Determinants of Under-Five Child Mortality in Iran: A Systematic Review

Background: The under-ve child mortality is considered as one of the indicators of development and health of a population. The death of many children during this period is preventable. This study reviewed the determinants of child death in Iran. Methods: A systematic search in seven electronic databases and two search engines of all the studies that identied determinants of child mortality in any part of Iran or in the whole country were included, without any restriction of time or language of studies. To identify the studies, a combination of hand searching, gray literatures and bibliographies was also conducted. These sources and citations yielded a total of 512 articles; nevertheless, nally 32 articles ful ﬁ lled the inclusion criteria, then were reviewed and analyzed. Results: Amongst the 32 studies published between 2000 and 2019 in Iran, 22 studies were cross-sectional and 14 published in Farsi language. The associations between several factors (n=57) and the child mortality were examined. Factors such as ‘birth weight’, ‘mother’s literacy’, ‘socioeconomic status’, ‘delivery type’, ‘gestational age’, ‘pregnancy interval’, ‘place of residence’, ‘Immaturity’, ‘type of nutrition’, ‘father’s literacy’ and ‘child gender’ were the most important determinants of child mortality. Conclusions: Effective efforts with emphasis on identifying and managing the determinants of child mortality are essential to improve their health indicators.

Page 3/40 56 deaths per 1,000 live births in 1990 to 16 deaths in 2015 (8, 10). Despite the dramatic decline in child mortality, more than half of these deaths seem to be preventable (11,12).
Therefore, understanding and assessing the factors affecting the child mortality could be the rst step in planning to reduce the mortality and promoting the society health and life expectancy. In addition, with identifying these determinants, health policy makers can take more effective program and policies to reduce child mortality in each country or regions. Therefore, the goal of this study is to provide insights into some of determinants affecting mortality in Iran. The results of this study may provide additional information regarding modi able factors that may be useful in planning of intervention to promote child survival in country.

Criteria for considering studies for this review
We conducted a systematic literature review to identify all studies that assessed under-ve mortality determinants in Iran. Based on WHO de nition, data are presented in 3-year age groups: 0-28 days (neonatal mortality rate), younger than 1 year (infant mortality rate) and <5 years (Under-ve mortality rate) (25).
Since the determinants of mortality may be different in the under-ve age groups, and some existing studies have examined the determinants of mortality in the one to ve year age groups, researchers added another group (1-5 years as pre-school) to this classi cation (25).

Search strategy
Based on the inclusion criteria, we searched electronic databases: "PubMed", "Scopus", "Cochrane library databases", "Web of Science" "Google" and "Google scholar" on July 19, 2019. In the PubMed and In other databases, all the synonyms of "under-ve child mortality" were searched and afterward "Iran" was added to the search terms. This method was the most appropriate search in the present review, because of the well-known and comprehensive nature of the child mortality term.
To ensure that all the relevant studies including those published in Farsi (formal language of Iran) was identi ed; an electronic search in Farsi was conducted in Google and "Google scholar" as well as in the main national databases including "SID", "Magiran", using the translation of "under-ve mortality" and its various synonyms in Farsi and "Iran" as keywords. Additional searches for the bibliographies of the included studies were made. Reference lists of selected articles were also screened for additional publications and identi cation of the main experienced authors in the eld of study and connection with them to nd the most relevant surveys.
In a similar way, hand searching was conducted among highly relevant journals, grey literature, informal reports and documentation by the government or other agencies, thesis, research project, etc. All studies from different sources imported into EndNote ×9.

Study selection
The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) Flow diagram shows the process of identifying, reviewing, and selecting articles (Fig. 1). Studies that only examined the determinants of child mortality on a smaller place than a city, or only reported descriptive statistics on child mortality were excluded from the study.
At rst, 512 surveys were obtained through electronic and hand searching. All duplicate records (n=82) were deleted before the title and abstract screening process and 430 Records remained for further review. We reviewed the titles and abstracts of remaining papers and unrelated articles. Finally, 80 were obtained for the full text review to assess for eligibility. 28 studies that only reported a frequency for child mortality, examined the child mortality on a smaller scale than city, dissertations of published papers, articles without using the national databases, meeting abstract and editorial letter were excluded. Finally, 52 studies met the inclusion criteria for this review study, hence were utilized.

