Global trends, projections, and inequalities in neonatal sudden infant death syndrome mortality attributable to risk factors from 1990 to 2021

Introduction

Sudden infant death syndrome (SIDS) is defined as the sudden, unexplained death of an infant younger than 1 year of age that remains unexplained after a thorough investigation, including a complete autopsy, examination of the death scene, and review of the clinical history (1). According to the Global Burden of Disease (GBD) 2021 estimates, approximately 27,199 deaths were attributed to SIDS globally in 2021 (2). With an estimated 140 million births worldwide in the same year, this corresponds to a measurable incidence, indicating a notable public health burden (3). In addition, SIDS imposes broader societal costs related to the allocation of public health resources, family care responsibilities, and non-economic consequences such as parental psychological stress (4). These considerations underscore the need for ongoing surveillance, further research, and the implementation of evidence-based interventions to reduce the incidence of SIDS and its associated burden.

The neonatal period represents a unique stage within infancy, characterized by rapid physiological adaptation after birth and the relative immaturity of multiple organ systems, which contributes to distinctive patterns of vulnerability and mortality in early life (5). Data from the GBD 2021 study indicate that ten risk factors are associated with neonatal SIDS, including behavioral risks, child and maternal malnutrition, short gestation, environmental and occupational risks, low birth weight and short gestation, air pollution, low birth weight, ambient particulate matter pollution, household air pollution from solid fuels, and particulate matter pollution (2). Few studies have applied a comprehensive analytical framework to examine temporal trends and project future patterns of SIDS attributable to common risk factors during the neonatal period at the global level. Understanding how the mortality burden of SIDS evolves over time and identifying the key drivers underlying these changes are essential for developing targeted prevention strategies and informing evidence-based health policies.

Using data from the GBD 2021 study, we systematically evaluated temporal trends and projected mortality from neonatal SIDS at the global level, with all analyses stratified by the ten risk factors. We further assessed their contributions and quantified socioeconomic inequalities in the distribution of neonatal SIDS mortality using the slope index of inequality (SII) and the concentration index. We present this article in accordance with the GATHER reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2026-0356/rc).

Methods

Data source

Data were obtained from the GBD 2021 study through the GBD Results Tool of the Global Health Data Exchange (GHDx) (6). In this study, neonatal SIDS was defined as SIDS occurring in infants aged <28 days. SIDS was identified according to the GBD 2021 disease definition (ICD-10: R95–R95.9; ICD-9: 798.0) and analyzed within the GBD age-specific estimation framework (7). This definition refers to an age-specific subset of SIDS rather than a distinct pathological entity. We extracted estimates of neonatal SIDS mortality rates and 95% uncertainty intervals (UI) attributable to ten risk factors, with rates expressed per 100,000 population. Socio-demographic development was assessed using the sociodemographic index (SDI)—a composite of income per capita, education, and fertility under 25. Locations were grouped into five SDI quintiles: low, low-middle, middle, high-middle, and high. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments.

Descriptive analysis

To comprehensively characterize the burden of neonatal SIDS attributable to the ten risk factors, we conducted descriptive analyses at the global, regional, and national levels. We visualized global mortality rates attributable to these factors from 1990 to 2021 and stratified the results by sex and SDI quintiles. This approach allowed us to assess temporal trends and highlighted disparities across different levels of socioeconomic development.

Joinpoint regression analysis

Joinpoint regression analysis was used to estimate the average annual percent change (AAPC) and corresponding 95% confidence intervals (CI) in the burden of neonatal SIDS attributable to the three risk factors from 1990 to 2021 across 21 GBD regions, five SDI quintiles, and 204 countries (8). Annual percent change (APC) with 95% CI was calculated for each segment to quantify temporal trends. A trend was considered increasing when the APC/AAPC and the lower bound of the 95% CI were above zero, decreasing when the APC/AAPC and the upper bound of the 95% CI were below zero, and otherwise stable (9).

