example, see Smith and Haddad 2015; Headey 2013; Ruel, Alderman, and the Maternal and Child Nutrition Study Group 2013; Heltberg 2009). Ruel et al. (2013) find that the underweight rate is more sensitive to economic growth than the stunting rate. The estimated effect of economic growth on child undernutrition captures both the direct effect, through household resources, and the indirect effect, through the expansion and improvement of physical and economic infrastructure and social services.

Using statistics from the World Bank’s World Development Indicators (WDI) database, we estimate the elasticity of national stunting rates with respect to real Gross National Income (GNI) per capita for Pakistan and other South Asian countries (Bangladesh, Bhutan, India, Nepal, Sri Lanka).<sup>23</sup> We do this for the period from 1990 to 2015, and the recent subperiod from 2000 to 2015. For Pakistan, we have child undernutrition statistics for four years in the full period, and for three years in the subperiod. A 10% increase in real GNI per capita in Pakistan is associated with a 2.3% decline in the stunting rate over the full period. This elasticity estimate places the country on the low end of the range of estimates from cross-country regressions. In the more recent subperiod, when Pakistan experienced an increase in the stunting rate, the national income elasticity of stunting is positive. In comparison, for other South Asian countries, a 10% increase in national income is associated with a 2.5% to 10.4% decline in the stunting rate, depending on the country and the period.

We also estimate the elasticity of undernutrition rates to the consumption-based poverty rate measured by the $1.90/day/person poverty line for Pakistan, and other South Asian countries (Bangladesh, India, and Sri Lanka), for the period from 2000 to 2015.<sup>24</sup> We do not look at a longer period because of concerns about the reliability of poverty statistics for Pakistan before the 2000s (World Bank 2016a). For all countries, if needed, we linearly interpolate poverty rates to the years with undernutrition statistics. For Pakistan, while the stunting rate increased over the period, the poverty rate declined substantially from 64% in 2001 to 30% in 2013. Given this, the poverty elasticity of stunting for the country is negative. In contrast, for other South Asian countries, a 10% decline in the poverty rate is associated with a 1.5% to 7.8% decline in the stunting rate, depending on the country.

To the best of our knowledge, studies investigating the evolution (or lack thereof) in nutrition outcomes for Pakistan are absent, with the exception of Headey, Hoddinott, and Park (2016). These authors decompose the gain in average HAZ into the contributions from various factors in four South Asian countries, including Pakistan from 1990–91 to 2012–13, using DHS rounds (they estimate that average HAZ improved by 16% in Pakistan over this period), limiting the factors that they examine to a small common set across the countries.<sup>25</sup> The study finds that the gain in average HAZ for Pakistan is mainly due to gains in household wealth and the use of health services (specifically, institutional births and antenatal visits), followed by gains in the education attainment of both mothers and fathers, and declines in household fertility and in area-level open

> 23 We estimate an elasticity for each country by regressing the given undernutrition rate on per-capita national income under a log-log specification.

> 24 We estimate an elasticity for each country by regressing the given undernutrition rate on the poverty rate under a log-log specification.

> 25 The factors that Headey, Hoddinott, and Park (2016) examine comprise of household wealth, parental education, use of formal maternal and child health services, water and sanitation, and fertility.

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