Background

In Ethiopia, both under-five and infant mortality rates significantly declined during the past decades [1], this might be as a result of the different health initiatives, such as expansion of health extension program in the country during this period [2]. However, child mortality rates in the country are among the highest in the world and about one in every 21 and 15 Ethiopian children dies before his/her first and fifth birthday, respectively [3]. Under-five mortality rate in Southern Nations, Nationalities and People’s Region (SNNPR), where the study conducted is among the highest in the country [1].

Many factors have been implicated for high under-five mortality in developing countries in general and in Ethiopia in particular. For example, children are thought to be dying owing to deliveries attended by untrained traditional birth attendants, relatives and neighbors at home [1], a practice that may present risks to both the mother and the newborn. Even though some are skeptical about the association between use of maternal and child health services and survival in developing countries, partly because of lack of health care service quality [4, 5], many studies support the positive association between health care service use, such as institutional delivery and maternal and child mortality [6, 7]. Place of delivery is also found to be associated with early childhood illnesses such as neonatal tetanus [8]. However, protective effect of institutional delivery on under-five mortality was not demonstrated by studies conducted in Ethiopia [9, 10]. It is possible to argue that this lack of association may be as a result of limited quality of health care services, in many developing countries which remains questionable [4, 5].

As a strategy for improved maternal and child survival, the World Health Organization (WHO) recommends a pregnant mother to attend at least four prenatal visits during her pregnancy [11]. This was supported by studies, that demonstrated the significant effect of antenatal care (ANC) service utilization on survival of children [6, 12]. However, effects of ANC and institutional delivery services may vary depending on the level of quality of services being provided.

Immunization may be one of the effective child-survival interventions to date as it addresses diseases which contribute significantly to high under-five mortality; including neonatal tetanus, whooping cough, polio and measles [13]. Immunization status of a child was shown to be an important factor for under-five mortality [7]. However, such conclusions were not made by other studies [14, 15]. Besides, the effect was shown to be higher in communities with low socioeconomic status [16], indicating that its effect is context dependent.

In addition to immunization, Vitamin A supplementation is one of the health interventions which are expected to have many health benefits for children. Vitamin A status of children aged six months to five years was shown to be an important predictor of mortality [17, 18]. The effect was significant, especially in populations with low prevalence of clinical signs of Vitamin A deficiency [18]. As Vitamin A was shown to significantly reduce deaths attributed to diarrhea and measles [17, 18], it is natural to expect its effect to be dependent on the prevalence of these causes of mortality. Insignificant association between Vitamin A and under-five mortality was also observed by another study [19].

Promotion of breastfeeding is considered to be a key component of child survival strategies in many developing countries [20]. Accordingly, exclusive breastfeeding during the first six months of life, early initiation of breastfeeding within one hour of birth and continuation of breastfeeding with other complementary foods till 2^nd birth day of the child are recommended [21, 22]. As exclusive breastfeeding is reported to be associated with intermediate causes of under-five mortality, such as diarrhea and respiratory infections [23, 24], its effect on under-five mortality may vary based on the prevalence of these intermediate causes. Besides, the extent of the effect of breastfeeding on child mortality varies across the age category of children, with younger infants deriving the greatest benefit [25]. There are, however, findings which are inconsistent with the above conclusions, showing insignificant association between child mortality and breastfeeding [26]. Besides, problems with breastfeeding, which are proxy indicators of exclusive breastfeeding, were not shown to have significant effect on under-five mortality in Africa [15, 27].

WHO recommends hygiene during delivery, keeping the newborn warm, early initiation of breastfeeding, care of the eyes, care during illness, immunization and care of low-birth-weight newborns as essential newborn care practices [28]. However, majority of deliveries in developing countries in general and in Ethiopia in particular take place at home by untrained birth attendants [1]. As a result, many lifesaving practices are either missed or done inappropriately, contributing to widespread maternal and childhood morbidities and mortalities. The effect of the different interventions recommended during pregnancy and childbirth, however, is expected to be dependent on how they are brought to the users [29].

Other maternal and child characteristics have also been studied and attributed to child and maternal deaths. For example, mothers with short birth intervals may have insufficient time to restore their nutritional reserves, a situation which is thought to adversely affect fetal growth. As a result, WHO recommends at least 24 months of gap between a birth and a subsequent pregnancy [30]. This was also supported by other studies [31, 32]. However, it is argued that, short birth intervals can be a consequence than a cause of child mortality [33], i.e., parents with child loss are more likely to have next child sooner than those with alive child.