Cross-country inequality analysis

The SII and the Concentration Index were used to quantify socioeconomic disparities in neonatal SIDS mortality at global. The SII measures absolute inequality by estimating the difference in mortality between the most and least advantaged groups using a weighted regression model across the full SDI distribution. Robust linear regression with iteratively reweighted least squares was applied to account for heteroscedasticity (10). The Concentration Index quantifies relative inequality based on the Lorenz curve, reflecting the extent to which mortality is concentrated among socioeconomically advantaged or disadvantaged populations (11).

Predictive analysis

To further assess the future burden of neonatal SIDS attributable to the risk factors, autoregressive integrated moving average (ARIMA) models were applied to project global trends in mortality rates and death counts among infants aged <28 days from 2022 to 2035.

Statistical analysis

All analyses and visualizations were conducted using R software (version 4.5.0) and the Joinpoint Regression Program (version 5.4.0), with a two-sided P<0.05 considered statistically significant. JD_GBDR (V2.22; Jingding Medical Technology Co., Ltd.) was used to generate some of the figures.

Results

Descriptive analysis of the mortality rates of neonatal SIDS

Global level

According to the GBD 2021 study, ten risk factors contribute to neonatal SIDS. In 2021, the global death rates of neonatal SIDS attributable to all risk factors combined were 33.38 per 100,000 in males and 22.97 per 100,000 in females, corresponding to 1,696 deaths in males and 1,095 deaths in females.

Among these risk factors, child and maternal malnutrition, low birth weight and short gestation, and behavioral risks were the leading contributors to neonatal SIDS mortality, with identical mortality rates. Each was associated with a mortality rate of 23.46 per 100,000 (95% UI: 10.59–34.52) in males and 23.19 per 100,000 (95% UI: 10.52–34.58) in females (Figure 1). Similarly, air pollution, particulate matter pollution, and environmental/occupational risks also showed identical mortality rates, each associated with a mortality rate of 7.11 per 100,000 (95% UI: 3.08–10.95) in males and 7.44 per 100,000 (95% UI: 3.08–11.74) in females.

Figure 1 Global death counts and death rates of neonatal sudden infant death syndrome attributable to risk factors in 2021.

Low birth weight alone was associated with a mortality rate of 22.19 per 100,000 (95% UI: 10.04–33.00) in males and 22.03 per 100,000 (95% UI: 9.97–32.96) in females. Short gestation alone was associated with a mortality rate of 9.49 per 100,000 (95% UI: 4.16–14.49) in males and 9.96 per 100,000 (95% UI: 4.35–15.26) in females. Household air pollution from solid fuels was associated with a mortality rate of 4.84 per 100,000 (95% UI: 1.85–8.08) in males and 5.30 per 100,000 (95% UI: 2.09–8.68) in females. Ambient particulate matter pollution was associated with a mortality rate of 2.27 per 100,000 (95% UI: 0.96–3.95) in males and 2.14 per 100,000 (95% UI: 0.90–3.72) in females.

Regional level

For all risk factors, in 1990, the highest neonatal SIDS death rate was observed in South Asia, whereas the lowest occurred in Tropical Latin America. By 2021, the highest rate had shifted to Western Sub-Saharan Africa, while the lowest was observed in High-income Asia Pacific.

Similar regional patterns were observed across several risk factors. For air pollution, environmental/occupational risks, and particulate matter pollution, identical distribution patterns were observed: in 1990, the highest neonatal SIDS death rates attributable to these risk factors were all observed in South Asia, whereas the lowest occurred in High-income Asia Pacific. By 2021, the highest rates for all three risk factors were observed in Western Sub-Saharan Africa, while the lowest remained in High-income Asia Pacific. An identical distribution pattern was also observed for behavioral risks, child and maternal malnutrition, and low birth weight and short gestation. In 1990, the highest neonatal SIDS death rates attributable to these three risk factors were likewise observed in South Asia, whereas the lowest occurred in Tropical Latin America. By 2021, the highest rates were observed in Western Sub-Saharan Africa, while the lowest remained in High-income Asia Pacific (Figure 2).