Quality assessment
Articles selected for analysis were assessed by two independent reviewers. For methodological validity, STROBE checklist were used. The checklist used in this study includes 22 items (score range:  which assess lucidity of the objectives and research questions of cohort, case-control, and crosssectional (combined) studies. Any disagreements that arose between reviewers were resolved through discussion. We exclude papers that scored lower than 16 in quality assessment. Since the number of articles in this eld was high, it seems possible to achieve high quality articles by selecting this cut point.
Meeting abstracts and editorial letters were excluded, too.

Data extraction and analysis strategy
Data extraction included speci c details about the study design, the sample size, analysis, ndings including factors associated with child mortality such as demographic, socioeconomic and health related factors and quality scores were extracted from the articles using a purposefully designed data extraction form (table 1). The studies included were developed for a diversity of objectives, used a variety of measures and methods and included study participants with different characteristics. This diversity made formal meta-analysis impossible. Therefore, the results of similar dimensions or aspects of social support were identi ed and grouped together and then the ndings were reported, compared and examined descriptively.

Description of the included studies
As shown in Table 2, of the 32 included studies, 22 studies (68.7%) were cross-sectional while 7 studies (22%) were case control design. In addition, two studies were performed as a time series (6.2%) and one ecological study (3.1%). Similarly, 14 out of the 32 papers (43.7%) were written in Farsi and the others in English. As gure2 shows the publication date of the included studies ranged from 2001 to 2019. Most studies conducted by data from years 2009-2014.
Moreover, out of the 32 studies, 8 studies were conducted at the country level and 24 studies at the provincial level. Most studies have examined determinants in age groups less than one year. The following gure 3 shows the number of studies by different age groups.