It has been reported that, first born children are less likely to die than higher birth order children, possibly as a result of firstborns being favored with vital resources such as food and care [34] and this is supported by other studies [32, 35]. To the contrary, it is argued that first born children are more likely to be born to mothers at younger ages thereby experiencing a higher mortality risk [14]. Insignificant association between child mortality and birth order was reported by another study too [26].

In addition to the inconsistent findings of studies outlined above, the effect of different maternal and child related factors on under-five mortality may vary through time because of changes in the life style of nations. Furthermore, the associations may be context dependent. Mortality studies in the study site have been lacking, as the Arba Minch Demographic Surveillance Site (DSS), which is located at the extreme south of the country, is relatively recently established research center in the area. These are the reasons that call for investigation of determinants in general and maternal and child related factors in particular of under-five mortality in the study area. Therefore, this study investigated maternal and child related predictors of under-five mortality in Gamo Gofa Zone, southern Ethiopia by including data from both DSS and non-DSS kebeles.

Outputs of the study will enhance comprehensive knowledge about determinants of under-five mortality in the country by providing information from those uninvestigated areas with a wider population category. The study tried to identify contextualized and prioritized maternal and child health related areas in order to sustain reduction of under-five mortality and improve child survival during the Sustainable Development Goals (SDGs) era. The determinant factors for this study were framed using Henry Mosley and Lincoln Chen’s analytic framework for the study of determinants of under-five mortality. The adapted conceptual framework for the overall determinants of under-five mortality is presented elsewhere [36].

Methods

Sample size determination

The sample size was calculated using Statcalc command of Epi info 7 statistical software package. The prevalence of exposure (selected determinants) among controls and cases were estimated from previous studies [9, 10, 39–42] or calculated from the data available from Arba Minch DSS’s Database. Then, the sample size required for detecting an odds ratio (OR) with a two-sided probability of type I error of 5% and a power of 80% was determined for main exposure variables with control to case ratio of two. The maximum sample size, which corresponded to home delivery was taken, subsequently. As depicted in Table 1, a minimum of 241 cases and 482 controls were required. By applying a design effect of 1.5 and adding 5% to compensate for non-response, a total of 380 cases and 760 controls were required. The details of the estimations, indicators and sample size required for selected variables are summarized in Table 1.

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Table 1. Variables and their corresponding indicators used for sample size estimation, Gamo Gofa Zone, 2014.

https://doi.org/10.1371/journal.pone.0202124.t001

Results

Data from 381 cases and 762 controls were retrieved giving a response rate of 100% (against the estimated sample). Majority 837(73.2%) of the children were from rural kebeles. Slightly more than half 210(55.1%) of the cases and 382(50.1%) of the controls were males. With regard to maternal education, more than half 210(55.1%) of the cases and less than half 362(47.5%) of the controls had no formal education. Pertaining to ethnic background, majority of mothers of the cases 286(75.1%) and the controls 571(74.9%) were Gamo. Most mothers of the cases 264(69.3%) and controls 539(70.7%) were housewives. Nearly half of husbands of the cases 191(50.1%) and controls 433(56.8%) were farmers. Using wealth index, 124(32.5%) of the cases and 328(43.0%) of the controls were classified as rich. Majority of the cases 262(68.8%) and controls 492(64.6%) were born at home. The details of the socio-demographic characteristics of the study participants were presented elsewhere [36].

Association between personal illness control related factors and under-five mortality

Among factors classified as ‘personal illness control’; post-natal care (PNC) for the index pregnancy/child, antenatal care (ANC) for the index pregnancy, immunization status of the child for his /her age and whether the child had Vitamin A supplementation or not were significantly associated with under-five and/or infant mortality (Table 2).

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Table 2. The association between personal illness control related factors and under-five mortality, Gamo Gofa Zone, 2014.

https://doi.org/10.1371/journal.pone.0202124.t002

The odds of mortality was about two times higher among under-five children who lacked PNC (AOR of 2.27(1.25–4.11)) than those who had. Similarly, lack of PNC service was shown to increase the odds of mortality by about 2 fold during the first year of life of the child (AOR of 2.35(1.02–5.45)). Infants who had at least four ANC follow-up during their pregnancy had less odds of mortality (AOR of 0.45(0.23–0.90)) than those infants who lacked ANC. Though it was not significant, similar effect was observed among under-five children with AOR of 0.72(0.42–1.24) (Table 2).