Figure 2 Heatmap of neonatal death rates attributable to risk factors for sudden infant death syndrome across SDI regions and 21 GBD regions in 1990 and 2021. GBD, Global Burden of Disease; SDI, sociodemographic index.

For the remaining risk factors, neonatal SIDS death rates also showed marked regional variation. In 1990, the highest rates attributable to ambient particulate matter pollution were observed in North Africa and the Middle East, whereas the lowest occurred in Tropical Latin America. For household air pollution from solid fuels, the highest rates were observed in South Asia, while the lowest occurred in High-income North America. For low birth weight, the highest rates were observed in South Asia, whereas the lowest occurred in Tropical Latin America. For short gestation, the highest rates were observed in South Asia, while the lowest occurred in Central Europe (Table 1). By 2021, the highest neonatal SIDS death rates attributable to ambient particulate matter pollution remained in North Africa and the Middle East, whereas the lowest shifted to High-income Asia Pacific. For household air pollution from solid fuels, the highest rates were observed in Oceania, while the lowest remained in High-income Asia Pacific. For short gestation, the highest rates were also observed in Oceania, whereas the lowest remained in Central Europe. In contrast, for low birth weight, the highest rates were observed in Western Sub-Saharan Africa, whereas the lowest remained in High-income Asia Pacific (Table 2).

National level

In 2021, across 204 countries, the spatial distribution of neonatal SIDS mortality attributable to certain risk factors exhibited similar patterns, as detailed below. For air pollution, environmental/occupational risks, and particulate matter pollution, the highest mortality rates attributable to these risk factors were all observed in South Sudan, whereas the lowest were consistently observed in Antigua and Barbuda. Similarly, behavioral risks, child and maternal malnutrition, and low birth weight and short gestation exhibited identical distribution patterns, with the highest attributable mortality rates in Tokelau and the lowest in Antigua and Barbuda (Figure 3).

Figure 3 Death rates of neonatal sudden infant death syndrome across different risk factors at the national level worldwide in 2021.

For the remaining risk factors, the mortality rate attributable to ambient particulate matter pollution was highest in Egypt and lowest in Antigua and Barbuda. The mortality rate attributable to household air pollution from solid fuels was highest in South Sudan and lowest in Puerto Rico. For low birth weight, the highest attributable mortality rate was observed in Tokelau, whereas the lowest occurred in Antigua and Barbuda. Finally, the mortality rate attributable to short gestation was highest in Afghanistan, while the lowest rates were jointly observed in North Macedonia, Slovenia, and Denmark (Figure 3).

Joinpoint regression analysis

Figure 4 showed consistent declining trends in global mortality rates of neonatal SIDS attributable to different risk factors from 1990 to 2021. Air pollution, environmental/occupational risks, and particulate matter pollution demonstrated identical temporal patterns, with an AAPC of −3.357 (95% CI: −3.498 to −3.216), while behavioral risks, child and maternal malnutrition, and low birth weight and short gestation exhibited identical declining trends, with an AAPC of −3.120 (95% CI: −3.235 to −3.004). Among the remaining risk factors, household air pollution from solid fuels showed the most pronounced decrease (AAPC =−3.820, 95% CI: −3.956 to −3.685), whereas ambient particulate matter pollution exhibited a relatively smaller decline (AAPC =−1.763, 95% CI: −1.947 to −1.579). Short gestation and low birth weight showed comparable reductions, with AAPCs of −3.032 (95% CI: −3.188 to −2.877) and −3.022 (95% CI: −3.137 to −2.907), respectively.

Figure 4 Joinpoint regression analysis of temporal trends in global death rates of neonatal sudden infant death syndrome attributable to different risk factors, 1990–2021. (A) Child and maternal malnutrition, low birth weight and short gestation, and behavioral risks. (B) Low birth weight. (C) Short gestation. (D) Air pollution, particulate matter pollution, and environmental/occupational risks. (E) Household air pollution from solid fuels. (F) Ambient particulate matter pollution.

