Avoidable deaths among children under 5 years of age: a review and Brazil’s model

Introduction

Background

The United Nations (1) listed the reduction of mortality in children under 5 years old among the goals for sustainable development for 2030. According to the World Health Organization (WHO) (2), the leading causes of preventable death in this age group are preterm birth complications, birth asphyxia/trauma, pneumonia, congenital anomalies, diarrhea, and malaria. Preventable death occurs when the fatality can be avoided through primary prevention (health promotion and immunization) and/or adequate health service assistance (accessible and efficient) (3,4).

Rationale and knowledge gap

In Brazil, the overall mortality rate in children has decreased over the last decades, reaching 13.7 per thousand live births among children under 5 years of age in 2020 (5,6).

Historically, the reduction in infant mortality has been due to sanitary measures, such as ensuring drinking water, to adequate care during prenatal care, childbirth, and childhood, as part of the goals of the Unified Health System, encompassing all levels of health care (7,8).

Nevertheless, the mortality rate for preventable causes in this population was 159 deaths per 100 thousand inhabitants in 2022, computing the ratio of deaths between avoidable and non-avoidable causes as equal to 1.7, which represents five avoidable deaths for every three non-avoidable ones, this means that about 40% of the total deaths in this age group could have been avoided (9).

Since 2006, the country has detailed a list of deaths from preventable causes, prepared by the Ministry of Health (MoH) (10). Although, there is a lack of studies at the national level regarding the identification of the main causes of avoidable deaths, especially in the child population, whose reduction, although gradual, is slow (6).

Objective

This article focuses on avoidable deaths aiming to answer the following questions: (I) “What are the leading causes of death in children in this age group?”; (II) “What are the trends from Brazil in the last 5 years (2018 to 2022)?”; and (III) “Do these trends vary with the population sizes of the city?”.

Methods

To answer the first question, a 10-year literature review, from October 2014 to September 2024, was performed using artificial intelligence (AI) through the tool ResearchRabbit (11). As a search provider, Biomedical & Life Sciences, powered by PubMed, was chosen. To find the most relevant articles published in this period, the following keywords were used: infant mortality, neonatal mortality, under-five mortality, health inequalities and infant mortality, preventable causes of child deaths, and global infant mortality trends.

To answer questions II and III, a descriptive study with secondary data registered on the Mortality Information System (MIS) portal, managed by the MoH (12), was conducted. A 5-year period, encompassing the coronavirus disease 2019 (COVID-19) pandemic and 2 preceding years were chosen to reduce bias in identifying the main causes of avoidable deaths.

The MIS variables used were date of birth, date of death, underlying cause of death, and municipality of residence (12). The age at death, calculated from the difference between death and birthdate, were dichotomized into less than 1 year of age and from 1 to less than 5 years of age. The underlying cause of death, was used to identify avoidable deaths, according to the official list of the MoH (10), namely: A17, A19, A33, A35 to A37, A80, B05 to B06, B16, B26.0, G00.0, P35.0, P35.3, A50, B20 to B24, P00 to P01, P02.2, P02.3, P02.7, P02.9, P04 to P05, P07, P22.0, P26, P52, P55.0, P55.1, P55.8, P57.9 e P77; P02.0, P02.1, P02.4 to P02.6, P03, P08, P10 to P15, P20 to P21, P24 to P24.2 e P24.4 to P24.9; P22.1, P22.8 to P23, P25 to P28, P35.1, P35.2, P35.4 to P39.9, P50 to P54, P58 to P61, P70 to P74, P75 to P78, P80 to P83 e P90 to P96; A15 to A16, A18, A30 to A32, A38 to A41, A46, A49, A70 to A74, E03.0; E03.1, E10 to E14, E70.0, E73.0, G00.1 to G03, G40 to G41, I00 to I09, J00 to J06, J12 to J18, J20 to J22, J38.4, J40 to J42, J45 to J47, J68 to J69, N39.0, Q90; A00 to A09, A20 to A28, A75 to A79, A82, A90 to A99, B50 to B64, B65 to B83, B99, D50 to D53, E40 to E64, E86, V01 to V99, W00 to W99, X00 to X09, X30 to X49, X85 to Y34, Y40 to Y69 and Y83 to Y84, according to the International Statistical Classification of Diseases and Related Health Problems (ICD-10) (13) and deaths from COVID-19 (ICD-10 = B342) from the date of vaccination approval for the age group under study, i.e., 09/16/2022 for children over 6 months of age (14).