The odds of mortality among under-five children who were partially immunized for their age, was about four times higher (AOR of 3.62(2.02–6.50)) than those fully immunized. The odds of mortality among under-five children, who were not immunized at all, was about 11 times higher (AOR of 11.02(5.16–23.53)) than children who were fully immunized for their age. Similarly, significant increment of odds of mortality was observed among partially (AOR of 4.10(1.81–9.30)) and not immunized (AOR of 18.54(6.22–55.26)) infants than fully immunized infants (Table 2).

Under-five children who did not have Vitamin A supplementation at least once after six months of their age had about 8 times (AOR of 7.61(4.72–12.26)) higher odds of mortality than those who did. Similarly, lack of Vitamin A supplementation was shown to increase odds of mortality during the first year of age of the child (AOR of 15.29(6.38–36.65)). In this study, place or attendants of delivery of index child were not significantly associated with under-five mortality (Table 2).

Association between child feeding and newborn care practices and under-five mortality

Among factors related with child feeding and newborn care practices, history of ever breastfeeding and timing of first bath of the index child were significantly associated with under-five mortality. Under-five children who were never breastfed had about 8 times (AOR of 8.09(4.08–16.05)) higher rate of odds of mortality than those who were ever breastfed. Similarly, those infants who were never breastfed had higher rate of odds of mortality (AOR of 14.19(5.51–36.50)) than those who were ever breastfed. Delaying first bath of a child, at least, to 24 hours after birth was shown to reduce odds of under-five mortality by 50% (AOR of 0.50(0.34–0.73)) and odds of infant mortality by 54% (AOR of 0.46(0.28–0.77)) than having first bath within 24 hours of birth (Table 3).

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Table 3. The association between child feeding and newborn care practices and under-five mortality, Gamo Gofa Zone, 2014.

https://doi.org/10.1371/journal.pone.0202124.t003

Although the associations were in expected directions, associations between under-five and/or infant mortality and factors like exclusive breastfeeding status of the child, history of bottle feeding, breastfeeding initiation time and history of something applied to the umbilical wound were not statistically significant (Table 3).

Association between other maternal and child related factors and under-five mortality

Among other maternal and child related factors included in model 3 (Table 4); birth interval, history of child death before the index child, type of birth of index child and presence of live birth after index child were significantly associated with under-five and/or infant mortality. Under-five children who had birth interval of 24–36 months (AOR of 0.48(0.28–0.82)) or more than 36 months (AOR of 0.46(0.26–0.79)) had less odds of mortality than those children who had birth interval of less than 24 months. Similarly, infants who had birth interval of 24–36 months (AOR of 0.28 (0.14–0.54)) or more than 36 months (AOR of 0.29 (0.15–0.55)) had less odds of mortality than infants who had birth interval of less than 24 months (Table 4).

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Table 4. The association between maternal and child factors and under-five mortality, Gamo Gofa Zone, 2014.

https://doi.org/10.1371/journal.pone.0202124.t004

Under-five children (AOR of 1.97(1.07–3.61)) and infants (AOR of 3.37 (1.51–7.50)) with history of death of older siblings had higher rate of odds of mortality than those without history of death of older siblings (Table 4).

Those under-five children whose births were multiple had higher rate of odds of mortality (AOR of 13.72(5.26–35.79)) than those who were singleton birth. Similar effect was observed among infants (AOR of 21.18 (5.85–76.74)). Under-five children of mothers with history of birth after the index child had a higher rate of mortality (AOR of 5.06(2.80–9.16)) than those without. However, age of mothers at child birth, gravidity and birth order of index child were not statistically significantly associated with under-five mortality in this study (Table 4).

Discussion

This study identified vital maternal and child health related predictors of under-five mortality by controlling for effects of potential confounders at design and analysis stage. To enhance that, efforts such as matching at design stage and weighted conditional logistic regression during analysis were employed. Lack of post-natal care, immunization status of the child, lack of Vitamin A supplementation, lack of breastfeeding, delaying first bath at least for 24 hours, shorter previous birth interval, history of death of older sibling of the index child, multiple birth and live birth after the index child were determinant factors which were significantly associated with under-five mortality.