Across most risk factors, mortality rates of neonatal SIDS exhibited consistent segmented temporal patterns from 1990 to 2021. Nine risk factors—behavioral risks, child and maternal malnutrition, low birth weight and short gestation, air pollution, environmental/occupational risks, particulate matter pollution, low birth weight, household air pollution from solid fuels, and short gestation—showed a similar trajectory, characterized by modest declines before 2005, accelerated reductions during 2005–2015, and a subsequent deceleration thereafter. In contrast, ambient particulate matter pollution followed a distinct pattern, with a moderate decline before 2005, a sharper decrease during 2005–2009, a temporary increase during 2009–2014, and a renewed decline thereafter. Overall, the most substantial reductions occurred during the mid-2000s to early 2010s.

Cross-country inequality analysis

The SII was negative across the ten examined risk factors in both 1990 and 2021, indicating that neonatal SIDS mortality remained disproportionately concentrated in lower-SDI regions. However, the magnitude of absolute inequality declined across all risk factors, suggesting a general reduction in absolute disparities over time.

In contrast, substantial socioeconomic inequalities in neonatal SIDS mortality persisted across the ten risk factors, as indicated by consistently negative concentration index values. Relative inequality remained largely stable for behavioral risks, child and maternal malnutrition, low birth weight and short gestation, and low birth weight. Inequality increased for ambient particulate matter pollution, with the concentration index declining from −0.08 (95% CI: −0.16, −0.00) in 1990 to −0.17 (95% CI: −0.24, −0.10) in 2021, and for household air pollution from solid fuels, from −0.65 (95% CI: −0.70, −0.60) to −0.72 (95% CI: −0.77, −0.67). Air pollution and environmental/occupational risks exhibited persistently high but relatively stable inequality. In contrast, short gestation showed a slight attenuation in inequality, with the concentration index changing from −0.49 (95% CI: −0.55, −0.41) in 1990 to −0.42 (95% CI: −0.48, −0.35) in 2021 (Figure 5).

Figure 5 Health inequality regression and concentration curves for neonatal sudden infant death syndrome attributable to different risk factors. (A) Child and maternal malnutrition, low birth weight and short gestation, and behavioral risks. (B) Low birth weight. (C) Short gestation. (D) Air pollution, particulate matter pollution, and environmental/occupational risks. (E) Household air pollution from solid fuels. (F) Ambient particulate matter pollution. Panels A-1 to F-1 show SII regression curves, and panels A-2 to F-2 show CI curves. CI, concentration index; SDI, sociodemographic index; SII, slope index of inequality.

Predictive analysis

Projected trends based on ARIMA models showed heterogeneous trajectories in neonatal SIDS mortality across the ten risk factors from 2022 to 2035. Overall, mortality rates attributable to most risk factors are expected to decline, although the pace of reduction varies considerably across factors.

For behavioral risks, child and maternal malnutrition, and low birth weight and short gestation, a relatively steep and sustained decline is projected, indicating faster reductions than those observed for most other risk factors. Low birth weight and short gestation, when examined separately, also showed downward trends, although the decline appeared more moderate. Mortality attributable to air pollution and environmental/occupational risks is projected to decline slowly while remaining at relatively high levels throughout the projection period. In contrast, ambient particulate matter pollution, particulate matter pollution, and household air pollution from solid fuels show clearer downward trends (Figure 6).

Figure 6 ARIMA-based projections of neonatal sudden infant death syndrome death rates attributable to different risk factors through 2035. (A) Child and maternal malnutrition, low birth weight and short gestation, and behavioral risks. (B) Low birth weight. (C) Short gestation. (D) Air pollution, particulate matter pollution, and environmental/occupational risks. (E) Household air pollution from solid fuels. (F) Ambient particulate matter pollution. ARIMA, autoregressive integrated moving average.

