Measuring under-5 mortality and fertility through mobile phone surveys: an assessment of selection bias in 34 low-income and middle-income countries.

OBJECTIVES: This study aims to assess sample selection bias in mobile phone survey estimates of fertility and under-5 mortality. DESIGN: With data from the Demographic and Health Surveys, we use logistic regressions to identify sociodemographic correlates of mobile phone ownership and access, and Poisson regressions to estimate the association between mobile phone ownership (or access) and fertility and under-5 mortality estimates. We evaluate the potential reasons why estimates by mobile phone ownership differ using a set of behavioural characteristics. SETTING: 34 low-income and middle-income countries, mostly in sub-Saharan Africa. PARTICIPANTS: 534 536 women between the ages of 15 and 49. OUTCOME MEASURES: Under-5 mortality rate (U5MR) and total fertility rate (TFR). RESULTS: Mobile phone ownership ranges from 23.6% in Burundi to 96.7% in Armenia. The median TFR ratio and U5MR ratio between the non-owners and the owners of a mobile phone are 1.48 and 1.29, respectively. Fertility and mortality rates would be biased downwards if estimates are only based on women who own or have access to mobile phones. Estimates of U5MR can be adjusted through poststratification using age, educational level, area of residence, wealth and marital status as weights. However, estimates of TFR remain biased even after adjusting for these covariates. This difference is associated with behavioural factors (eg, contraceptive use) that are not captured by the poststratification variables, but for which there are also differences between mobile phone owners and non-owners. CONCLUSIONS: Mobile phone surveys need to collect data on sociodemographic background characteristics to be able to weight and adjust mortality estimates ex post facto. Fertility estimates from mobile phone surveys will be biased unless further research uncovers the mechanisms driving the bias.

Dynamic household structure and composition: a manual for longitudinal analysis of living arrangements.

OBJECTIVE: This research note introduces a set of tools to conduct analysis of household structure and composition with either limited or comprehensive longitudinal data. The data used here are from Health and Demographic Surveillance Systems in Africa, but the methods can be adapted and applied to other longitudinal micro-data such as register data. A training manual describing the procedures for creating time-varying household measures step-by-step is supplied as supplementary material to this note. Code is provided in STATA but can easily be translated for other statistical software, and the logic for each step remains the same. RESULTS: The analysis of household structure demonstrates how with limited data (such as a household identifier), it is possible to construct time-varying measures of household membership, including household size or the number of members in specific age and sex groups. The analysis of household composition demonstrates how with expanded data (including links to parents in addition to residence status in the same household), it is possible to construct time-varying measures of household membership of specific kin, i.e. mother, sibling or grandparent. The results illustrated in this research note are a taste of what can be achieved by following the training manual in the supplementary material.

Age-specific sex ratios: Examining rural-urban variation within low- and middle-income countries.

The balance of men and women in society, captured by sex ratios, determines key social and demographic phenomena. Previous research has explored sex ratios mainly at birth and up to age five at national level, whereas we address rural-urban gaps in sex ratios for all ages. Our measures are based on the United Nations data on rural and urban populations by age and sex for 112 low- and middle-income countries in 2015. We show that rural sex ratios are higher than urban sex ratios among children and older people, whereas at working ages, urban areas are dominated by males. Our analysis suggests that the urban transition itself is not driving the gap in rural-urban sex ratios. Rather, internal migration seems to be key in shaping rural-urban sex ratio divergence in sub-Saharan Africa, while both internal migration and mortality differentials appear to be the predominant mechanisms driving sex ratio gaps in Latin America.

An evaluation of truncated birth histories for the rapid measurement of fertility and child survival.

BACKGROUND: Full birth histories (FBHs) are a key tool for estimating fertility and child mortality in low- and middle-income countries, but they are lengthy to collect. This is not desirable, especially for rapid turnaround surveys that ought to be short (e.g., mobile phone surveys). To reduce the length of the interview, some surveys resort to truncated birth histories (TBHs), where questions are asked only on recent births. METHODS: We used 32 Malaria Indicator Surveys that included TBHs from 18 countries in sub-Saharan Africa. Each set of TBHs was paired and compared to an overlapping set of FBHs (typically from a standard Demographic and Health Survey). We conducted a variety of data checks, including a comparison of the proportion of children reported in the reference period and a comparison of the fertility and mortality estimates. RESULTS: Fertility and mortality estimates from TBHs are lower than those based on FBHs. These differences are driven by the omission of events and the displacement of births backward and out of the reference period. CONCLUSIONS: TBHs are prone to misreporting errors that will bias both fertility and mortality estimates. While we find a few significant associations between outcomes measured and interviewer's characteristics, data quality markers correlate more consistently with respondent attributes, suggesting that truncation creates confusion among mothers being interviewed. Rigorous data quality checks should be put in place when collecting data through this instrument in future surveys.