However, as the information was collected retrospectively; systematic errors, such as recall bias might have affected some of the responses. Besides, because of the wide confidence interval of the effect sizes of some of the variables, which was attributed to small sample size, findings particularly those related to determinants of infant mortality need to be interpreted cautiously. In controlling confounding factors, the study may not be exhaustive enough to address all confounding factors. However, it is possible to assume that the confounding effect of other proximate variables were at least partially addressed by controlling distal factors, which are assumed to be operating through those proximate factors.

Both mothers and their newborns are vulnerable during the postnatal period and provision of PNC services at this period is expected to prevent maternal and child morbidity and mortality [44, 45]. This time is crucial not only to treat complications arising from the delivery, but also to provide women with important information on how to care for themselves and their children. In support of this, in the current study, lack of PNC was found to increase the odds of mortality by about 2.3 fold during the first five years of age and by about 2.4 fold during the first year of age of the child. This finding is in line with another study [46] which analyzed Demographic and Health Survey data from sub-Saharan African countries. Those findings call for strengthening of provision of PNC as one of the main strategies for under-five mortality reduction during the SDGs era.

Infants whose mothers had at least four ANC follow-up during their pregnancy had less odds of mortality than those infants who lacked ANC. Though it was not significant, similar effect of ANC was observed among under-five children. Similarly despite not being statistically significant, experience of even less than four ANC follow ups during pregnancy of the index child was shown to reduce odds of under-five and infant mortality. Similar protective effect of ANC follow up was observed by other studies [6, 12]. This may be because of the criticality of this time for the mother and the fetus helping to identify high risk pregnancy including multiple pregnancy (which was shown to be a risk factor in this study) in order to take appropriate actions.

In contrast to reports of other previous studies [6, 7] about positive effect of institutional or skilled attendance of delivery on under-five mortality, place and attendance of delivery of the index child were not significantly associated with under-five mortality in the current study. Nevertheless, institutional delivery did not show a protective effect in other studies conduct in Ethiopia [9, 10]. Lack of significant association between delivery at hospital or skilled attendant and neonatal mortality was also reported by another study [47]. This may be due to the fact that complicated cases were more likely to come for institutional delivery than to stay at home. However, health service delivery systems in developing countries are criticized for failing to bring the expected health benefits at expected level, partly because of dysfunctional health services [4, 5]. So, such findings could be motivating factors to question and investigate the quality of delivery services provided by health facilities in the study areas.

Immunization is the most effective child-survival intervention to date and the immunization status of children was reported to be an important factor of survival [7] with its greater impact in communities with low socioeconomic status [16]. Similarly, in the current study, immunization status for age of the child was significantly associated with under-five and infant mortality. The odds of under-five and infant mortality were also high among children who lacked Vitamin A supplementation at least once after six months of age than those who took. Vitamin A supplementation is another child health intervention and reported to reduce under-five mortality attributed to diarrhea and measles [17, 18]. Both the above findings ratify the importance of strengthening of these interventions for sustenance of the reduction of under-five mortality and achieving targets of child health related SDGs.

Among factors related to child feeding and newborn care practices, history of ever breastfeeding was found to be significantly associated with low under-five and infant mortality. Breastfeeding has been reported to be a major determinant of child health and mortality [42, 48]. As a result, the promotion of breastfeeding is considered to be a key component of child survival strategies in many developing countries [20]. Although, owing to the design of this study, problem of residual reverse causality could not be ruled out, the finding of this study support the promotion of breastfeeding as a strategy for better child survival in developing countries like Ethiopia.

In this study, exclusive breastfeeding status of the child and history of bottle feeding were not significantly associated with under-five mortality. This was in line with the finding of another study [49]. Insignificant difference of mortality among exclusively breast fed children and pre-dominantly breast fed children was also reported by another study [48]. Problem of breastfeeding which may be a proxy indicator of lack of exclusive breastfeeding was also not associated with under-five mortality by another study [50]. The lack of significant association in the current study may be because of the rareness of these practices in the study area, as exclusive breastfeeding is not widely practiced, that only 32% of Ethiopian infants 4–5 months were reported to be exclusively breast fed [1].

Delaying first bath of a child at least to 24 hours after birth was shown to reduce odds of under-five and infant mortality. This finding reinforces the WHO recommendation of delaying first bath of a child after 24 hours [51] as one of the strategies for newborn thermal care at delivery.