Discussion

SIDS in the neonatal period remains a significant global public health concern, with its associated mortality burden drawing increasing attention. However, comprehensive assessments of neonatal SIDS mortality, particularly those incorporating multiple risk factors, long-term trends, and socioeconomic inequalities, remain limited. Using data from the GBD 2021 study, this study provides the first comprehensive evaluation of temporal trends, cross-country inequalities, and risk factor-attributable mortality of neonatal SIDS over the past three decades, and further projects the burden through 2035.

Our findings highlight that child and maternal malnutrition, low birth weight and short gestation, and behavioral risks are the leading contributors to neonatal SIDS. For child and maternal malnutrition, several mechanisms may contribute to increased vulnerability to SIDS. Inadequate early-life nutrition, including insufficient breastfeeding, may reduce immune protection and increase susceptibility to infectious illnesses; recent evidence also supports an association between lack of breastfeeding and increased risks of pneumonia, diarrhea, and SIDS (12). Infection and inflammatory responses have also been proposed as contributors to SIDS pathogenesis in susceptible infants (13). In addition, micronutrient deficiencies—particularly magnesium deficiency—have been suggested to be associated with SIDS. Maternal magnesium deficiency may impair thermoregulation in the fetus, potentially through effects on brown adipose tissue, leading to temperature instability and increased vulnerability to SIDS (14). Low birth weight and short gestation reflect underlying developmental immaturity, particularly in immune and respiratory control systems, which may compromise infection tolerance and cardiorespiratory stability, thereby increasing vulnerability to fatal events such as SIDS (15). In addition, behavioral risks, such as maternal behaviors and postnatal caregiving practices, may further exacerbate vulnerability to SIDS. Behavioral risks, such as maternal smoking and unsafe sleep practices, are important contributors to SIDS (16). Maternal smoking, a well-established behavioral risk, has been associated with impaired immune regulation. In vitro studies have shown that cells from smokers produce significantly lower levels of the anti-inflammatory cytokine interleukin-10 compared with those from non-smokers. This reduction may compromise the ability to regulate infection-induced pro-inflammatory responses, thereby increasing susceptibility to SIDS (17). Sleep-related caregiving behaviors also play a critical role. Unsafe sleep practices, such as prone or side sleeping positions, soft bedding, bed-sharing, and overheating, have been consistently linked to an increased risk of SIDS (18). These behaviors may impair airway patency and reduce the infant’s ability to respond to hypoxic challenges during sleep, thereby increasing the likelihood of fatal events (19). In addition, environmental factors, such as air pollution, particulate matter pollution, and environmental/occupational risks, are also associated with neonatal SIDS mortality. Previous studies have suggested that exposure to ambient air pollutants may induce systemic inflammation, oxidative stress, and alterations in respiratory control, thereby increasing the risk of sudden death in vulnerable infants (20).

In addition, we observed that mortality rates were consistently higher in males than in females across all risk factors, suggesting a potential sex-related biological vulnerability. This disparity may be partly explained by hormonal differences, as testosterone levels are elevated in male infants during the peak period of SIDS. Elevated testosterone may enhance pro-inflammatory responses, thereby increasing susceptibility to SIDS (21).

We observed that two groups of risk factors—child and maternal malnutrition, low birth weight and short gestation, and behavioral risks; as well as air pollution, particulate matter pollution, and environmental/occupational risks—exhibited identical mortality estimates. This pattern arises from the hierarchical organization of the GBD comparative risk assessment framework, in which specific exposures are nested within broader risk categories (22). Consequently, when the attributable burden is summarized at the global level, hierarchically related risk factors may yield identical aggregated estimates, reflecting overlapping parent-child relationships rather than independent or additive effects.

