This paper studies how in utero exposure to a large-scale climate adaptation program affects birth out
comes. The program built around one million cisterns in Brazil’s poorest and driest region to promote
small-scale decentralized rainfall harvesting. Access to cisterns during early pregnancy increased birth
weight, particularly for more educated mothers. Data suggest that more educated women complied more
with the program’s water disinfection training, highlighting that even simple, low-cost technologies
require final users’ compliance (‘‘the last mile”) to be effective. In the context of growing water scarcity,
adaptation policies can foster neonatal health and thus have positive long-run implications.
This paper studies how in utero exposure to a large-scale climate adaptation program affects birth out
comes. The program built around one million cisterns in Brazil’s poorest and driest region to promote
small-scale decentralized rainfall harvesting. Access to cisterns during early pregnancy increased birth
weight, particularly for more educated mothers. Data suggest that more educated women complied more
with the program’s water disinfection training, highlighting that even simple, low-cost technologies
require final users’ compliance (‘‘the last mile”) to be effective. In the context of growing water scarcity,
adaptation policies can foster neonatal health and thus have positive long-run implications.