Determinant Of Child Deaths In Iran
The associations between several factors (n=57) and the child mortality were examined in reviewed studies. A summary of the results and their references are shown in Table 1. The association of 'birth weight' with mortality was examined in 14 studies, of which 1 studies did not nd a signi cant effect. In contrast, 'mother's literacy', which was examined in 15 studies, was discovered to be a signi cant factor associated with mortality in 10 studies. The 'socioeconomic status', was another factor which was examined frequently in the Iranian studies (n = 8 studies) and in 3 studies did not nd a signi cant relationship. Delivery type, which also was examined frequently (n = 13 studies), so as in 7 studies associations were signi cant but in 6 studies were not signi cant. The association between 'gestational ages' of the mothers with child mortality was also examined in 9 studies; in 2 studies didn't nd association with mortality. About 'pregnancy interval' in 50% of studies association were signi cant. Contrarily, 'mother's age 'was not associated with child mortality in more than 45.5% of the studies.
In addition, 'place of residence' in 6 studies were signi cant and in 5 studies didn't nd association. 'Immaturity' has been studied in only 6 studies, all of which have a signi cant relationship with child mortality. Also in all studies in which the relationship between the type of nutrition and child death has been reviewed, no signi cant relationship has been found between them. The association of 'father's literacy' in 6 studies were signi cant but in 4 studies weren't signi cant. 'Stillbirth' in 4 studies were examined and in all of them weren't signi cant. Thirteen studies have examined the relationship between 'child gender' and mortality; in 10 studies, this relationship has been signi cant. The relationship between 'abortion' (in 4 studies in total), 'birth rank' (in 7 studies in total) and 'multiple pregnancies' (in 3 studies in total) with child death in 3 studies of reviewed studies for each factor were signi cant. However, the relationship between birth rank and child mortality was not signi cant in 4 studies.
It is noteworthy that the relationship between some factors such as: father's smoking, mother's addiction, child age, father's age, mother's job, father's job, maternal care, total delivery beds, mother's BMI, housing ownership, health index settlement, high risk pregnancy, immaturity and child mortality has not been signi cant in all studies that have examined them.
Other factors discovered to be associated or not associated with child mortality in this review study, but studied less frequently in Iran were as follows were summarized in Table 2.
Health index settlement 1(100) High risk pregnancy 1(100) Understanding these determinants is of particular importance for implementing speci c interventions for each age group in order to effectively reduce the burden of mortalities in the country.
We found that birth weight exhibited more associations with child mortality. One of the indicators of a community's health status is the birth weight of newborns. This indicator is not only related to the quality of nutrition, health, care during pregnancy and the mother's social environment, but also to the process of normal growth of the child (59). Birth weight, as well as the gestational age, has a signi cant relationship with infant mortality and its components including malnutrition in the rst year of life, susceptibility to infections, respiratory distress and traumas during childbirth, and development of chronic noncommunicable diseases (NCDs). The lower the birth weight and the gestational age, the greater the chance of child death (60, 61). Numerous factors lead to low birth weight, including poor socioeconomic status, poor nutrition, anemia, various diseases, medications, obstetric complications, miscarriage and intermittent pregnancy (62, 63). The results of a study showed that some of the biological and psychological characteristics of mothers include maternal height, bleeding and poisoning during pregnancy, lack of maternal awareness of prenatal care, marital dissatisfaction, abnormal blood pressure, employment and weight gain less than 5 kg during pregnancy and pregnancy under the age of 20, lack of proper rest and mobility of the mother during pregnancy have a signi cant effect on low birth weight and need to be given more attention in birth control programs for low birth weight infants (64).
Mother's literacy, was discovered to be a signi cant factor associated with mortality in 67% of studies. Findings from Terra and Choe studies have shown an inverse relationship between maternal education and infant mortality (65, 66). A study in India showed that women's education through the variables of health awareness and determinants of reproductive behavior, such as the use of preventive health services, child nutrition, and child care, which are directly related to child death (67). Mothers with higher educational experience and better economic autonomy are likely to enjoy the resources required to maintain a healthy lifestyle and have better access to health services. Since promoting the level of education increases the level of employment, this increases the social status and increases the income and welfare of the family, and promotes family health. Therefore, it is suggested that special attention be paid to the education of young people, especially girls, as a primary solution to children's health in the form of long-term programs. The constructive role of women in raising and ensuring the health of children should always be considered. In addition, in order to encourage parents to study science, education planners should take appropriate measures.
We also found that socio-economic status and mother's literacy presented more associations with child mortality. Good socio-economic status reduces mortality by increasing access to available resources. In particular, parental education and family income are important indicators of the quality and quantity of resources that families can use to maintain their children's safety and health. Previous studies have shown that the appropriate socio-economic status and its elements increase the health and well-being of the child (68, 69). Many studies have also shown that poor socioeconomic status will increase child mortality (70)(71)(72). In a study on the determinants of infant mortality, the relationship between per capita incomes, per capita health expenditure, the rate of pediatric diarrhea treatment, maternal literacy rate and inequality based on the Gini coe cient showed an inverse relationship with infant mortality. According to this study, economic growth is the most important determining factor in child mortality and then the provision of health services is the second most important factor (73).
Iran's economy has entered its third consecutive year of recession due to a shock caused by three factors: sanctions, the oil market crisis and Covid-19. Iran's GDP in the end of 2019 has decreased due to the removal of US sanctions exemptions on the country's oil exports. High in ation due to the sharp devaluation of the national currency has put double economic pressure on low-income households. Many years of recession and high in ation have hampered household livelihoods. In 2018, the poverty rate in the country, according to the global poverty line, which is equivalent to purchasing power parity with the US $ 5.5, was 12.3 percent, which was 1.5 percent higher than the previous year. Inequality (in terms of Gini coe cient) was equal to 35.6 and its value has always been increasing after 2016. Socio-economic inequality also seems to be one of the most prominent factors in uencing the increase in child mortality in Iran. Extensive population-based policies (focusing on education, social welfare, the labor market, and tax policies) are needed to reduce inequalities, and in particular to improve the health of mothers and children (74).
Delivery type, which also was examined frequently, so as in 54% of studies associations were signi cant but in others were not. Cesarean delivery leads to potential injuries to the child and mother during surgery.
Doubling maternal mortality, the possibility of uterine rupture, increased postpartum hemorrhage and infection, prolonging the postpartum recovery period, and readmission are complications of this surgery for the mother. As well, repeated cesarean section are accompanied with complications such as adhesions abnormal placenta, Placenta Previa, hysterectomy, need to get more than 4 units of blood and mother's hospitalization in intensive care units (75,76). In addition, neonates born by cesarean section are more likely to be in the neonatal intensive care unit due to drastic complications. Their problems may even spread to childhood and they are more likely to develop diabetes, asthma, sepsis, thromboembolism, amniotic uid embolism autism and overweight (77,78).  to maintain the right interval between births in the future, which is the continuation of family planning programs and free and public access to contraceptives so that women can give birth to the number of children of their choice at appropriate intervals.
Mother's age was associated with child mortality in approximately 50% of the studies. According to Patel et al., The median age of marriage for mothers was 18, and more than half of mothers were married before reaching legal age. The high risk of neonatal death among young pregnant mothers is due to biological and psychosocial immaturity, as well as the chances of low birth weight babies being born (89). The results of another study showed that child mortality in mothers who married under the age of 15 was more than twice as high as that of married mothers between the ages of 20 and 24 (90).
All of reviewed studies revealed a signi cant relationship between immaturity and child mortality. A study conducted at the Department of Obstetrics and Gynecology at the University of London named premature birth as one of the leading causes of death and disease in developing countries (91). Today, despite the advances in medical science, the birth of premature infants is still considered as one of the major problems in our society. The birth of a premature baby, in addition to creating economic and psychological problems in the family, causes the loss of nancial and human resources and the death of children (92).
Also in all studies in which the relationships between the type of nutrition and stillbirth with child death have been reviewed, no signi cant relationships have been found between them. Despite the lack of correlation between these variables, it should be said that breastfeeding is the best choice for neonates.
Milk contains substances that are absorbable in terms of quality and quantity for the infants, provide energy and growth of the baby, breastfeeding reduces the incidence of hospitalization for the treatment of respiratory diseases and protects the infant from diarrhea due to enterococci, middle ear infections, allergies and type 2 diabetes (93,94). Regarding the factors related to the continuation of breastfeeding, studies showed that there is a relationship between the duration of breastfeeding and immaturity of the child. The breast milk of those mothers whose baby is born before 37 weeks of gestation is speci c to the premature baby and has a higher content of protein, minerals such as iron and defense factors than the milk of the newborn and is therefore more suitable for the premature baby (95).

