Correlation of gestational age and age at death in sudden infant death syndrome: another pointer to the role of critical developmental period?

BACKGROUND: Filiano and Kinney proposed a triple-risk model for the sudden infant death syndrome (SIDS) that involves the intersection of three risks: (1) a vulnerable infant, (2) a critical developmental period in homeostatic control, and (3) an exogenous stressor(s). The primary evidence for the role of a critical developmental period in SIDS etiology is the peak of cases around the third month of life. Independently, several studies pointed to correlation between gestational age and age at death in SIDS, but used that to assess the SIDS risk for preterm infants, ignoring further ramifications. METHODS: We did a detailed analysis of CDC data spanning over two decades (1983-2011). We focused not only on the correlation between two age variables (gestational and age at death), but also on the possibility of misdiagnosis. Also, we attempted to account for potential biases in the data induced by the ICD-9/ICD-190 transition or the "Back to Sleep" campaign. RESULTS: The peak of deaths in the third month of life, that was the main argument for the role of the critical development period, wasn't unique to SIDS. However, we confirmed an almost linear and negative correlation between gestational age and the week of death due to SIDS. This pattern (slope of correlation < 0 and significance of correlation p < 0.05) is characteristic of SIDS among all diseases analyzed in the study. CONCLUSIONS: We interpret the results as the evidence of the role of the critical development period in SIDS etiology. Possibly more attention in the future research should be put to theories that are based on homeostatic control.

Sudden Unexpected Postnatal Collapse: Review and Management.

Sudden unexpected postnatal collapse (SUPC) of healthy newborns is a catastrophic event caused by cardiorespiratory collapse in a healthy newborn. The most common cause of SUPC is poor positioning of the newborn during skin-to-skin contact or breastfeeding when the newborn is not being observed by a health professional, attentive parent, or caretaker. Maternal/newborn health care professionals need to know about the essential information, definitions, incidence, risk factors, clinical presentation, outcomes, and prevention and management strategies to minimize the occurrence and impact of SUPC. A sample SUPC hospital policy is included in the manuscript.

Sudden Infant Death Syndrome (SIDS): State of the Art and Future Directions.

Sudden infant death syndrome (SIDS) is a type of death that occurs suddenly and without any apparent explanation, affecting infants between 28 days of life and up to a year. Recognition of this entity includes performing an autopsy to determine if there is another explanation for the event and performing both an external and internal examination of the different tissues to search for possible histopathological findings. Despite the relative success of awareness campaigns and the implementation of prevention measures, SIDS still represents one of the leading causes of death among infants worldwide. In addition, although the development of different techniques has made it possible to make significant progress in the characterization of the etiopathogenic mechanisms underlying SIDS, there are still many unknowns to be resolved in this regard and the integrative consideration of this syndrome represents an enormous challenge to face both from a point of view scientific and medical view as humanitarian. For all these reasons, this paper aims to summarize the most relevant current knowledge of SIDS, exploring from the base the characterization and recognition of this condition, its forensic findings, its risk factors, and the main prevention measures to be implemented. Likewise, an attempt will be made to analyze the causes and pathological mechanisms associated with SIDS, as well as potential approaches and future paths that must be followed to reduce the impact of this condition.

Identifying infants at risk of sudden unexpected death with an automated predictive risk model.

BACKGROUND/OBJECTIVE: Sudden unexpected infant death (SUID) is a common cause of infant death. We evaluated whether a predictive risk model (PRM) - Hello Baby - which was developed to stratify children by risk of entry into foster care could also identify infants at highest risk of SUID and non-fatal unsafe sleep events. PARTICIPANTS AND SETTING: Cases: Infants with SUID or an unsafe sleep event over 5½ years in a single county. CONTROLS: All births in the same county. METHODS: Retrospective case-control study. Demographic and clinical data were collected and a Hello Baby PRM score was assigned. Descriptive statistics and the predictive value of a PRM score of 20 were calculated. RESULTS: Infants with SUID (n = 62) or an unsafe sleep event (n = 37) (cases) were compared with 23,366 births (controls). Cases and controls were similar for all demographic and clinical data except that infants with unsafe sleep events were older. Median PRM score for cases was higher than controls (17.5 vs. 10, p < 0.001); 50 % of cases had a PRM score 17-20 vs. 16 % of controls (p < 0.001). CONCLUSIONS: The Hello Baby PRM can identify newborns at high risk of SUID and non-fatal unsafe sleep events. The ability to identify high-risk newborns prior to a negative outcome allows for individualized evaluation of high-risk families for modifiable risk factors which are potentially amenable to intervention. This approach is limited by the fact that not all counties can calculate a PRM or similar score automatically.