Our analysis showed marked geographic heterogeneity in neonatal SIDS mortality attributable to risk factors, with the burden concentrated in lower-resource regions and countries. From both regional and national perspectives in 2021, the highest death rates for most risk factors were observed in Western Sub-Saharan Africa, with several countries such as South Sudan and Tokelau bearing particularly high burdens, whereas the lowest rates were observed in high-income regions such as High-income Asia Pacific, with countries such as Antigua and Barbuda and Denmark showing the lowest burden. Previous studies have shown that South Asia and Sub-Saharan Africa bear a disproportionate burden of low birth weight and preterm birth, as well as maternal and child undernutrition, which remain major public health challenges in these settings (23-25). These upstream risk distributions may partly explain the elevated neonatal SIDS mortality observed in these regions. A similar regional distribution was observed for air pollution, environmental/occupational risks, and particulate matter pollution, with South Asia and Western Sub-Saharan Africa consistently showing higher mortality rates. This may reflect the higher levels of environmental exposure in these regions. Previous studies have reported that South Asia experiences some of the highest levels of ambient air pollution globally (26), while many countries in Sub-Saharan Africa continue to face significant environmental and occupational health risks (27,28). The high levels of environmental pollution in these regions may partly explain the elevated mortality related to environmental risk factors.

Overall, our analysis revealed a sustained global decline in neonatal SIDS mortality attributable to multiple risk factors between 1990 and 2021. This pattern is consistent with previous studies reporting substantial reductions in neonatal mortality worldwide over the past three decades, largely driven by improvements in maternal and neonatal health care, expanded access to antenatal services, and strengthened public health interventions targeting modifiable risk factors (29). Advances in obstetric care, neonatal intensive care, and maternal nutrition programs have contributed to reductions in adverse birth outcomes such as preterm birth and low birth weight, which are closely linked to neonatal mortality (30,31). Notably, the most pronounced decline occurred between 2005 and 2015. This period coincided with intensified global efforts to improve maternal and child health under the Millennium Development Goals (MDGs) (32), which prioritized reductions in child mortality and improvements in maternal health. During this time, many countries expanded coverage of essential newborn care, improved access to skilled birth attendance, and strengthened maternal nutrition interventions (33). These initiatives likely contributed to the accelerated reductions in neonatal mortality observed during this period. However, the magnitude of decline varied across risk factors. Environmental-related risks such as air pollution and particulate matter pollution exhibited relatively smaller reductions, possibly reflecting persistent environmental exposures in many low- and middle-income countries (34). Rapid urbanization, industrial emissions, and continued reliance on polluting energy sources have limited improvements in ambient air quality in several regions (35). In contrast, mortality attributable to household air pollution from solid fuels showed a more pronounced decline, which may be associated with global efforts to promote cleaner household energy and reduce indoor air pollution exposure (36). These contrasting patterns suggest that interventions targeting household energy use may have achieved greater progress than broader environmental pollution control strategies.

The present study revealed persistent socioeconomic inequalities in neonatal SIDS mortality attributable to multiple risk factors across SDI levels. Consistently negative SII values indicate that deaths related to these risk factors remained disproportionately concentrated in lower-SDI regions. Although the magnitude of SII declined over time, suggesting a reduction in absolute inequality, the burden associated with these risk factors continues to be unevenly distributed across socioeconomic contexts. At the level of specific risk factors, relative inequalities persisted for several major determinants of neonatal SIDS, including behavioral risks, child and maternal malnutrition, and low birth weight and short gestation. These risk factors are closely associated with broader social determinants of health, such as maternal nutrition, access to prenatal care, and overall socioeconomic conditions. In many lower-SDI settings, limited access to quality antenatal care, higher prevalence of maternal undernutrition, and inadequate perinatal health services may contribute to the continued concentration of risk in disadvantaged populations (37,38). For behavioral risk factors, lower mortality observed in higher-SDI regions may partly reflect more effective maternal health education and public health campaigns, including smoking cessation programs during pregnancy and the promotion of safe infant sleep practices such as appropriate sleep positioning and sleep hygiene (39,40). Notably, inequalities associated with environmental risk factors—particularly ambient particulate matter pollution and household air pollution from solid fuels—showed evidence of increasing relative disparities over time. Environmental exposures are often unequally distributed across socioeconomic groups, with populations in lower-income regions more likely to experience higher levels of air pollution and limited access to cleaner energy sources (41,42). Such structural inequalities may explain the widening relative disparities observed for these environmental risk factors. Taken together, the persistence of socioeconomic disparities across multiple risk factors highlights the continuing influence of social and environmental determinants on neonatal SIDS mortality. Strengthening maternal and perinatal health services, improving health education, and reducing environmental exposures may be essential to further narrow these inequalities.