Among other maternal and child related factors, previous birth interval was significantly associated with both under-five and infant mortality. Children who had longer birth intervals had less odds of mortality than those children who had birth interval of less than 24 months. Studies in developing countries also showed inverse association between the length of preceding birth interval and under-five mortality [9, 31, 32, 52]. This may be because of maternal depletion, as women with short intervals between two pregnancies may have insufficient time to restore their nutritional reserves and may suffer maternal depletion, a situation which is thought to adversely affect fetal growth. The latter is expressed in low birth weight or small size for gestational age [30] which in turn have a negative effect on child survival [47]. Competition for resources among the siblings may be another explanation for the association. Therefore, this finding strengthens the importance of adhering to WHO recommendation of at least 24 months birth spacing [30] through promotion of family planning services, specially uptake of post-partum family planning methods.

In this study, history of death of older siblings of the index child was shown to significantly increase the odds of mortality among under-five children and infants. Similarly, higher risk of under-five mortality was reported among children who had death of an older sibling by other studies [52–55]. This may be because of the fact that, factors responsible for the death of previous child sustain and result in the death of the index child. Therefore, reduction of under-five mortality may have twofold advantages as child death is shown to be associated with maternal mental distress[56–58], which in turn is shown to have effect on child wellbeing and survival [59, 60].

Although multiple births are relatively rare events compared to singleton births, they are reported to be a risk factor for under-five mortality, particularly in resource limited settings [52, 61–63]. In the current study, those under-five children, including infants, whose births were multiple had higher rate of odds of mortality than those who were singleton births. So, these findings indicate the importance of meticulous identification and investigation of high risk pregnancies, including multiple pregnancies, during prenatal period in order to take appropriate action.

History of live birth after the index child was examined only for under-five children in order to account for the time required to give birth after birth of the index child. And it was significantly associated with under-five mortality that, under-five children of mothers with history of birth after the index child had higher rate of odds of mortality than those without. This may be because of resource competition for feeding and care. However, birth after index child may be as a consequence of an intention to replace the dead child rather than it being a cause of child mortality. This calls for further investigation with researches that employ stronger study designs.

Finally, even though the two districts for this study were selected purposively, we assumed that the Arba Minch Zuria District and Arba Minch Town are appropriate to represent the population of the Zone. Owing to the study included kebeles from urban-rural, from DSS-non-DSS and from different agro-ecological and climatic conditions; the findings of this study can be generalized to other areas of the country, especially to communities with similar context.

Conclusions

Among factors classified as ‘personal illness control’, having at least four ANC follow-up visits during pregnancy, utilization of PNC, immunization status of the child and supplementation of Vitamin A for eligible children were significantly associated with under-five mortality. Therefore, these interventions should be strengthened and sustained as strategies of child survival interventions during the SDGs era to maintain reduction of under-five deaths.

Similar to other studies conducted in the country, the current study showed insignificant association between child hood mortality and place and attendants of delivery. So, these findings may trigger a question on the quality of delivery services being provided by health facilities in the study area for further investigation in order to extract the expected positive effects of those health services.

As delaying first bath of a child at least to 24 hours after birth was shown to reduce odds of under-five mortality, its advocacy and strengthening it as one of the strategies of a newborn thermal care at delivery is crucial.

Previous birth interval was among maternal and child factors significantly associated with under-five mortality. Besides, birth after index child was shown to increase odds of mortality among under-five children. So, advocacy of family planning in general and post-partum family planning in particular to delay inter-birth intervals at least to 24 months may be crucial not only for the subsequent birth, but also for the older children.

Children who were from multiple births had higher rate of odds of mortality than those who were singletons. Meticulous identification and investigation of high risk pregnancies, including multiple pregnancies, during prenatal period in order to minimize the negative effect of such risk factors is important.

Supporting information

Acknowledgments

We are grateful to the Arba Minch University and Addis Ababa University, School of Public Health for their financial support. We are also grateful to: the Gamo Gofa Zone Health Department, Arba Minch Zuria District and Arba Minch Town Health Offices and Officials of all the kebeles for their cooperation in writing support letters to concerned bodies. We also thank the Arba Minch DSS Coordinating Office for providing us the required data. We would like to thank Mr. Aman Yesuf, Mss. Mekdes Kondale, Mr. Biniyam Bogale and Dr. Rahmeto Negash for their assistance in data collection process and during financial settlement in the Arba Minch University. We are also grateful to Mr. Leul Birhanu for his critical review of the manuscript. Finally, we thank data collectors and all study participants.