vii In about one-fifth of cases, the migrant is a parent (nearly always the father) of the young child; more often the migrant is an uncle or grandparent.

viii In the years leading up to 2008, migration from the region to Mexico was becoming relatively less important. For example, based on our definition, 20 percent of all sampled households in 2008 had a migrant to the United States, but only 11 percent had a migrant to Mexico (half of whom also had another migrant to the United States). We focus on migration to the United States, where the shock first emanated, but consider the role of migration to Mexico in Section 4.4.1.

ix It also includes about ten households (depending on the sample) where no single individual was away for three years, but the combination of migration events for different individuals spanned at least three years.

x As household member migration can change over time, it is possible, but rare, for different children within the same household to have had different exposures to migration as we define it. Five percent of children under six years old were categorized differently from a sibling in 2008 and 9 percent in 2012. In section 4.4.1, we consider alternative definitions for migration exposure to assess sensitivity.

xi Over 2002–08, there were no substantial deviations or shocks in Gross National Income (GNI) or consumer price inflation (CPI), with GNI averaging 4 percent and CPI about 8 percent. Both fell substantially in 2009, after which they slowly recovered to pre-crisis levels (World Bank 2021).

xii This is in contrast to other possible crises, for example, country-specific currency crises with dramatic relative price changes such as in Indonesia (Frankenberg et al. 2003) or the Philippines (Yang 2008), where specific subsets of households benefited.

xiii As migration can have wide-ranging influences on households, without prior information we are unable to comprehensively assess common trends for migrant compared to non-migrant households, including for child anthropometric outcomes. One piece of evidence that is available, however, comes from subjective poverty questions asked in 2008, in which households were asked to place themselves on a six-step poverty ladder in 2008 and in the prior year. Both migrant and non-migrant households reported slight improvements, with 3 percent fewer households on the lowest two steps in 2008 compared to 2007, but no difference (0.2 percentage points) between migrant and non-migrant households.

xiv Other nonexperimental research provides evidence that catch-up growth at later ages (particularly in adolescence) is also possible (Foster 1995; Mani 2012; Prentice et al. 2013). The findings in Bevis and Villa (2020) contrast here as well, suggesting impacts of maternal health extending into adolescence. Since we examine children under six years old in 2008 (and thus under 10 in 2012), patterns of potential later adolescent catch-up would not influence the findings but could lead to modified conclusions in the longer term.

xv Children three years old or older in 2008 would be seven years old or older in 2012. While we measure children seven years old and older in 2012, we do not observe that age group in 2008, so cannot carry out a similar triple difference specification for the cross-sectional cohort analyses. All children 4–7 years old in 2012 were exposed to the shock in early childhood.

xvi As the child anthropometric analyses are reduced form and the variables examined in this assessment are potentially directly influenced by the shock, we do not directly condition on them in the models.

xvii We categorized households as food secure based on the Household Food Insecurity Access Scale (HFIAS), consisting of nine items and four frequency responses, using a 30-day recall period with reference to children under age six in the household (Coates et al. 2007). The widely used and validated scale was developed to reflect three universal domains of the experience of inadequate household-level food access: (1) anxiety about household food supply, (2) insufficient quality, which includes variety and preferences, and (3) insufficient quantity of food supply, the amount consumed, and the physical consequences of insufficiency.

xviii This subsection draws from Saenz de Tejada (2009).

xix This is particularly relevant in the period just after migration, to pay off debt incurred to undertake the journey (usually about $5,000), taking a year or more and likely an inflexible portion of household spending.

xx The left-side panels of Figures 2 and 3a differ slightly, as the latter is based only on the balanced panel sample of children.

xxi Controlling for age, however, the difference in 2008 is 0.30 (P-value=0.035).