Male Fertility and Internal Migration in Rural and Urban Sub-Saharan Africa.

Subnational differences in male fertility within sub-Saharan African countries have not been explored, nor the differences in male fertility according to migration status been sufficiently probed. We study divergences in rural and urban male fertility and investigate the relationship between male fertility and migration across 30 sub-Saharan African countries. We employ 67 Demographic and Health Surveys to estimate completed cohort fertility among men aged 50-64 according to migration status. Overall, we find that urban male fertility has declined faster than rural male fertility, widening the gap between the sectors. Rural-urban migrant men have lower fertility than their rural non-migrant counterparts. Men migrating within the rural sector have similarly high fertility as rural non-migrants, while urban-urban migrant men have even lower fertility than non-migrant urban men. Using country-fixed effects models, we find that among men with at least secondary education, differences in completed cohort fertility by migration status are widest. When we consider the timing of migration in relation to the timing of the birth of the last child, we observe that migrant men are a select group, having around two children less than non-migrant rural men. There is also evidence of adaptation to destination, though to a lesser extent. Furthermore, migration within the rural sector does not seem to be disruptive to fathering. These results indicate that rural-to-urban migration has the potential to delay rural fertility decline, and that urban male fertility is likely to decline further, especially as the proportion of urban-to-urban migration increases.

The shifting rural-urban gap in mortality over the life course in low- and middle-income countries.

Studies have shown that children in rural areas face excess risks of dying, but the little research on spatial inequalities in adult mortality has reached mixed conclusions. We examine rural-urban differences in mortality in 53 low- and middle-income countries. We consider how the rural-urban mortality gap evolves from birth to age 60 by estimating mortality based on birth and sibling histories from 138 Demographic and Health Surveys run between 1992 and 2018. We observe excess rural mortality until age 15, finding the largest differences between urban and rural sectors among 1-59-month-olds. While we cannot claim higher mortality among urban adults than those in rural areas, we find a reduced gap between the sectors over the life course and a diminishing urban advantage in adult mortality with age. This shift over the life course reflects a divergence in the epidemiologic transition between the rural and urban sectors.

The Crucial Role of Mothers and Siblings in Child Survival: Evidence From 29 Health and Demographic Surveillance Systems in Sub-Saharan Africa.

A considerable body of research has studied the effects of siblings on child mortality through birth intervals. This research has commonly focused on older siblings. We argue that birth intervals with younger siblings may have equal or stronger effects on child mortality, even during a mother's pregnancy. Moreover, we contend that birth interval effects need to be considered only when siblings are coresident. Using longitudinal data from 29 Health and Demographic Surveillance Systems across sub-Saharan Africa, covering more than 560,000 children, we examine the proximate role of siblings and mothers in child mortality. We find that a birth interval of 24 months or more is advantageous for both older and younger siblings. The effect of a younger sibling on child mortality is more pronounced than that of an older sibling and adds to the effect of an older sibling. Moreover, child mortality is particularly low during a mother's subsequent pregnancy, contrasting the shock resulting from a younger sibling's birth. Further, we find that a mother's or sibling's absence from the household results in a higher risk of mortality, and the death of either reduces child survival up to six months before the death.

Migrant health penalty: evidence of higher mortality risk among internal migrants in sub-Saharan Africa.

Background: Despite the greater attention given to international migration, internal migration accounts for the majority of movements globally. However, research on the effects of internal migration on health is limited, with this relationship examined predominantly in urban settings among working-age adults, neglecting rural populations and younger and older ages.Objectives: Using longitudinal data from 29 mostly rural sub-Saharan African Health and Demographic Surveillance Systems (HDSS), this study aims to explore life-course differences in mortality according to migration status and duration of residence.MethodsCox proportional hazards models are employed to analyse the relationship between migration and mortality in the 29 HDSS areas. The analytical sample includes 3 836,173 people and the analysis spans 25 years, from 1990 to 2015. We examine the risk of death by sex across five broad age groups (from ages 1 to 80), and consider recent and past in- and return migrants.Results: In-migrants have a higher risk of mortality compared to permanent rural residents, with return migrants at greater risk than in-migrants across all age-groups. Female migrants have lower survival chances than males, with greater variability by age. Risk of dying is highest among recent return migrant females aged 30-59: 1.86 (95% CI 1.69-2.06) times that of permanent residents. Only among males aged 15-29 who move to urban areas is there evidence of a 'healthy migrant' effect (HR = 0.62, 95% CI 0.51-0.77). There is clear evidence of an adaptation effect across all ages, with the risk of mortality reducing with duration following migration.Conclusions: Findings suggest that adult internal migrants, particularly females, suffer greater health disadvantages associated with migration. Policy makers should focus on improving migrant's interface with health services, and support the development of health education and promotion interventions to create awareness of localised health risks for migrants.