Infant death from accidental suffocation and strangulation in bed in England and Wales: rare or unrecognised events?

BACKGROUND: Mandatory joint police and healthcare investigations of sudden unexpected death in infancy (SUDI) have been in place since 2008 in England. These include death scene examination with cause of death determined at multiprofessional case conference. Detailed evidence on sleep arrangements is available for most cases potentially leading to more being identified as due to accidental suffocation. SUDI remaining unexplained following investigation are classified as SIDS (sudden infant death syndrome) or unspecified deaths.Our objective was to determine whether detailed SUDI investigation has led to an increase in deaths classified as accidental suffocation or strangulation in bed (ASSB)? METHODS: We obtained official mortality data for England and Wales for infants dying aged 0-364 days for International Statistical Classification of Diseases and Related Health Problems, 10th revision codes R95 (SIDS), R96, R98, R99 (unspecified causes of mortality) and W75 (ASSB) for the years 2000-2019.We calculated the mortality rate for ASSB, SIDS and unspecified causes based on total live births each year. RESULTS: Unexplained SUDI decreased from 353 in 2000 to 175 in 2019, with the mortality rate falling from 0.58 to 0.29 per 1000 live births. The total postneonatal mortality rate fell during this time from 1.9 to 0.9 per 1000 live births suggesting this is a genuine fall. SIDS accounted for 70% of unexplained SUDI in 2000 falling to 49% in 2020 with a corresponding increase in R99 unspecified deaths.Few deaths were recorded as ASSB (W75), ranging between 4 in 2010 and 24 in 2001. The rate for ASSB ranged from 0.6 to 4.0 per 100000 live births. CONCLUSIONS: There is a shift away from SIDS (R95) towards unspecified causes of death (R96, R98, R99). Improved investigation of deaths has not led to increased numbers of death identified as due to ASSB. There needs to be clear guidelines on accurate classification of deaths from ASSB to facilitate learning from deaths and inform prevention efforts.

Characteristics of Sudden Unexpected Infant Deaths on Shared and Nonshared Sleep Surfaces.

OBJECTIVES: Describe characteristics of sudden unexpected infant deaths (SUID) occurring on shared or nonshared sleep surfaces. METHODS: We examined SUID among residents of 23 US jurisdictions who died during 2011 to 2020. We calculated frequencies and percentages of demographic, sleep environment, and other characteristics by sleep surface sharing status and reported differences of at least 5% between surface sharing and nonsharing infants. RESULTS: Of 7595 SUID cases, 59.5% were sleep surface sharing when they died. Compared with nonsharing infants, sharing infants were more often aged 0 to 3 months, non-Hispanic Black, publicly insured, found supine, found in an adult bed or chair/couch, had a higher number of unsafe sleep factors present, were exposed to maternal cigarette smoking prenatally, were supervised by a parent at the time of death, or had a supervisor who was impaired by drugs or alcohol at the time of death. At least 76% of all SUID had multiple unsafe sleep factors present. Among surface-sharing SUID, most were sharing with adults only (68.2%), in an adult bed (75.9%), and with 1 other person (51.6%). Surface sharing was more common among multiples than singletons. CONCLUSIONS: Among SUID, surface sharing and nonsharing infants varied by age at death, race and ethnicity, insurance type, presence of unsafe sleep factors, prenatal smoke exposure, and supervisor impairment. Most SUID, regardless of sleep location, had multiple unsafe sleep factors present, demonstrating the need for comprehensive safe sleep counseling for every family at every encounter.