The municipality was classified according to size in quintiles of the population distribution, based on data from the 2022 census, with the following intervals: <4,471, 4,472 to 8,344, 8,345 to 14,942, 14,943 to 30,654, and ≥30,655 inhabitants, for the 5,570 Brazilian municipalities (15). These quintile intervals were directly derived from the data source (15).

Specific mortality rates from avoidable causes per thousand inhabitants were determined for each year, according to the population size of the municipality of residence. The 10 most frequent causes of death in 2022, were selected and identified for the two age groups (less 1 year and from 1 to less 5 years) according to the year of decease occurrence. The most frequent causes of avoidable deaths, with a minimum of 2% occurrence, were also determined for each age group according to population size, given by population distribution quintiles in 2022. This value (2%) was elected according to the 10 most frequent causes in all quintiles evaluated.

This study, as it is secondary data in the public domain, does not require approval by the Ethics Committee for research with human beings (16).

Results

In this period, 193,162 deaths were recorded, and 141 records were excluded due to lack of information about the municipality of residence, leaving 193,021 in total for analysis, being 41,506 in 2018, 40,824 in 2019, 35,765 in 2020, 36,672 in 2021, and 38 (10) under 5 years of age in the period evaluated: 63.4% in 2018, 63.0% in 2019, 64.1% in 2020, 64.3% in 2021, and 64.0% in 2022.

The 10-year review, using ResearchRabbit (11), found too many articles, however only 14 (17-30) about the issue subject and just five about mortality causes (18,20,26,29,30), as presented below. On the 14, there is only one from Brazil (9), but this article focuses on comparing methods to identify gaps in health service performance.

Liu et al. (18), studying data from 2000 to 2015 among 194 WHO member states, identified preterm birth complications, intrapartum-related events, sepsis/meningitis, congenital abnormalities, and pneumonia as the leading causes of death among neonates. In this study, children between 1 and 59 months displayed pneumonia, diarrhea, injuries, malaria, and congenital abnormalities. This global study involved 194 WHO members and the estimative of cause-specific mortality fractions was calculated using a multinomial logistic regression.

Another study (20) for the same period, among children aged from 1 to 59 months from India showed prematurity or low birthweight, neonatal infections, birth asphyxia or trauma, non-communicable, congenital for neonates and pneumonia, diarrhea, injuries, non-communicable, and other infections.

United Nations International Children’s Emergency Fund (UNICEF) (26), reporting global data from 2019, identified malaria, pneumonia, diarrhea, human immunodeficiency virus (HIV), and tuberculosis as leading causes among children under 5 years of age.

Another global study (29), using data from 1990 to 2022, reported prematurity, pneumonia, birth asphyxia/trauma, malaria, diarrhea among children of the same age.

Furthermore, global data from the same period (30) highlighted infectious diseases, including pneumonia, diarrhea, and malaria.

Table 1 presents mortality rates from 2018 to 2022. The overall mortality rate among children aged less than 1-year decreases from 11.98‰ in 2018 to 9.90‰ in 2020, then increases to 11.5‰ in 2022. The same pattern was observed for specific preventable mortality rate, respectively 7.93‰ in 2018, 6.57‰ in 2020 and 7.34‰ in 2022. For children aged from 1 to less than 5 years old, the overall mortality rate tends to decrease from 2018 to 2020 and increases from 2020 to 2022, when it reaches its highest value (0.53‰). For specific preventable mortality rate, the same model was noted, reaching the highest value in 2022 (0.27‰). The overall mortality rate and specific preventable mortality rate in 2018, 2019, and 2020 were higher in municipalities of medium population size, but higher in municipalities of small population size in 2021 and 2022. In general, there is a decrease in rates over time for municipalities with populations between 4,472 and 30,654 inhabitants, but an increase in municipalities with <4,471 inhabitants and ≥30,655 inhabitants.

The 10 leading causes of avoidable death in children under 1 year of age were: bacterial sepsis of newborn, unspecified; respiratory distress syndrome of the newborn; neonatal aspiration syndrome, unspecified; congenital malformation of heart, unspecified; fetus and newborn affected by maternal hypertensive disorders; necrotizing enterocolitis in newborn; extreme immaturity; fetus and newborn affected by premature rupture of membranes; extremely low birth weight; fetus and newborn affected by other forms of placental separation and hemorrhage; and other ill-defined and unspecified causes of mortality (Figure 1).

