Maternal, infant, and environmental risk factors for sudden unexpected infant deaths: results from a large, administrative cohort

Early Newborn Metabolic Patterning and Sudden Infant Death Syndrome

Importance

Sudden infant death syndrome (SIDS) is a major cause of infant death in the US. Previous research suggests that inborn errors of metabolism may contribute to SIDS, yet the relationship between SIDS and biomarkers of metabolism remains unclear.

Objective

To evaluate and model the association between routinely measured newborn metabolic markers and SIDS in combination with established risk factors for SIDS.

Design, Setting, and Participants

This was a case-control study nested within a retrospective cohort using data from the California Office of Statewide Health Planning and Development and the California Department of Public Health. The study population included infants born in California between 2005 and 2011 with full metabolic data collected as part of routine newborn screening (NBS). SIDS cases were matched to controls at a ratio of 1:4 by gestational age and birth weight z score. Matched data were split into training (2/3) and testing (1/3) subsets. Data were analyzed from January 2005 to December 2011.

Exposures

Metabolites measured by NBS and established risk factors for SIDS.

Main Outcomes and Measures

The primary outcome was SIDS. Logistic regression was used to evaluate the association between metabolic markers combined with known risk factors and SIDS.

Results

Of 2 276 578 eligible infants, 354 SIDS (0.016%) cases (mean [SD] gestational age, 38.3 [2.3] weeks; 220 male [62.1%]) and 1416 controls (mean [SD] gestational age, 38.3 [2.3] weeks; 723 male [51.1%]) were identified. In multivariable analysis, 14 NBS metabolites were significantly associated with SIDS in a univariate analysis: 17-hydroxyprogesterone, alanine, methionine, proline, tyrosine, valine, free carnitine, acetyl-L-carnitine, malonyl carnitine, glutarylcarnitine, lauroyl-L-carnitine, dodecenoylcarnitine, 3-hydroxytetradecanoylcarnitine, and linoleoylcarnitine. The area under the receiver operating characteristic curve for a 14-marker SIDS model, which included 8 metabolites, was 0.75 (95% CI, 0.72-0.79) in the training set and was 0.70 (95% CI, 0.65-0.76) in the test set. Of 32 infants in the test set with model-predicted probability greater than 0.5, a total of 20 (62.5%) had SIDS. These infants had 14.4 times the odds (95% CI, 6.0-34.5) of having SIDS compared with those with a model-predicted probability less than 0.1.

Conclusions and Relevance

Results from this case-control study showed an association between aberrant metabolic analytes at birth and SIDS. These findings suggest that we may be able to identify infants at increased risk for SIDS soon after birth, which could inform further mechanistic research and clinical efforts focused on monitoring and prevention.

Using Social Vulnerability Indices to Predict Priority Areas for Prevention of Sudden Unexpected Infant Death in Cook County, IL: Cross-Sectional Study

Background

The incidence of sudden unexpected infant death (SUID) in the United States has persisted at roughly the same level since the mid-2000s, despite intensive prevention efforts around safe sleep. Disparities in outcomes across racial and socioeconomic lines also persist. These disparities are reflected in the spatial distribution of cases across neighborhoods. Strategies for prevention should be targeted precisely in space and time to further reduce SUID and correct disparities.

Objective

We sought to aid neighborhood-level prevention efforts by characterizing communities where SUID occurred in Cook County, IL, from 2015 to 2019 and predicting where it would occur in 2021-2025 using a semiautomated, reproducible workflow based on open-source software and data.

Methods

This cross-sectional retrospective study queried geocoded medical examiner data from 2015-2019 to identify SUID cases in Cook County, IL, and aggregated them to "communities" as the unit of analysis. We compared demographic factors in communities affected by SUID versus those unaffected using Wilcoxon rank sum statistical testing. We used social vulnerability indicators from 2014 to train a negative binomial prediction model for SUID case counts in each given community for 2015-2019. We applied indicators from 2020 to the trained model to make predictions for 2021-2025.

Results

Validation of our query of medical examiner data produced 325 finalized cases with a sensitivity of 95% (95% CI 93%-97%) and a specificity of 98% (95% CI 94%-100%). Case counts at the community level ranged from a minimum of 0 to a maximum of 17. A map of SUID case counts showed clusters of communities in the south and west regions of the county. All communities with the highest case counts were located within Chicago city limits. Communities affected by SUID exhibited lower median proportions of non-Hispanic White residents at 17% versus 60% (P<.001) and higher median proportions of non-Hispanic Black residents at 32% versus 3% (P<.001). Our predictive model showed moderate accuracy when assessed on the training data (Nagelkerke R2=70.2% and RMSE=17.49). It predicted Austin (17 cases), Englewood (14 cases), Auburn Gresham (12 cases), Chicago Lawn (12 cases), and South Shore (11 cases) would have the largest case counts between 2021 and 2025.

