Fertile-window misclassification in period-tracking applications and associated pregnancy risk: a large observational analysis. - Brondolin, Erica; Hadengue, Bruno; Perro, Danielle; Gemzell Danielsson, Kristina; Granne, Ingrid; Nguyen, Brian T.; Costescu, Dustin J.; Wender, Maria Celeste Osorio; Berglund Scherwitzl, Elina; Scherwitzl, Raoul; Krauss, Kerry; Benhar, Eleonora (European Journal of Contraception & Reproductive Health Care, 2026)