status is predictive of the magnitude of height deficit in Indonesian children two to three years after the tsunami. In fact, in a related study (Frankenberg et al. 2013), the authors report a counterintuitive result that the negative effect of the tsunami is stronger for Indonesian children from richer households (i.e., those with pre-tsunami household consumption per capita above the median).<sup>7</sup> Other findings of differential effects discussed in the following section also lend support to the income pathway. These findings include differential effects by availability of irrigation facilities (Ahmed 2016) and social welfare and humanitarian aid programs (Ahmed 2015; Yamano et al. 2005). In a similar fashion, Tiwari et al. (2013) do not find that source of drinking water and access to health facilities moderate the effect of rainfall shocks on child nutrition status in Nepal. Affirmative evidence would have provided support for the importance of the disease environment pathway.

# **VI. Differential effects by shock exposure period**

The effect of shocks and their persistence could depend on the timing of exposure in the child’s life. While it is generally agreed that the first 1,000 days of a child’s life are critical for long-term development (Victora et al. 2008), it is less clear what particular age window is linked with the greatest vulnerability to shocks.

Several of the studies reviewed here focus on a particular period of exposure to a shock (prepregnancy; in utero; first, second, and third trimesters; first, second, and third year after birth). Moreover, a subset of these studies estimates the effect of shocks in more than one period of exposure. We rely on patterns in the estimates of effects from these studies to discuss the relative importance of these age windows. We also discuss which period of exposure has more consistent evidence of persistent effects. For this, we rely on the five studies that examine the effect of early life shocks on adult height.

There is fairly consistent evidence that shocks experienced in the first and second year of life affect child nutrition status and that this effect is persistent (see table 6 for a summary of the evidence). The evidence is less convincing for exposure in the child’s third year of life. For the effect of exposure to a shock in the first year of life, 17 of the 26 estimates gathered from the studies (or 65 percent) are statistically significant. Besides, shocks that hit in these periods of life appear to have persistent effects as illustrated by four of the six estimates of the effect on adult height. Of the 14 estimates gathered from the studies of the effect of exposure to a shock in the second year of life, 11 (79 percent) are statistically significant. In contrast, evidence is relatively weak for the effect of exposure to a shock in the third year of life. None of the four estimates on child HAZ and only one of the five estimates on adult height is statistically significant.

The evidence on the effect of exposure to a shock while in utero is not as compelling as for the first two years after birth, particularly in terms of persistent effects. Overall, 10 of the 19 estimates gathered from the studies for exposure to a shock while in utero suggest adverse effects. None of the five estimates of the effects on adult height is statistically significant while all four estimates

> 7 Measurement error in consumption data could be behind this.

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