Research

Extreme temperatures during pregnancy and adverse birth outcomes: Evidence from 2007 to 2019 Brazilian national birth data

This research provides the first estimates of the impacts of prenatal exposure to extreme temperatures on infant health at birth in a developing country by using the latest national birth data from 2007 to 2019 from all Brazilian municipalities. The identification strategy relies on the use of year and monthly-by-municipality fixed effects which control for any effect associated with climatic or socioeconomic conditions typical of specific months of the year in a given municipality. So recurrent level effects – possibly associated with wet and dry seasons, harvests, availability of food, etc. – are all washed away in the municipality-by-month fixed-effects. I find that an additional day with mean temperature greater than 29 C increases preterm births and low birthweight. Not surprisingly, the adverse effects are borne disproportionately less educated mothers, suggesting that the projected increase in extreme temperatures may further exacerbate the existing birth health disparities across different SES groups. This paper also contributes by investigating the impact of deviations from the normal weather pattern, to identify the extreme weather events after accounting for the adaptation response. I find that prenatal exposure to extreme heat two standard deviations above the municipalities historic average induces preterm births. These results are timely and policy relevant, considering the recent weather trends with rising temperatures and frequent extreme weather events and the lack of evidence on LMICs. 

EU Regulations to Fight Nutrient Surpluses: the Case of Nitrate Vulnerable Zones

Co-authors:  Santiago Guerrero

Nutrient balance indicators can act as a signal for the potential environmental impact of agriculture on water and air. This article estimates the impact of the designation of nitrate vulnerable zones (NVZ) in the European Union (EU), the most comprehensive regulation for curbing water pollution caused by nitrates from agricultural sources in the EU mandated by the Nitrates Directive. Using the OECD agri-environmental indicators database on nutrient balances covering 47 countries and a set of policy variables constructed from EU official documents, we leverage the timing of NVZ designation across EU countries to identify sharp sustained reductions of 12%–18% in Nitrogen pollution, and 20%-25% in Phosphorus. Nonetheless, such reductions are only observed in countries that implemented the Nitrogen Vulnerable Zones in the whole territory as opposed to countries who implemented them partially. The impacts of the NVZ policy are mainly explained by reductions in fertilizer use. The results are robust to numerous robustness checks. They suggest a successful policy tool for tackling Nutrient surpluses.

More than just friends: heterogeneous peer effects in health habits 

This article explores peer effect heterogeneity in adolescent adjusted Body Mass Index (BMI), physical activity and fast food consumption. In particular, this paper makes an original contribution by studying heterogeneous peer effects based on friendship intensity. Adolescents are assumed to interact through a social network, where they have strong and weak friendships. To identify both types, I use Add-Health's wave II friendship roster questionnaire to calculate a friendship score for every friend listed by each student in the sample: friends with a high score are classified into the strong friendship network and the rest into the weak friendship network. We expect strong friendships to have a greater effect on individuals' observed health outcomes. I use a 2SLS strategy to estimate the econometric model, which exploits the network structure as an exogenous source of variation to identify the causal effect of peers choices on individual outcomes. Results provide evidence that supports the heterogeneous peer effect hypothesis: only strong peers have a significant impact on adjusted body weight, physical activity and diet choices. I conduct three different robustness tests: 1) using different threshold levels of the friendship score to define the strong and weak friendship networks; 2) including romantic partners; and 3) studying long-run peer effects (e.g. the effect of peers during wave II on outcomes in wave IV). The robustness tests offer a similar insight to the main results.

The Causal Effect of Physical Activity on Health  in Early Adulthood: A Gene By Environment Instrumental Variables Approach. 

Co-author: Lise Rochaix

This article explores the effect of Physical Activity (PA) on subjective health status and non-communicable diseases (NCDs) during early adulthood. In particular, it analyzes the respective impacts of leisure time physical activity (LTPA) and heavy work-related physical activity (WTPA). To deal with a potential endogeneity bias, we combine an instrumental variables approach. We instrument LTPA by using the Physical activity polygenic score and heavy WRPA by using the academic performance polygenic score . Results suggest that LTPA has a significantly positive effect on the number of NCDs and self-reported health status. WRPA has the opposite effect: it decreases subjective health status and increases the number of NCDs. Lastly, we explore potential heterogeneities between LTPA and WRPA, and we find that only sedentary workers experience a positive effect on health by increasing their LTPA. 

Eating like an American: Impact of Free Trade Agreements on Unhealthy and Healthy Food Imports in the Americas. (2020)

 This paper investigates the impact of FTAs with the US on unhealthy and healthy food imports in the Americas by analyzing a rich dataset of bilateral exchange from the MIT Observatory of Economic Complexity. The identification strategy relies on a Difference-in-Differences estimation. The results show that FTAs play a substantial role in reshaping the food environment of a domestic country. Depending on the region, the DiD estimates range from  $16 to $75 USD increase in per capita unhealthy food imports after implementing an FTA with the US. I also find evidence that FTAs increase the availability of healthy food, though to a lesser extent ($13 to $54 per capita). This suggests that FTAs disproportionately contributed to increasing imports of foods with poor nutritional content in the Americas. In order to relax the parallel trends assumption and provide robustness checks, I employ an augmented synthetic control method (ASCM)  for the CAFTA and NAFTA regions. I then extend the SCM to consider all countries in the Americas that signed an FTA with the USA within a staggered adoption context. The SCM results support DiD findings.  In contrast to previous research, which are single country studies that have focused on either Canada or Mexico and only analyze sugar categories, this paper provides three original contributions. First, I analyze both types of food imports: healthy and unhealthy. Second, this research considers all countries in the Americas that have signed FTAs with the US and not just a subset. Lastly, I use two novel synthetic control methodologies that correct for poor pre-treatment fit and which are flexible to the staggered adoption setting.