[1] Inst Nacl Salud Publ, Ctr Invest Salud Poblac, Direcc Salud Reprod, 7a Cerrada Fray Pedro de Gante 50,Col Secc 16, Mexico City 14080, DF, Mexico
[2] Inst Nacl Salud Publ, Direcc Salud Reprod, Conacyt, Mexico City, DF, Mexico
[3] Inst Nacl Rehabil, Mexico City, DF, Mexico
[4] Inst Nacl Salud Publ, Ctr Encuestas, Mexico City, DF, Mexico
[5] Univ Autonoma Metropolitana, Dept Prod Econ, Campus Xochimilco, Mexico City, DF, Mexico
[6] Inst Nacl Salud Publ, Ctr Invest Salud Poblac, Direcc Salud Reprod, Mexico City, DF, Mexico
[7] Inst Nacl Salud Publ, Ctr Invest Salud Poblac, Mexico City, DF, Mexico