title: [Possible bias in the selection of the control group].
authors: H E
authors: HE
authors: Velasco Mondragón
authors: A
authors: A
authors: Leyva López
authors: F
authors: F
authors: Briseño Tavez
authors: J
authors: J
authors: Escobar Meza
authors: J
authors: J
authors: Fuentes Domínguez
authors: L
authors: L
authors: Fuentes Román
authors: L
authors: L
authors: Jiménez Gallegos
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D011247:Pregnancy; D011253:Pregnancy in Adolescence / Q000706:statistics & numerical data*; D015983:Selection Bias