Conclusions

Sharp racial and socioeconomic disparities in SUID incidence persisted within Cook County from 2015 to 2019. Our predictive model and maps identify precise regions within the county for local health departments to target for intervention. Other jurisdictions can adapt our coding workflows and data sources to predict which of their own communities will be most affected by SUID.

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.

Disparities in the impact of heat wave definitions on emergency department visits during the first year of life among preterm and full-term infants in California

INTRODUCTION

Heat waves will be aggravated due to climate change, making this a critical public health threat. However, heat wave definitions to activate alert systems can be ambiguous, highlighting the need to assess a range of definitions to identify those that contribute to the most adverse health outcomes. Additionally, children are highly susceptible to the impacts of heat waves, especially infants, despite the lack of focus on this subpopulation. We aimed to assess the relationship between 30 heat wave definitions and the first all-cause emergency department (ED) visits for California infants. We also examined modification of this relationship by preterm birth status and demographic characteristics to identify possible health disparities.

METHODS

Live-born, singleton deliveries from the Study of Outcomes in Mothers and Infants born in 2014-2018 were included. Thirty heat wave definitions were assessed based on temperature metrics (minimum/maximum temperatures), thresholds (90th; 92.5th; 95th; 97.5th; 99th percentiles), and duration (1-; 2-; 3-days). A time-stratified case-crossover design assessed heat wave impacts on ED visits using infants with a warm season ED visit (May-October) within the first year of life (n = 228,250). Effect modification by preterm birth status, age, sex, race/ethnicity, education, and delivery payment type was also investigated.

RESULTS

Infants demonstrated increased risk of an ED visit with exposure to all heat definitions. The 3-day minimum temperature 99th percentile definition had the highest adjusted odds ratio (AOR: 1.14; 95% CI: 1.05-1.23) for the total population. Term infants were more affected by some heat waves than preterm infants. Effect modification was additionally identified, such as by maternal education.

DISCUSSION

This study provides insight on the heat wave definitions that lead to adverse health outcomes and the identification of the most susceptible infants to these impacts, which has implications on heat-related interventions.

Maternal Mental Health Diagnoses and Infant Emergency Department Use, Hospitalizations, and Death

BACKGROUND

The period surrounding childbirth is a uniquely vulnerable time for women and their mental health. We sought to describe the association between maternal mental health diagnoses in the year prior and after birth and infant Emergency Department (ED) utilization, hospitalization, and death.

METHODS

We studied mothers who gave singleton live birth in California (2011-2017) and their infants using linked infant birth and death certificates and maternal and infant discharge records. Maternal mental health diagnoses in the year before and after birth were identified using International Classification of Diseases (ICD) codes. We abstracted infant ED visits, hospitalizations, discharge diagnoses, deaths, and causes of death. Log-linear regression was used to compare relative risks of infant outcomes between mothers with and without mental health diagnoses, adjusting for maternal variables.

RESULTS

Of the 3,067,069 mother-infant pairs, 85,047 (2.8%) mothers had at least one mental health diagnosis in the year before and after birth. Infants of mothers with mental health diagnoses were more likely to visit the ED (aRR 1.2, CI:1.1-1.2), have three or more ED visits (aRR 1.4, CI:1.3-1.4), be hospitalized (aRR 1.1, CI:1.04-1.1), and die (aRR 1.7, CI:1.6-1.8) in the first year of life. These infants were also more likely to be diagnosed with accidental injuries, nonaccidental trauma, and non-specific descriptive diagnosis (fussiness/fatigue/brief resolved unexplained event).

CONCLUSION

This large administrative cohort study showed associations between maternal mental health diagnoses and infant acute ED visits, hospitalization, and death. This study underscores the urgent need to understand what is driving these findings and how to mitigate this risk.

Birth, cognitive and behavioral effects of intrauterine cannabis exposure in infants and children: A systematic review and meta-analysis

BACKGROUND AND AIMS

Δ9-tetrahydrocannabinol (THC), the principal psychoactive component of cannabis, has been implicated in affecting fetal neurodevelopment by readily crossing the placenta. However, little is known regarding the long-term effects of intrauterine cannabis exposure. This systematic review and meta-analysis synthesized prospective and cross-sectional human studies to measure the effects of intrauterine cannabis exposure on birth, behavioral, psychological and cognitive outcomes in infancy until early childhood.

METHODS

Reporting according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, cross-sectional and prospective studies published from database inception until June 2023, investigating developmental outcomes of infants, toddlers and young children with intrauterine cannabis exposure were considered. All articles were obtained from PubMed or PsycINFO databases.

RESULTS

The literature search resulted in 932 studies, in which 57 articles met eligibility criteria. The meta-analysis revealed that intrauterine cannabis exposure increases the risk of preterm delivery [odds ratio (OR) = 1.68, 95% confidence interval (CI) = 1.05-2.71, P = 0.03], low birth weight (OR = 2.60, CI = 1.71-3.94, P < 0.001) and requirement for neonatal intensive care unit (NICU) admission (OR = 2.51, CI = 1.46-4.31; P < 0.001). Our qualitative synthesis suggests that intrauterine cannabis exposure may be associated with poorer attention and externalizing problems in infancy and early childhood. We found no evidence for impairments in other cognitive domains or internalizing behaviors.

