title: [Evaluation of time-to-pregnancy as a measure in environmental epidemiology].
abstract: Since the late 80's, time to pregnancy has been used in environmental epidemiology to explore adverse effects of different exposures. The advantages of this measure and additional elements to be considered in the performance of this type of studies are reviewed. Study design includes the following steps: population selection, sample size, outcome measurement, statistical analyses and sources of bias. Guidelines were suggested for the properly development of this type of study.
authors.affiliation: Instituto de Salud Pública, Departamento de Salud Pública y Tropical, Facultad de Medicina, Universidad Nacional de Colombia, Bogotá, D. C., Colombia. idrovoaj@yahoo.com.mx
authors.forename: Alvaro Javier
authors.initials: AJ
authors.lastname: Idrovo
authors.forename: Luz Helena
authors.initials: LH
authors.lastname: Sanín
authors.forename: Donald C
authors.initials: DC
authors.lastname: Cole
mesh_terms: D001721:Birth Intervals; D003627:Data Interpretation, Statistical; D004781:Environmental Exposure; D004813:Epidemiology; D005260:Female; D017408:Guidelines as Topic; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D011264:Pregnancy Trimesters; D015203:Reproducibility of Results; D012107:Research Design / Q000592:standards; D013997:Time Factors