, with no significant change over time. However, the peak age at death shifted from 2 months of age in 1989 to 2001 to 3 months of age in 2002 to 2004. Seasonal variation in the incidence of SIDS was attenuated. The difference in incidence rates between weekdays and weekends increased over the study period.

CONCLUSIONS

The incidence rate of SIDS declined in California from 1989 to 2001, with no further decline after 2002. Several epidemiologic changes were noted: The peak age of SIDS death shifted from 2 months to 3 months of age; seasonal variation diminished; and weekday to weekend difference became more pronounced.

Extreme and conventional cardiorespiratory events and epidemiologic risk factors for SIDS

OBJECTIVE

To test the hypotheses that there is a lack of correlation between extreme events and epidemiologic risk factors for sudden infant death syndrome (SIDS), and if conventional events are normal, their numbers should increase once a circadian decrease in breathing rate is established. In addition, the number of events should decrease with maternal smoking.

STUDY DESIGN

Three outcome variables were derived from the Collaborative Home Infant Monitoring Evaluation (CHIME) of 1082 infants: (1) at least 1 extreme event lasting > or = 30 seconds, (2) at least 1 conventional event lasting > or = 20 seconds, and (3) being part of the 50% of infants with the most events.

RESULTS

Multivariate logistic regression analyses found that extreme events were not statistically associated with any known SIDS risk factors and occurred less often during the early morning. Healthy term infants had significantly fewer of these events compared with preterm infants, subsequent siblings of infants with SIDS, and infants with an apparent life-threatening event, a finding that was not evident after 43 weeks (3 weeks postterm). Conventional events increased during the night, whereas maternal smoking was associated with a decrease in conventional events. Apneic episodes persisting for > or = 40 seconds occurred in 1.8% of the infants.

CONCLUSIONS

Extreme events are associated with immaturity and do not seem to be immediate precursors of or causally related to SIDS.

Apparent life-threatening events and sudden infant death syndrome: comparison of risk factors

OBJECTIVE

To compare the risk factors of 153 cases of apparent life-threatening event (ALTE) enrolled in the multicenter Collaborative Home Infant Monitoring Evaluation (CHIME) from 1994 to 1998 with the published risk factors for sudden infant death syndrome (SIDS).

STUDY DESIGN

Trained CHIME interviewers gathered histories of infants with ALTE who met the criteria. The following risk factors were analyzed: male predominance, gestational age, low birth weight, very low birth weight, incidence of small for gestational age (SGA), age at the event, multiparity, maternal age, and smoking. Population-based SIDS studies with >100 deaths, focusing on 1 or more pertinent risk factors and carried out during the decade in which CHIME data were collected, were chosen for comparison.

RESULTS

One of the 153 infants with ALTE in this study died during follow-up (0.6%). CHIME ALTE differed significantly from SIDS in 4 respects: fewer infants with low birth weight and SGA at birth, fewer teenage pregnancies, and a younger infant age at ALTE.

CONCLUSIONS

Although a number of risk factors for ALTE are similar to those for SIDS, the differences warrant a separate focus on ALTE beyond that on SIDS.