Projected trends indicate that mortality attributable to most neonatal SIDS risk factors will continue to decline between 2022 and 2035, although the pace of reduction varies across factors. Faster declines are projected for behavioral risks, child and maternal malnutrition, and low birth weight and short gestation, likely reflecting improvements in maternal health services, prenatal care, and nutrition interventions (30). In contrast, mortality related to air pollution and environmental or occupational risks is expected to decline more slowly and remain at relatively high levels, as environmental exposures are shaped by broader structural factors such as urbanization, industrial development, and energy transitions (34,35). Gradual reductions in particulate matter pollution and household air pollution may reflect progress in air quality policies and the transition to cleaner household energy sources (36). Overall, these projections indicate that further reductions in neonatal SIDS mortality will likely depend on continued improvements in maternal health as well as stronger efforts to mitigate environmental risks.

This study has several limitations. First, estimates were derived from the GBD 2021 database and are therefore subject to potential biases related to data availability and quality across regions. Second, the use of modeled estimates may introduce uncertainty despite the application of standardized GBD methodologies. Third, risk factor attribution analyses rely on comparative risk assessment frameworks that may not capture all contextual determinants of neonatal SIDS (43).

Conclusions

Neonatal SIDS mortality attributable to major risk factors has declined globally over the past decades, but substantial socioeconomic inequalities persist across SDI levels. Deaths related to behavioral, nutritional, and perinatal risk factors remain disproportionately concentrated in lower-SDI regions, reflecting persistent disparities in maternal health conditions and access to quality perinatal care. Although further reductions are projected for most risk factors through 2035, environmental exposures—particularly air pollution—may continue to contribute to a relatively higher burden. These findings highlight the need for integrated strategies that strengthen maternal and perinatal health services while addressing environmental determinants in order to reduce inequalities and further decrease neonatal SIDS mortality.

Acknowledgments

This study was generously supported by Jingding Medical Tech, to whom we extend our sincere gratitude. We especially thank them for providing authorization and technical support for the JD_GBDR software. The team at Jingding Medical Tech offered invaluable assistance in data processing.

During the preparation of this manuscript, an artificial intelligence-assisted tool was used solely for language polishing and improving the clarity of expression. The tool was not used for study conception or design, data collection, data analysis, interpretation of results, or the generation of scientific conclusions. All authors reviewed and edited the manuscript carefully and take full responsibility for the content of the article.

Footnote

Reporting Checklist: The authors have completed the GATHER reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2026-0356/rc

Peer Review File: Available at https://tp.amegroups.com/article/view/10.21037/tp-2026-0356/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2026-0356/coif). T.J serves as an unpaid committee memberships in the Xi’an Medical Association and the Shaanxi Medical Communication Society. Y.W. serves as an unpaid member of the Clinical Pharmacology Committee of the Shaanxi Pharmacological Society and the Pharmaceutical Science Popularization Committee of the Shaanxi Association for Health Promotion and Education. S.Z. serves as an unpaid member of the Mental Health Nursing Committee of the Shaanxi Nursing Association and the Pediatric Nursing Committee member of the Xi’an Nursing Association. G.Z. serves as a member of the Pediatric Nursing Committee of the Shaanxi Nursing Association and a standing committee member of the Pediatric Nursing Committee of the Xi’an Nursing Association. G.Y. serves as an unpaid member of the Preventive Health Care Committee of the Neonatology Branch of the Chinese Medical Doctor Association and a standing committee member of the Northwest Pediatric Critical Care Alliance. The other author has no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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