This study focuses on the neonatal effects of exposure to household air pollution from cook stoves. Working with local Guatemalan partners and the University of California Berkeley, we will collect personal exposures to household air pollutants from solid fuels (primarily wood) among a cohort of pregnant Guatemalan women and their infants. The study will build local technical capacity among health workers to collect standardized, valid measures of infant anthropometry (weight, length and head circumference) and neurodevelopment in the first year of life. Neurodevelopment will be assessed using a standardized instrument that will be locally validated for infants born at home in a resource-poor setting. In January 2012 we will enroll 30 women and conduct a feasibility study of a randomized controlled trial of a clean stove intervention. These pilot data will support a future R01 application with the overarching goal to conduct the first randomized control trial to compare the effects of in utero and infant exposures to household air pollutants (HAP) on infant’s anthropometry and neurodevelopment in the first year of life.