A study of Samoan, Tongan, Cook Island Maori, and Niuean infant care practices in the Growing Up in New Zealand study.

BACKGROUND: Despite a low rate of infant mortality, Aotearoa New Zealand has a high rate of Sudden Unexpected Death in Infants (SUDI), with disproportionate impact for Pacific infants. This study explored the infant care practices, factors and relationships associated with increased risk of SUDI amongst Tongan, Samoan, Cook Islands Maori, and Niuean mothers in New Zealand, to inform evidence-based interventions for reducing the incidence of SUDI for Pacific families and their children. METHODS: Analysis comprised of data collected in 2009-2010 from 1089 Samoan, Tongan, Cook Islands Maori and Niuean mothers enrolled in the Growing Up in New Zealand longitudinal cohort study. The sleeping environment (bed-sharing and sleep position) of the infants was assessed at 6 weeks. Multivariable logistic regression analysis were conducted, controlling for sociodemographic factors to explore the association between selected maternal and pregnancy support and environment factors and the sleeping environment for infants. RESULTS: Mothers who converse in languages other than English at home, and mothers who consulted alternative practitioners were less likely to follow guidelines for infant sleeping position. Similarly language, smoking, alcohol, household dwelling, crowding and access to a family doctor or GP were associated with mothers following guidelines for bed-sharing. CONCLUSION: The impact of SUDI on Pacific infants may be lessened or prevented if communication about risk factors is more inclusive of diverse ethnic, cultural worldviews, and languages. Societal structural issues such as access to affordable housing is also important. This research suggests a need for more targeted or tailored interventions which promote safe sleeping and reduce rates of SUDI in a culturally respectful and meaningful way for Pasifika communities in Aotearoa, New Zealand.

Understanding the immune profile of sudden infant death syndrome - proteomic perspectives.

AIM: The aim of this study was to investigate a panel of immune proteins in cases of sudden infant death syndrome (SIDS). It was hypothesised that, in at least a subset of SIDS, a dysregulated immune response may be a contributing factor leading to death. METHODS: The subjects included 46 SIDS cases and 41 controls autopsied at the Department of Forensic Sciences, Norway. The causes of death in the controls were accidents/trauma. Samples of cerebrospinal fluid (CSF) were analysed quantitatively by Proximity Extension Assay (PEA). RESULTS: Initial results revealed that normalised protein expression differed in 35 proteins. For the purposes of this report five proteins that are involved in immune system were selected for analysis: IFNLR1 (p = 0.003), IL10 (p = 0.007), IRAK4 (p < 0.001) and IL6 (p = 0.035); all had lower protein concentrations in SIDS cases compared to controls except for CD28 (p = 0.024) which had higher protein concentrations in SIDS cases. CONCLUSION: The results confirm previous studies indicating that a dysregulation of the immune system may be a predisposing factor for SIDS. The results may indicate that these aberrant protein concentrations could lead to an inadequate response to immune triggers and uncontrolled defence mechanisms towards the common cold or other non-fatal infections.

Clinical exome sequencing elucidates underlying cause of death in sudden unexpected death of infants: two case reports.

Sudden unexpected death in infants (SUDI) is a traumatic event for families, and unfortunately its occurrence remains high in many parts of the world. Whilst cause of death is resolved for most cases, others remain undetermined following postmortem investigations. There has been a recognition of the role of genetic testing in unexplained cases, where previous studies have demonstrated the resolution of cases through DNA analyses. Here we present two case reports of SUDI cases admitted to Salt River Mortuary, South Africa, and show that underlying causes of death were determined for both infants using clinical exome sequencing. The first infant was heterozygous for a variant (rs148175795) in COL6A3, which suggested a bronchopulmonary dysplasia phenotype. This hypothesis led to finding of a second candidate variant in DMP1 (rs142880465), which may contribute towards a digenic/polygenic mechanism of a more severe phenotype. Histological analysis of retained tissue sections showed an asphyxial mechanism of death, where bronchiolar muscle weakness from an underlying bronchopulmonary dysplasia may have contributed to the asphyxia by affecting respiration. In the second infant, a homozygous variant (rs201340753) was identified in MASP1, which was heterozygous in each parent, highlighting the value of including parental DNA in genetic studies. Whilst mannose-binding lectin deficiency could not be assessed, it is plausible that this variant may have acted in combination with other risk factors within the triple-risk model to result in sudden death. These results may have genetic implications for family members, and represent possible new candidate variants for molecular autopsies.