CONCLUSIONS

Prenatal cannabis use appears to be associated with lower birth weight, preterm birth and neonatal intensive care unit admission in newborns, but there is little evidence that prenatal cannabis exposure adversely impacts behavioral or cognitive outcomes in early childhood, with the exception of attention and externalizing problems.

Developing a National-Scale Exposure Index for Combined Environmental Hazards and Social Stressors and Applications to the Environmental Influences on Child Health Outcomes (ECHO) Cohort

Tools for assessing multiple exposures across several domains (e.g., physical, chemical, and social) are of growing importance in social and environmental epidemiology because of their value in uncovering disparities and their impact on health outcomes. Here we describe work done within the Environmental influences on Child Health Outcomes (ECHO)-wide Cohort Study to build a combined exposure index. Our index considered both environmental hazards and social stressors simultaneously with national coverage for a 10-year period. Our goal was to build this index and demonstrate its utility for assessing differences in exposure for pregnancies enrolled in the ECHO-wide Cohort Study. Our unitless combined exposure index, which collapses census-tract level data into a single relative measure of exposure ranging from 0-1 (where higher values indicate higher exposure to hazards), includes indicators for major air pollutants and air toxics, features of the built environment, traffic exposures, and social determinants of health (e.g., lower educational attainment) drawn from existing data sources. We observed temporal and geographic variations in index values, with exposures being highest among participants living in the West and Northeast regions. Pregnant people who identified as Black or Hispanic (of any race) were at higher risk of living in a "high" exposure census tract (defined as an index value above 0.5) relative to those who identified as White or non-Hispanic. Index values were also higher for pregnant people with lower educational attainment. Several recommendations follow from our work, including that environmental and social stressor datasets with higher spatial and temporal resolutions are needed to ensure index-based tools fully capture the total environmental context.

Dose-response association between maternal smoking during pregnancy and the risk of infant death: a nationwide, population-based, retrospective cohort study

Background

Association of timing and intensity of maternal smoking during pregnancy with all-cause and cause-specific infant death remains inconclusive. We aimed to examine the dose-response association of maternal smoking during each of the three trimesters of pregnancy with all-cause and cause-specific infant death.

Methods

In this nationwide, population-based, retrospective cohort study, data were extracted from the U.S. National Vital Statistics System, 2015-2019. We included mother-infant pairs after excluding twin or multiple births, newborns with gestation age <37 weeks and those with low birthweight, mothers aged <18 years or ≥50 years, mothers with pre-existing hypertension or diabetes, and those with missing values for variables of interest. Poisson regression models were used to examine the association of different intensities and doses of maternal smoking during each of the three trimesters of pregnancy with all-cause and cause-specific infant death attributed to congenital anomalies, preterm birth, other perinatal conditions, sudden unexpected infant death, and infection.

Findings

A total of 13,524,204 mother-infant pairs were included in our analyses. Maternal smoking during the entire pregnancy was associated with infant all-cause death (relative risk [RR] 1.88, 95% confidence interval [95% CI] 1.79-1.97), cause-specific death due to preterm birth (1.57, 1.25-1.98), perinatal conditions excluding preterm birth (1.35, 1.10-1.65), sudden unexpected infant death (2.56, 2.40-2.73), and infection (1.51, 1.20-1.88). The risk of infant all-cause death (RR values from 1.80 to 2.15) and cause-specific infant death by preterm birth (RR values from 1.42 to 1.74), perinatal conditions excluding preterm birth (RR values from 1.46 to 1.53), sudden unexpected infant death (RR values from 2.37 to 3.04), and infection (RR values from 1.48 to 2.69) increased with the intensity of maternal cigarette use during the entire pregnancy from 1-5 to ≥11 cigarettes. Compared with mothers who smoked during their entire pregnancy, those who smoked in the first trimester and then quit smoking in the second or third trimesters of pregnancy had a reduced risk of infant all-cause death (0.71, 0.65-0.78) and sudden unexpected infant death (0.64, 0.57-0.72).

Interpretation

There was a dose-response association of maternal cigarette use during each of the three trimesters of pregnancy with all-cause and cause-specific infant death. In addition, mothers who are smokers in the first trimester and then quit smoking in the subsequent two trimesters are at decreased risk of infant all-cause mortality and sudden unexpected infant death compared with those who smoked during the entire pregnancy. These findings suggest that there is no safe level of maternal smoking in any trimester of pregnancy and maternal smokers should stop smoking during pregnancy to improve the survival of infants.

Funding

Youth Team of Humanistic and Social Science and the Innovation Team of the "Climbing" Program of Shandong University (20820IFYT1902).