Figure 1 Percentage distribution of the main underlying causes of avoidable death in children aged less 1 year by year of death. Brazil, 2018 to 2022. P36.9, bacterial sepsis of newborn, unspecified; P22.0, respiratory distress syndrome of newborn; Q24.9, congenital malformation of heart, unspecified; P00.0, fetus and newborn affected by maternal hypertensive disorders; P77, necrotizing enterocolitis in newborn; P07.2, extreme immaturity; P01.1, fetus and newborn affected by premature rupture of membranes; P07.0, extremely low birth weight; P02.1, fetus and newborn affected by other forms of placental separation and hemorrhage; R99, other ill-defined and unspecified causes of mortality.

Among children aged 1 to 5 years (Figure 2), the most frequent underlying cause were: pneumonia, unspecified; other ill-defined and unspecified causes of mortality; coronavirus infection, unspecified site; bacterial pneumonia, unspecified; sepsis, unspecified; congenital malformation of heart, unspecified; other gastroenteritis and colitis of infectious and unspecified origin; acute lymphoblastic leukemia; unspecified cause of accidental drowning and submersion; and bronchopneumonia, unspecified.

Figure 2 Percentage distribution of the main underlying causes of avoidable death in children aged 1 to 4 years by year of death. Brazil, 2018 to 2022. J18.9, pneumonia, unspecified; R99, other ill-defined and unspecified causes of mortality; B34.2, coronavirus infection, unspecified site; J15.9, bacterial pneumonia, unspecified; A41.9, sepsis, unspecified; Q24.9, congenital malformation of heart, unspecified; A09, other gastroenteritis and colitis of infectious and unspecified origin; C91.0, acute lymphoblastic leukemia; W74.9, unspecified cause of accidental drowning and submersion; J18.0, bronchopneumonia, unspecified.

Regarding population size, the most frequent causes of avoidable deaths) in children under 1 year of age (Figure 3) were: bacterial sepsis of newborn, unspecified, respiratory distress syndrome of newborn, and neonatal aspiration syndrome, unspecified, in all quintiles of distribution population size, with the lowest values in the municipalities of the 5^th quintile (≥30,655 inhabitants).

Figure 3 Percentage distribution of the main underlying causes of avoidable death in children under 1 year of age by population size. Brazil, 2022. P36.9, bacterial sepsis of newborn, unspecified; P22.0, respiratory distress syndrome of newborn; Q24.9, congenital malformation of heart, unspecified; P00.0, fetus and newborn affected by maternal hypertensive disorders; P07.2, extreme immaturity; R99, other ill-defined and unspecified causes of mortality; P77, necrotizing enterocolitis in newborn; P01.1, fetus and newborn affected by premature rupture of membranes; P07.0, extremely low birth weight; J18.9, pneumonia, unspecified; A41.9, sepsis, unspecified; P96.9 condition originating in the perinatal period, unspecified.

Figure 4 shows that in children aged 1 to 5 years, the three most frequent causes. Coincides in all population sizes, with a lower proportion for the municipalities of the third quintile (8,345 to 14,942 inhabitants). The high proportion (6.2%) of preventable deaths due to other ill-defined and unspecified causes in small municipalities (<4,471 inhabitants) is remarkable.

Figure 4 Percentage distribution of the main underlying causes of avoidable death in children aged 1 to 4 years by population size. Brazil, 2022. J18.9, pneumonia, unspecified; R99, other ill-defined and unspecified causes of mortality; B34.2, coronavirus infection, unspecified site; J15.9, bacterial pneumonia, unspecified; A41.9, sepsis, unspecified; A09, other gastroenteritis and colitis of infectious and unspecified origin; C91.0, acute lymphoblastic leukemia; G40.9, epilepsy, unspecified; V44.6, occupant of an automobile (car) injured in a collision with a heavy transport vehicle or a bus—passenger traumatized in a traffic accident; Q24.9, congenital malformation of heart, unspecified; W69.8, drowning and submersion in natural waters—other specified locations; D68.9, coagulation defect not specified; Q05.9, spina bifida, unspecified; Q44.2, atresia of bile ducts; V43.6, occupant of a car [car] injured in a collision with a car [car], ‘pick up’ or pickup truck; W74.9 unspecified cause of accidental drowning and submersion; Q90.9, down syndrome, unspecified.

Discussion

The 10-year review found few articles on the leading causes of death in children aged under 5 years. Most approach and/or discuss mortality, but did not directly address the causes of death. Although, the majority utilized the WHO database, applying for different cuts of age, time, and/or geographical space. Only one used original survey (20), for the entire country of India. However, comparison with data from other studies needs to be cautious, because of the possible difference in methods and environmental, socioeconomic, and sociodemographic conditions, further health service assistance and the magnitude of the problem.