A Systematic Approach to Evaluate Sudden Unexplained Death in Children.

OBJECTIVE: To evaluate in the Netherlands the national outcomes in providing cause of and insights into sudden and unexplained child deaths among children via the Postmortem Evaluation of Sudden Unexplained Death in Youth (PESUDY) procedure. STUDY DESIGN: Children aged 0-18 years in the Netherlands who died suddenly were included in the PESUDY procedure if their death was unexplained and their parents gave consent. The PESUDY procedure consists of pediatric and forensic examination, biochemical, and microbiological tests; radiologic imaging; autopsy; and multidisciplinary discussion. Data on history, modifiable factors, previous symptoms, performed diagnostics, and cause of death were collected between October 2016 and December 2021. RESULTS: In total, 212 cases (median age 11 months, 56% boys, 33% comorbidity) were included. Microbiological, toxicological, and metabolic testing was performed in 93%, 34%, and 32% of cases. In 95% a computed tomography scan or magnetic resonance imaging was done and in 62% an autopsy was performed. The cause of death was explained in 58% of cases and a plausible cause was identified in an additional 13%. Most children died from infectious diseases. Noninfectious cardiac causes were the second leading cause of death found. Modifiable factors were identified in 24% of non-sudden infant death syndrome/unclassified sudden infant death cases and mostly involved overlooked alarming symptoms. CONCLUSIONS: The PESUDY procedure is valuable and effective for determining the cause of death in children with sudden unexplained deaths and for providing answers to grieving parents and involved health care professionals.

Structural Bias in the Completeness of Death Investigations for Sudden Unexpected Infant Deaths (SUIDs).

OBJECTIVE: To assess sudden unexpected infant death (SUID) investigations for structural inequities by race/ethnicity and geography. METHODS: The SUID Case Registry compiles data on death investigations. We analyzed cases from 2015 to 2018 (N = 3847) to examine likelihood of an incomplete death investigation, defined as missing autopsy, missing scene investigation, or missing detailed information about where and how the body was found. We also analyzed which specific components of death investigations led to the greatest number of incomplete investigations. RESULTS: Twenty-four percent of SUIDs had incomplete death investigations. Death scenes in rural places had 1.51 times the odds of incomplete death investigations (95% confidence interval [CI], 1.19-1.92) compared with urban areas. Scene investigations led by law enforcement were more likely to result in incomplete death investigations (odds ratio [OR] = 1.49; 95% CI, 1.18-1.88) than those led by medical examiners. American Indian/Alaska Native SUIDs were more likely than other racial groups to have an incomplete investigation (OR = 1.49; 95% CI, 0.92-2.42), more likely to occur in rural places ( P = .055), and more likely to be investigated by law enforcement ( P < .001). If doll reenactments had been performed, 358 additional cases would have had complete investigations, and if SUID investigation forms had been performed, 243 additional cases would have had complete investigations. American Indian/Alaska Native SUIDs were also more likely to be missing specific components of death investigations. CONCLUSION: To produce equitable public health surveillance data used in prevention efforts, it is crucial to improve SUID investigations, especially in rural areas and among American Indian/Alaska Native babies.

Changes in background characteristics and risk factors among SIDS infants in England: cohort comparisons from 1993 to 2020.

