1. Conahcyt, CIESAS Pacífico Sur, Oaxaca, Mexico
2. Conahcyt, CIESAS Sureste, San Cristóbal de las Casas, Mexico
3. Health Research Coordination, Mexican Institute of Social Security (IMSS), Oaxaca, Mexico
4. Universidad Autónoma Benito Juárez de Oaxaca (UABJO), Oaxaca, Mexico