In general, the common leading causes of death for children aged less than 5 years old were malaria, pneumonia, and diarrhea (20,26,29). Even so, for children aged from 1 month to less than 1 year (18), malaria, pneumonia, diarrhea, injuries, and congenital abnormalities were shown. For neonates (aged less than 1 month), the same study (18) pointed out preterm birth complications, intrapartum-related events, sepsis/meningitis, congenital abnormalities, and pneumonia. India study (20) displayed similar causes: prematurity or low birthweight, neonatal infections, birth asphyxia or trauma, and noncommunicable, congenital. This study (20) also reported, for children aged 1 to 59 months, pneumonia, diarrhea, injuries, non-communicable, and other infections, but the rate is almost three times higher than in Brazil. Despite the strong similarity of the causes of death, the non-use of the ICD-10 (13) compromises the comparison between studies.

It is important to point out the decline in mortality rates in children under 5 years of age, as pointed out by some studies (19,29,30), with emphasis on the identification of high mortality clusters, rates, and trends (20,22,23,29), highlighting Sub-Saharan Africa (29). In Brazil, this study points out that the total mortality rate was 11.05‰ among children under 1 year of age and 0.53‰ among children aged from 1 to less than 5 years in 2020. These values are lower than the United Nations’ goals for 2030 (1), as well as the preventable mortality rate, that were 7.34 and 0.27, respectively for the same age intervals.

Brazilian’s models, using ICD-10 (13), showed death evolution from 2018 to 2022 and the variation with the population size of the city. The mortality rate due to avoidable deaths in the study period showed little variation in the group of children evaluated, reaching 4.2–4.5 times more among children under 1 year of age compared to those between 4 and 5 years of age.

Municipalities of medium population size (between 8,345 and 14,942 inhabitants) presented a higher overall mortality rate and specific preventable rate in 2018, 2019, and 2020, with decrease over time. Municipalities of small population size (<4,471) presented the highest rates in 2021 and 2022, as well as municipalities with ≥30,655 inhabitants. Small municipalities, in general, do not have or have small hospitals, which are characterized by low performance. The performance tends to improve in medium-sized hospitals, and more in large-sized hospitals, whose number of beds increases with the increase in the population of the municipality (31). However, large cities are characterized by an increase in population in the peripheries and inequality of income and access to public services, including health, which explains the higher rates during the pandemic of COVID-19.

Considering 2018 as a basic line, the present study shows significant trend of reduction of “respiratory distress syndrome of newborn” and “congenital malformation of heart, unspecified”, and increase of “necrotizing enterocolitis of newborn” and “extreme immaturity of newborn”, over time, among the top 10 causes of preventable death in children under 1 year of age. The reduction of “respiratory distress syndrome of newborn”, caused by pulmonary immaturity and surfactant deficiency, could be mainly avoided by antenatal care, ventilation strategies, adequate timing of umbilical cord clamping (32,33). “Congenital malformation of heart, unspecified” is associated principally to prematurity and pregnancy history (34). The reduction in both causes could be explained by the constant care with women health in the public service (35). Otherwise, the increase of “necrotizing enterocolitis of newborn”, caused by immaturity and inability to digest other foods instead of breast milk, among other inabilities (36), could be explained in part, for the reduction of breastfeeding (37). Already, the “extreme immaturity of newborn” results from maternal health, obstetric history, pregnancy complications, or lifestyle factors (38). Although discrete, these increases are worrying and alert the health system to these causes. In 2022, the 10 most frequent causes of death in children under 1 year of age were, in descending order: bacterial sepsis of newborn, unspecified; respiratory distress syndrome of newborn; neonatal aspiration syndrome, unspecified; fetus and newborn affected by maternal hypertensive disorders; necrotizing enterocolitis in newborn; extreme immaturity; fetus and newborn affected by premature rupture of membranes; extremely low birth weight; fetus and newborn affected by other forms of placental separation and hemorrhage; and other ill-defined and unspecified causes of mortality.

From 2018 to 2022, children between 1 and less than 5 years old showed 21% of deaths reduction by “other gastroenteritis and colitis of infectious and unspecified origin” and increase of 36% by “unspecified cause of accidental drowning and submersion”. In this case, gastroenteritis and colitis are associated with undetermined or unknown infectious agents, usually transmitted by water. The reduction can be explained by improved water supply, sewage treatment, and rotavirus vaccination (39). On the other hand, the child’s greater mobility and lack of supervision also increase the chance of accidents, such as drowning, which showed a significant increase over time in the study. Lack of supervision and swimming ability are the most common causes of drowning and submersion accidents (40).