OBJECTIVES: Using the National Child Mortality Database, this work aims to investigate background characteristics and risk factors in the sleeping environment associated with sudden infant death syndrome (SIDS) and compare the prevalence with previous English SIDS case-control studies. DESIGN: Cohort of SIDS in 2020 compared with a combined analysis of two case-control studies conducted in 1993-1996 and 2003-2006. SETTING: England, UK PARTICIPANTS: 138 SIDS deaths in 2020 compared with 402 SIDS deaths and 1387 age-equivalent surviving controls, combined from previous studies. RESULTS: The increased vulnerability of SIDS infants identified in previous studies has become more marked. The infants who died in 2020 were younger (median=66 days (IQR: 34-118) vs 86 days (IQR: 52-148), p=0.003) with an increased prevalence of low birth weight (30.5% vs 21.6%, p=0.04) and preterm births (29.6% vs 19.3%, p=0.012). The excess of socioeconomically deprived families, male infants and high levels of maternal smoking during pregnancy were still evident. Among recent deaths, fewer infants were put down or found on their side; however, there was no significant change in the proportion of infants who were put down (15.6% vs 14.6%, p=0.81) and found prone (40.4% vs 35.3%, p=0.37), despite population wide risk reduction advice over three decades. The proportional increase observed in 2003-2006 of half the deaths occurring while sleeping next to an adult was maintained in 2020, and for the vast majority (90%), this was in hazardous circumstances (adult had consumed alcohol, smoked, slept on a sofa, or the infant was premature or low birth weight and less than 3 months old). More deaths also occurred when there was a disruption in infant care routine compared with previous observations (52.6% vs 20.7%, p<0.001). CONCLUSIONS: A more targeted approach is needed with vulnerable families emphasising the importance of sleeping infants on their back and proactive planning infant sleep when there are disruptions to the normal routine, in particular to avoid hazardous co-sleeping.

Yield of Postmortem Skeletal Surveys in Infants Presenting to Emergency Care With Sudden and Unexpected Death.

OBJECTIVES: Child abuse should be considered in cases of sudden unexpected infant death (SUID). Postmortem skeletal surveys (PM-SS) are recommended to evaluate for abusive fractures in SUID. Little is known about the yield of PM-SS among infants presenting to emergency care with SUID. Our objectives were to (1) describe the presentation and care of infants with SUID at a tertiary children's hospital emergency department and (2) report PM-SS use and findings. METHODS: We performed a retrospective study of infants younger than 12 months with SUID presenting to an urban emergency department from 2007 to 2019. We describe their presentation and care, including PM-SS performance and findings, referrals to the medical examiner, and reports to child protective services (CPS). We assessed for associations between race, payer, and presentation with reports to CPS. RESULTS: Of 73 infants with SUID, concern for unsafe sleep was documented in 45 (61.6%) and 71 (97.3%) underwent cardiopulmonary resuscitation by a medical professional. All 73 (100%) underwent PM-SS and were referred to the medical examiner. Twelve definite fractures (11 rib, 1 classic metaphyseal lesion) and 8 possible fractures (7 rib, 1 classic metaphyseal lesion) were identified among 6 (8.2%) infants. Forty-three (58.9%) were reported to CPS. There were no associations between race, payer, age, or history of unsafe sleep and CPS reports. CONCLUSIONS: One in 12 cases of SUID had a possible and/or definite fracture identified on plain radiography. Multicenter studies are needed to compare yield across different postmortem imaging modalities and populations.

Current SIDS research: time to resolve conflicting research hypotheses and collaborate.