Conclusion
Based on the results of this review, many studies have been conducted in Iran, but no study has systematically reviewed the results of those. pregnancy, this can be controlled the determinants and prevented deaths due to the involvement of these factors.
Parents' education through the variables of health awareness and determinants of reproductive behavior such as the use of preventive health services, child nutrition, child care of the patient that are directly related to child death. Parents' education reduces the risk of infant mortality, both directly and through other factors. Women's education is known to in uence child mortality due to health awareness and determinants of reproductive behavior such as the use of preventive health services, child nutrition, and sick childcare.
Boys' deaths are higher than girls in most parts of the world due to gender differences in genetic and biological structure. Boys are biologically weaker than girls and are more prone to disease and premature death. Therefore, special care in boys seems necessary.
Measures to improve the quality of education for young mothers and increase their awareness and quality of care for mothers, especially mothers who have experienced stillbirth or married at a young age, will be fruitful. In addition, with regard to accommodation, it seems that access to health facilities and facilities has increased, especially in recent years in rural areas, and this can be effective as a factor in reducing child mortality. Improvements in economic growth, education, housing, nutrition, health care and health measures also reduce child mortality.
According to the results of the study, it is suggested that measures be taken to improve the quality of education for mothers and young girls, increase their awareness, and improve the quality of maternal care, especially mothers who have experienced stillbirth or married at a young age. Considering the impact of those socio-economic factors that have the potential for change and intervention, such as parents' education, maternal age at marriage, housing hygiene, and maternal age at childbirth can be of great help in further reducing the gure. Planning to improve the quality of maternal and neonatal care, as well as the provision of advanced medical services can be effective in reducing infant mortality.

Limitations
To our knowledge, this is the rst systematic review determinants of death among under-5 mortality and covered the whole country. In addition, all studies conducted in the country were reviewed for this survey, but to select the highest quality articles, quality assessment was performed and poor quality articles were excluded. Despite these strengths, issues such as the classi cation of age groups under 5 years were the most important limitations of this study and to overcome these issues, appropriate measures were taken as mentioned before. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Competing interests
The authors declare that they have no competing interests.  Number of studies by age group