Assessing the Impact of Birth Spacing on Child Health Trajectories Ray Miller Harvard Center for Population and Development Studies hrmiller@hsph.harvard.edu Mahesh Karra Boston University mvkarra@bu.edu September 29, 2017 Abstract We investigate the effect of birth spacing between siblings on child health tra- jectories and investments using longitudinal data from the Young Lives Study. We analyze a birth cohort of 8,000 children with data collected between 2002 and 2013 from four low-and middle-income countries. We find increased height among children who are more widely spaced relative to children who are narrowly spaced (within two years from an older sibling). However, we also find evidence of compensatory growth (converging height and HAZ scores) for closely spaced children as they age. There is a positive association between birth spacing and prenatal investments, which suggeests that the emergence of height gaps could be driven by parental behavior in addition to biological factors. However, we find little evidence that compensatory growth is driven by remedial health in- vestments in closely spaced children after birth, suggesting catch-up growth as a biological phenomenon. Available data suggests financial constraints and care- giver perceptions of child health as possible explanations for lack of remedial investments. JEL classifications: I10, O57 Keywords: birth spacing, health, nutrition, child investments, compensatory growth 1
1 Introduction The importance of birth spacing for maternal and child health has been a long-standing source of interest to researchers and policymakers alike (World Health Organization, 2005). Evidence from systematic reviews and other empirical studies have suggested that short birth intervals (less than two years between births) may be associated with increased risk of maternal and child morbidity, including pregnancy-related complica- tions (high blood pressure, pre-eclampsia), preterm birth, low birthweight, and small for gestational age, as well as increased risk of mortality for both women and children (Conde-Agudelo et al., 2006; DaVanzo et al., 2004; Winikoff, 1983). Some studies have also examined the relationship between birth spacing and longer-term cognitive and educational outcomes in children and have found longer intrapartum spacing to be associated with improved school test scores in older siblings, while the effects of longer spacing were found to be minimal for younger siblings (Broman et al., 1975; Buckles and Munnich, 2012). By the same token, studies have also begun to explore the role of birth order on child health and socioemotional development and have found that older siblings are likely to be more socially outgoing and persistent than their younger siblings (Black et al., 2016). When pooling the evidence together, however, results from this body of research have concluded that many of the findings on both birth spacing and birth order, par- ticularly those related to child morbidity and adverse health outcomes, are either weak or mixed (Dewey and Cohen, 2007). Moreover, to our knowledge, no studies have in- vestigated whether adverse health outcomes associated with short intrapartum spacing persist in older children, especially as they transition into adolescence. In this study, we investigate the effect of birth spacing between siblings on child health outcomes (height and weight) using longitudinal data that was collected on a cohort of children and their sibling in four low-and middle-income countries. As part of our analysis, we assess the impact of short and long birth intervals for the pooled sample of children and separately by country, and we also assess whether and how this estimated impact changes for the sample as children aged. 2 Background The relationship between short birth intervals and high infant and child mortality has been well established in a wide range of populations (DaVanzo et al., 2004). On the other hand, there is very little empirical evidence that directly assesses the links between birth intervals and child morbidity, which is surprising considering the mech- anisms through which birth intervals may operate to influence child health and well- being have been extensively discussed in the literature (DaVanzo et al., 1983; Miller, 1991). In particular, the consequences of a short birth interval for child health out- comes, particularly at younger ages, have often been attributed to the physiological effects related to the “maternal depletion syndrome,” which postulates that the woman 2
may not have fully recuperated from one pregnancy before supporting the next one (Conde-Agudelo et al., 2012; Dewey and Cohen, 2007). Other mechanisms that have been hypothesized to contribute to a detrimental effect of a short preceding interval include: 1) behavioral effects that are associated with competition between siblings, which may include competition for parental time or resources; 2) depleted parental investments or household resources that were used for the earlier birth, which may include a lack of physical resources or even a psychological or emotional inability to provide the later child with adequate attention if its birth came sooner than desired; and 3) larger morbidities through higher disease transmission among closely spaced siblings, particularly at younger ages (DaVanzo et al., 2004; Conde-Agudelo et al., 2012). Several recent studies have examined the extent to which birth order may contribute to child height and weight, nutritional status, and other measures of child development and attribute differences in health outcomes between siblings to sibling competition, gender bias (son preference), and resource constraints (Jayachandran and Pande, 2015; Black et al., 2016; Nuttall and Nuttall, 1979). However, none of these studies directly estimate the extent to which birth intervals play a role and, in the best of analyses, only control for birth interval effects by examining the effects of birth order among populations in which siblings are similarly spaced. The closest approximation of po- tential child morbidity effects from birth spacing is provided by studies that examine the relationship between indicators of childhood malnutrition (stunting, wasting, un- derweight) and family formation patterns, but evidence of the effect from this literature was found to be mixed (Winikoff, 1983). A more recent systematic review by Dewey and Cohen (2007) assessed the evidence on the effects of birth spacing on child nutri- tional status from 52 studies and noted that approximately half (25) of these studies found that a previous birth interval of at least 36 months was associated with a 10 to 50 percent reduction in childhood stunting (with similar findings for wasting), whereas the remaining studies either found no association or were inconclusive. A study by Rutstein (2008), which pooled birth history data from 52 Demographic and Health Surveys (DHS) that were conducted from 2000 to 2005, observed a positive association between birth interval length and child nutritional status outcomes. Similarly, a more recent study by Fink et al. (2014), which pooled 153 cross-sectional DHS surveys across 61 countries conducted between 1990 and 2011, found that birth intervals of less than 12 months and between 12 and 23 months were associated with higher relative risks for stunting (relative risks of 1.09 and 1.06, respectively) as compared to a 24–35 month inter-pregnancy interval. Due to the cross-sectional nature of the data, however, both the Rutstein (2008) and the Fink et al. (2014) studies were limited in their ability to make inferences on the persistence of these associations in children over time. Our study aims to address the methodological shortcomings in the literature in two ways. Firstly, we improve on prior methodologies that have almost exclusively relied on cross-sectional data by exploiting a longitudinal dataset that allows us to effectively observe trends of the estimated birth spacing effect across cohorts and over time. Secondly, we employ a secondary statistical model that relies on within-family 3
Recommend
More recommend