From the earliest publications on cot death or sudden infant death syndrome (SIDS) through to this day, clinical pathology and epidemiology have strongly featured infection as a constant association. Despite mounting evidence of the role of viruses and common toxigenic bacteria in the pathogenesis of SIDS, a growing school of thought featuring a paradigm based on the triple risk hypothesis that encompasses vulnerability through deranged homoeostatic control of arousal and/or cardiorespiratory function has become the mainstream view and now dominates SIDS research. The mainstream hypothesis rarely acknowledges the role of infection despite its notional potential role as a cofactor in the triple hit idea. Decades of mainstream research that has focussed on central nervous system homoeostatic mechanisms of arousal, cardiorespiratory control and abnormal neurotransmission has not been able to provide consistent answers to the SIDS enigma. This paper examines the disparity between these two schools of thought and calls for a collaborative approach. IMPACT: The popular research hypothesis explaining sudden infant death syndrome features the triple risk hypothesis with central nervous system homoeostatic mechanisms controlling arousal and cardiorespiratory function. Intense investigation has not yielded convincing results. There is a necessity to consider other plausible hypotheses (e.g., common bacterial toxin hypothesis). The review scrutinises the triple risk hypothesis and CNS control of cardiorespiratory function and arousal and reveals its flaws. Infection-based hypotheses with their strong SIDS risk factor associations are reviewed in a new context.

Qualitative assessment of infant sleep practices and other risk factors of sudden infant death syndrome (SIDS) among mothers in Lusaka, Zambia.

BACKGROUND: There is very little information on the beliefs and perceptions of mothers about SIDS and its related risk factors in Africa. To better understand parental decisions about infant sleep practices and other risk factors for SIDS, we conducted focus group discussions (FGDs) with mothers of infants in Lusaka, Zambia. METHODS: FGDs involved 35 purposively sampled mothers aged 18-49 years. FGDs were conducted using a semi-structured interview guide in the local language, Nyanja. These were translated, transcribed verbatim into English, and then coded and analyzed using thematic analysis in NVivo 12. RESULTS: Six FGDs were conducted with 35 mothers in April-May 2021 across two study sites. FGD Participants were generally aware of sudden unexplained infant deaths, with several describing stories of apparent SIDS in the community. The side sleeping position was preferred and perceived to be safer for the infant with most believing the supine position posed an aspiration or choking risk to the infant. Bedsharing was also preferred and perceived to be convenient for breastfeeding and monitoring of the infant. Experienced family members such as grandmothers and mothers-in-law, and health care workers were frequently cited as sources of information on infant sleep position. A heightened awareness of the infant's sleeping environment was suggested as a mechanism to prevent SIDS and smothering. CONCLUSIONS: Decisions about bedsharing and infant sleep position were guided by maternal beliefs and perceptions about what is convenient for breastfeeding and safer for the infant. These concerns are vital to designing tailored interventions to address sleep-related sudden infant losses in Zambia. Public health campaigns with tailored messages that address these concerns are likely to be effective at ensuring optimal uptake of safe sleep recommendations.

Racial and Ethnic Disparities in Sudden Unexpected Infant Death Among US Infants Born Preterm.

OBJECTIVE: To investigate among US infants born at <37 weeks gestation (a) racial and ethnic disparities in sudden unexpected infant death (SUID) and (b) state variation in SUID rates and non-Hispanic Black (NHB)-non-Hispanic White (NHW) SUID disparity ratio. METHODS: In this retrospective cohort analysis of linked birth and death certificates from 50 states from 2005 to 2014, SUID was defined by the following International Classification of Diseases, 9th or 10th edition, codes listed on death certificates: (7980, R95 or Recode 135; ASSB: E913, W75 or Recode 146; Unknown: 7999 R99 or Recode 134). Multivariable models were used to assess the independent association between maternal race and ethnicity and SUID, adjusting for several maternal and infant characteristics. The NHB-NHW SUID disparity ratios were calculated for each state. RESULTS: Among 4 086 504 preterm infants born during the study period, 8096 infants (0.2% or 2.0 per 1000 live births) experienced SUID. State variation in SUID ranged from the lowest rate of 0.82 per 1000 live births in Vermont to the highest rate of 3.87 per 1000 live births in Mississippi. Unadjusted SUID rates across racial and ethnic groups varied from 0.69 (Asian/Pacific Islander) to 3.51 (NHB) per 1000 live births. In the adjusted analysis, compared with NHW infants, NHB and Alaska Native/American Indian preterm infants had greater odds of SUID (aOR, 1.5;[95% CI, 1.42-1.59] and aOR, 1.44 [95% CI, 1.21-1.72]) with varying magnitude of SUID rates and NHB-NHW disparities across states. CONCLUSIONS: Significant racial and ethnic disparities in SUID among preterm infants exist with variation across US states. Additional research to identify the drivers of these disparities within and across states is needed.