In 2022, in the age group between 1 and less than 5 years, the most frequent causes of preventable deaths were pneumonia, unspecified: other ill-defined and unspecified causes of mortality; coronavirus infection, unspecified site; bacterial pneumonia, unspecified; sepsis, unspecified; congenital malformation of the heart, unspecified; other gastroenteritis and colitis of infectious and unspecified origin; acute lymphoblastic leukemia; unspecified cause of accidental drowning and submersion; and bronchopneumonia, unspecified. Children at this age are more exposed to outdoor environments, especially in preschools, being more vulnerable to infectious diseases, such as pneumonia and sepsis.

It is remarkable the appearance of “other ill-defined and unspecified causes of mortality” among the 10 leading causes of death in the population studied. Although the MIS (41) is reliable and the percentages of R99 are low, there are regional, socioeconomic, and healthcare differences, that still compromise the classification of the cause of death, requiring the use of updated correction factors. For example, population may have limited access to health services, and doctors may not have resources to identify the cause of death. However, in recent years the updated correction research has not happened.

In 2022, among children under 1 year of age, bacterial sepsis of newborn, unspecified was the most frequent cause of avoidable deaths, ranging from 6.8% in larger municipalities to 8.0% in smaller municipalities, which also had the highest frequency of deaths due to respiratory distress syndrome of newborn (5.9%). Deaths due to neonatal aspiration syndrome, unspecified, were higher (4.6%) in municipalities with populations between 4,472 and 8,344 inhabitants.

Older children, between 1 and 5 years of age, died mainly from respiratory diseases, highlighting COVID-19, ill-defined causes and external causes, in particular traffic accidents and drowning. Small municipalities had higher frequencies of deaths from septicemia. Again, the characteristics of health assistance (31) could explain these differences, as well as higher occurrences of “bacterial sepsis of newborn, unspecified” and “respiratory distress syndrome of newborn”. Both causes are associated with delivery care. Physical coexistence among children is greater in smaller municipalities, mainly due to greater proximity to the neighborhood and public safety (42).

About COVID-19, it is important establish that pandemic as Public Health Emergency of National Importance, in Brazil, began in Feb 20, 2020 and ended in Apr 22, 2022. In this period, three peaks of mortality were observed, the highest being in early 2020, when the immunization of the population began, with a significant drop in the third wave (9). Currently, vaccination against COVID-19 is part of the National Immunization Program (43).

Children under 1 year of age, especially in the first semester of life, are less exposed to external contacts, having more protection against COVID-19, despite Brazil occupy the second place in the world ranking of mortality, corresponding to 661,907 deaths at the end of emergency period (44).

In this study, the use of AI was a limitation for article search. While AI tool (11) accelerated initial literature discoveries, their limitations in structured and standardized indexing require complementary strategies. The AI identified broad trends, such as preventable causes linked to infectious diseases (e.g., diarrheal illnesses) and perinatal complications, consistent with the Global Burden of Disease Study (45). However, regional databases like Latin American and Caribbean Literature in Health Sciences (LILACS) and Scientific Electronic Library Online (SciELO), prioritized through EndNote’s search filters, were critical for contextualizing Brazil’s 60% reduction in under-five mortality [1990–2015]. França et al. (46), for example, attributed this decline to improved sanitation and vaccine coverage—insights only attainable through localized data. EndNote XXI (47), a reference management software integrated with PubMed/MEDLINE (National Library of Medicine) and with controlled vocabulary, to systematically screen and organize citations in a context-specific ensuring precision. Thus, combining AI with structured tools like EndNote XXI and regionally curated databases balances efficiency with scholarly rigor, as most of the studies identified that are not very specific by age, region, and cause of death.

Even the options for advanced search to combining multiple terms, the options for “Boolean operators” (AND, OR, NOT), the platform also offers the possibility of input an article of the user interest as first option to initiate the search. This offer is recent and was not available when our search was done. “ResearchRabbit” as scientific technique cannot be reproduced. Besides updates, it also used the AI as feedback every search time according to user. This study was limited by the lack of standardization of keywords in the literature, making it difficult to identify articles of interest in the area, as most of the studies identified use databases that are not very specific by age, region, and cause of death. Even so, it allows us to identify the main preventable causes of death.

Another limitation refers to the possibility of underestimated deaths from COVID-19, especially due to the lack of knowledge of the disease at the beginning of the pandemic, and lack of tests following.

