A cross-sectional study describing aspects of menstrual poverty was analyzed with 201 female lower-secondary students in Mexico. The 15.5% indicated having a lot of knowledge about menstruation before experiencing it, increasing to 36.5% once menstruation began. Nearly 80% expressed negative or erroneous ideas about menstruation. Adolescents whose mothers have a basic educational level or lack formal education are twice as likely to not have information at the time of menarche (OR = 2.08, 95% CI 1.00, 4.33). Promoting educational initiatives would help that new generations of adolescents can live a menstruation in a dignified, safe and positive way.