Maternal infections in pregnancy and the risk of sudden unexpected infant death in the offspring in the U.S., 2011-2015.

BACKGROUND: Infection is thought to play a part in some infant deaths. Maternal infection in pregnancy has focused on chlamydia with some reports suggesting an association with sudden unexpected infant death (SUID). OBJECTIVES: We hypothesized that maternal infections in pregnancy are associated with subsequent SUID in their offspring. SETTING: All births in the United States, 2011-2015. DATA SOURCE: Centers for Disease Control and Prevention (CDC) Birth Cohort Linked Birth-Infant Death Data Files. STUDY DESIGN: Cohort study, although the data were analysed as a case control study. Cases were infants that died from SUID. Controls were randomly sampled infants that survived their first year of life; approximately 10 controls per SUID case. EXPOSURES: Chlamydia, gonorrhea and hepatitis C. RESULTS: There were 19,849,690 live births in the U.S. for the period 2011-2015. There were 37,143 infant deaths of which 17,398 were classified as SUID cases (a rate of 0.86/1000 live births). The proportion of the control mothers with chlamydia was 1.7%, gonorrhea 0.2% and hepatitis C was 0.3%. Chlamydia was present in 3.8% of mothers whose infants subsequently died of SUID compared with 1.7% of controls (unadjusted OR = 2.35, 95% CI = 2.15, 2.56; adjusted OR = 1.08, 95% CI = 0.98, 1.19). Gonorrhea was present in 0.7% of mothers of SUID cases compared with 0.2% of mothers of controls (OR = 3.09, (2.50, 3.79); aOR = 1.20(0.95, 1.49)) and hepatitis C was present in 1.3% of mothers of SUID cases compared with 0.3% of mothers of controls (OR = 4.69 (3.97, 5.52): aOR = 1.80 (1.50, 2.15)). CONCLUSIONS: The marked attenuation of SUID risk after adjustment for a wide variety of socioeconomic and demographic factors suggests the small increase in the risk of SUID of the offspring of mothers with infection with hepatitis C in pregnancy is due to residual confounding.

Sudden Unexpected Infant Deaths: 2015-2020.

OBJECTIVE: Although the US infant mortality rate reached a record low in 2020, the sudden infant death syndrome (SIDS) rate increased from 2019. To understand if the increase was related to changing death certification practices or the coronavirus disease 2019 (COVID-19) pandemic, we examined sudden unexpected infant death (SUID) rates as a group, by cause, and by race and ethnicity. METHODS: We estimated SUID rates during 2015 to 2020 using US period-linked birth and death data. SUID included SIDS, unknown cause, and accidental suffocation and strangulation in bed. We examined changes in rates from 2019 to 2020 and assessed linear trends during prepandemic (2015-2019) using weighted least squares regression. We also assessed race and ethnicity trends and quantified COVID-19-related SUID. RESULTS: Although the SIDS rate increased significantly from 2019 to 2020 (P < .001), the overall SUID rate did not (P = .24). The increased SIDS rate followed a declining linear trend in SIDS during 2015 to 2019 (P < .001). Other SUID causes did not change significantly. Our race and ethnicity analysis showed SUID rates increased significantly for non-Hispanic Black infants from 2019 to 2020, widening the disparities between these two groups during 2017 to 2019. In 2020, <10 of the 3328 SUID had a COVID-19 code. CONCLUSIONS: Diagnositic shifting likely explained the increased SIDS rate in 2020. Why the SUID rate increased for non-Hispanic Black infants is unknown, but warrants continued monitoring. Interventions are needed to address persistent racial and ethnic disparities in SUID.