Conclusions

For children under 5 years of age, avoidable causes of death are the causes sensitive to: immunoprevention, adequate health care for women during pregnancy and childbirth, for the fetus and newborn, diagnostic and treatment actions, and health promotion. This study identifies the primary causes of avoidable deaths in this age group, emphasizing the need to target investments in diagnostic capabilities and treatment actions. Additionally, it highlights the challenges associated with health promotion, particularly in addressing external causes of death, as well as ensuring rapid responses to pandemics, such as COVID-19. It is noteworthy that COVID-19, while not among the top 10 causes of death in children under 1 year of age, ranks among the 30 most frequent causes. The disease predominantly affects children under 6 months of age, for whom immunization is not yet available. This finding underscores the critical importance of early diagnosis and emergency treatment in mitigating its impact. Considering the need to reduce deaths from preventable causes, it is essential to monitor evolution and identify the primary contributors to these deaths, providing support for public policies planning. This encompasses the establishment of localized goals tailored to specific regional and demographic needs, where traditional interventions such as immunization, access to safe water and nutritious food, and the provision of high-quality care by well-trained health professionals are still essential. Specifically for Brazil, whose mortality rates are among the lows, but which still has great regional iniquities, and which has the Unified Health System, it is essential to settle between the three levels of government (federal, state and municipal) on diagnosis (magnitude and rates) and goals at the local level for the reduction of the main preventable mortality rates for children under 5 years of age, initially. Beyond these basic measures, the level of healthcare system development and scientific advancement play a pivotal role in shaping the list of avoidable causes of death, which varies across countries and regions. A stratified approach that considers three distinct ages groups (I) neonates (0 to less than 1 month), (II) infants (1 month to less than 1 year), and (III) young children (1 to less than 5 years), is crucial for tailoring strategies to address the unique vulnerabilities within each cohort. Finally, it is essential to continue studies with increasingly robust data to effectively drive the reduction of preventable infant deaths. For future studies, it is recommended that age be stratified into three groups (<1, 1 to 11, and 12 to 59 months), the use of the ICD-10 to classify causes of death, the use of avoidable death as keyword, and regional courts that allow better identification of causes, with the purpose of support the planning and evaluation of local health policies.

Acknowledgments

None.

Footnote

Peer Review File: Available at https://pm.amegroups.com/article/view/10.21037/pm-24-96/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://pm.amegroups.com/article/view/10.21037/pm-24-96/coif). The authors have 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.

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References

1. United Nations. Take Action for the Sustainable Development Goals. 2015 [accessed 2024 Sep 15]. Available online: https://www.un.org/sustainabledevelopment/sustainable-development-goals/
2. World Health Organization. Children: improving survival and well-being. 2020 [accessed 2024 Sep 15]. Available online: https://www.scirp.org/reference/referencespapers?referenceid=3393391
3. Organisation for Economic Co-operation and Development. Avoidable mortality: OECD/Eurostat lists of preventable and treatable causes of death (January 2022 version). 2022 [accessed 2025 Apr 18]. Available online: https://www.oecd.org/content/dam/oecd/en/data/datasets/oecd-health-statistics/avoidable-mortality-2019-joint-oecd-eurostat-list-preventable-treatable-causes-of-death.pdf
4. World Health Organization. About the WHO Mortality Database. 2025 [accessed 2025 Apr 18]. Available online: https://platform.who.int/mortality/about/about-the-who-mortality-database
5. Instituto Brasileiro de Geografia e Estatística. Taxa de mortalidade infantil por mil nascidos vivos - Brasil - 2000 a 2015. 2021 [accessed 2024 Sep 15]. Available online: https://brasilemsintese.ibge.gov.br/populacao/taxas-de-mortalidade-infantil.html
6. Moura EC, Cortez-Escalante J, Lima RTS, et al. Mortality in children under five years old in Brazil: evolution from 2017 to 2020 and the influence of COVID-19 in 2020. J Pediatr (Rio J) 2022;98:626-34. [Crossref] [PubMed]
7. Victora CG, Barros FC. Infant mortality due to perinatal causes in Brazil: trends, regional patterns and possible interventions. Sao Paulo Med J 2001;119:33-42. [Crossref] [PubMed]
8. Ministério da Saúde. Sistema Único de Saúde – SUS. 2025 [accessed 2025 Apr 20]. Available online: https://www.gov.br/saude/pt-br/sus
9. Moura EC, Cortez-Escalante J, Cavalcante FV, et al. Covid-19: temporal evolution and immunization in the three epidemiological waves, Brazil, 2020-2022. Rev Saude Publica 2022;56:105. [Crossref] [PubMed]
10. Malta DC, Sardinha L, Moura L, et al. Atualização da lista de causas de mortes evitáveis por intervenções do Sistema Único de Saúde do Brasil. Epidemiol Serv Saúde 2010;19:173-6.
11. ResearchRabbit. Research platform. [Accessed 2024 Sep 15]. Available online: https://www.researchrabbit.ai/
12. Ministério da Saúde. Sistema de Informação sobre Mortalidade – SIM. 2023 [accessed 2024 Sep 21]. Available online: https://opendatasus.saude.gov.br/dataset/sim
13. World Health Organization. ICD-10 Version:2019. 2019 [accessed 2024 Sep 24]. Available online: https://icd.who.int/browse10/2019/en#/II
14. Agência Nacional de Vigilância Sanitária - Anvisa. Covid-19: Anvisa aprova vacina da Pfizer para crianças entre 6 meses e 4 anos. 2021 [accessed 2024 Sep 24]. Available online: https://www.gov.br/anvisa/pt-br/assuntos/noticias-anvisa/2022/covid-19-anvisa-aprova-vacina-da-pfizer-para-criancas-entre-6-meses-e-4-anos
15. Tabnet. População não mais em uso. Veja no final desta página, o link para a população atual. 2004 [accessed 2024 Sep 24]. Available online: http://tabnet.datasus.gov.br/cgi/tabcgi.exe?ibge/cnv/projpopuf.def
16. Conselho Nacional de Saúde. Resolução n. 510 CONEP, de 07 de abril de 2016. 2016 [accessed 2024 Sep 30]. Available online: https://www.gov.br/conselho-nacional-de-saude/pt-br/atos-normativos/resolucoes/2016/resolucao-no-510.pdf/view
17. Sharrow D, Hug L, You D, et al. Global, regional, and national trends in under-5 mortality between 1990 and 2019 with scenario-based projections until 2030: a systematic analysis by the UN Inter-agency Group for Child Mortality Estimation. Lancet Glob Health 2022;10:e195-206. [Crossref] [PubMed]
18. Liu L, Oza S, Hogan D, et al. Global, regional, and national causes of under-5 mortality in 2000-15: an updated systematic analysis with implications for the Sustainable Development Goals. Lancet 2016;388:3027-35. [Crossref] [PubMed]
19. Dias BAS, Santos ETD. Neto, Andrade MAC. Classification systems for avoidability of infant deaths: different methods, different repercussions? Cad Saude Publica 2017;33:e00125916. [Crossref] [PubMed]
20. Changes in cause-specific neonatal and 1-59-month child mortality in India from 2000 to 2015: a nationally representative survey. Lancet 2017;390:1972-80. [Crossref] [PubMed]
21. Rasella D, Basu S, Hone T, et al. Child morbidity and mortality associated with alternative policy responses to the economic crisis in Brazil: A nationwide microsimulation study. PLoS Med 2018;15:e1002570. [Crossref] [PubMed]
22. Burstein R, Henry NJ, Collison ML, et al. Mapping 123 million neonatal, infant and child deaths between 2000 and 2017. Nature 2019;574:353-8. [Crossref] [PubMed]
23. Mejía-Guevara I, Zuo W, Bendavid E, et al. Age distribution, trends, and forecasts of under-5 mortality in 31 sub-Saharan African countries: A modeling study. PLoS Med 2019;16:e1002757. [Crossref] [PubMed]
24. Szwarcwald CL, Almeida WDS, Teixeira RA, et al. Inequalities in infant mortality in Brazil at subnational levels in Brazil, 1990 to 2015. Popul Health Metr 2020;18:4. [Crossref] [PubMed]
25. Jullien S, Huss G, Weigel R. Supporting recommendations for childhood preventive interventions for primary health care: elaboration of evidence synthesis and lessons learnt. BMC Pediatr 2021;21:356. [Crossref] [PubMed]
26. United Nations International Chidren’s Emergency Fund. Childhood diseases. New York: UNICEF. 2023 [accessed 2024 Oct 1]. Available online: https://www.unicef.org/health/childhood-diseases
27. Binagwaho A, VanderZanden A, Garcia PJ, et al. Cross-country analysis of contextual factors and implementation strategies in under-5 mortality reduction in six low- and middle-income countries 2000-2015. BMC Pediatr 2024;23:652. [Crossref] [PubMed]
28. García PJ, Williams AL, Carcamo MH, et al. Lessons from Peru to reduce under-5 mortality: understanding program implementation and context. BMC Pediatr 2024;23:646. [Crossref] [PubMed]
29. United Nations Inter-Agency Group for Child Mortality. Estimation levels & trends in child mortality: report 2023. 2024 [accessed 2025 Apr 29]. Available online: https://www.defeatdd.org/resources/reports/un-igme-child-mortality-2023-report/
30. United Nations International Children’s Emergency Fund. Under-five mortality. 2024 [accessed 2024 Oct 1]. Available online: https://data.unicef.org/topic/child-survival/under-five-mortality/
31. Panitz LM, Prata DN, Rodrigues W. Analysis of the performance of public and private hospitals serving the Brazilian Unified National Health System. Cad Saude Publica 2024;40:e00156023. [Crossref] [PubMed]
32. Grion CMC, Kauss IAM, Cardoso LTQ, et al. Treatment of acute respiratory distress syndrome using the recommendations of the Brazilian Consensus of Sepsis in an ICU of a teaching hospital. Critical Care 2005;9:92.
33. Sweet DG, Carnielli VP, Greisen G, et al. European Consensus Guidelines on the Management of Respiratory Distress Syndrome: 2022 Update. Neonatology 2023;120:3-23. [Crossref] [PubMed]
34. Madruga I, Moraes TD, Prado C, et al. Associated factors with congenital heart disease in the most populated state of Brazil between 2010 and 2018. Int J Cardiovasc Sci 2023;36:e20210283.
35. Saúde da mulher na gestação, parto e puerpério. 2019 [accessed 2025 Apr 29]. Available online: https://atencaoprimaria.rs.gov.br/upload/arquivos/202001/03091259-nt-gestante-planificasus.pdf
36. National Institutes of Health. What causes necrotizing enterocolitis (NEC)? 2021 [accessed 2025 May 2]. Available online: https://www.nichd.nih.gov/health/topics/nec/conditioninfo/causes#:~:text=In%20premature%20infants%2C%20the%20cause,they%20do%20not%20usually%20live
37. Secretaria-Geral. Amamentação exclusiva nos 6 primeiros meses só atinge 38,6% das crianças brasileiras. 2024 [accessed 2025 May 2]. Available online: https://www.gov.br/secretariageral/pt-br/consea/noticias/2017/amamentacao-exclusiva-nos-6-primeiros-meses-so-atinge-38-6-das-criancas-brasileiras#:~:text=Na%20Semana%20Mundial%20do%20Aleitamento,seis%20primeiros%20meses%20de%20vida
38. Taylor GL, O'Shea TM. Extreme prematurity: Risk and resiliency. Curr Probl Pediatr Adolesc Health Care 2022;52:101132. [Crossref] [PubMed]
39. Veras LDL, Soares LWF, Silva Neto MR, et al. Diarrhea and gastroenteritis of presumed infectious origin: analysis of the epidemiological profile in the regions of Brazil from 2012 to 2021. Research Society and Development 2022;11:e52711730295.
40. Imamura JH, Troster EJ, Oliveira CA. What types of unintentional injuries kill our children? Do infants die of the same types of injuries? A systematic review. Clinics (Sao Paulo) 2012;67:1107-16. [Crossref] [PubMed]
41. Moura EC, Cortez-Escalante JJ. Monitoramento de indicadores de qualidade dos Sistemas de Informações de Mortalidade (SIM) e Nascidos Vivos (Sinasc), nos anos 2000, 2005 e 2010. In: Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Análise de Situação de Saúde. Saúde Brasil 2011 Uma análise da situação de saúde e a vigilância da saúde da mulher. Brasília: Ministério da Saúde; 2012:401-18.
42. Cerqueira D, Bueno S, Caballero B, et al. Retrato Dos Municípios Brasileiros. 2024 [accessed 2025 Apr 28]. Available online: https://www.ipea.gov.br/atlasviolencia/arquivos/artigos/9277-atlasviolencia2024retratodosmunicipiosbrasileros.pdf
43. Ministério da Saúde. Programa Nacional de Imunizações. 2024 [accessed 2025 Apr 28]. Available online: https://www.gov.br/saude/pt-br/acesso-a-informacao/acoes-e-programas/pni
44. Worldometers. Coronavirus Cases. 2020 [cited 2020 June 19]. Available online: https://www.worldometers.info/coronavirus/
45. Global, regional, national, and selected subnational levels of stillbirths, neonatal, infant, and under-5 mortality, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet 2016;388:1725-74. [Crossref] [PubMed]
46. França EB, Lansky S, Rego MAS, et al. Leading causes of child mortality in Brazil, in 1990 and 2015: estimates from the Global Burden of Disease study. Rev Bras Epidemiol 2017;20:46-60. [Crossref] [PubMed]
47. Clarivate Analytics. EndNote XXI (Version 21.0). 2023. Available online: https://support.clarivate.com/Endnote/s/article/Download-EndNote?language=en_US