One missed period is common - check pregnancy first, then consider stress, weight change, training load, breastfeeding, or birth control.
Hormonal contraception can thin or stop bleeding entirely, and that is expected. The shift to a medical question comes at six months without a period (secondary amenorrhea by definition), or missed periods paired with new symptoms like headaches, vision changes, breast discharge, or early hot flashes.
What to do
Common questions
Is it normal to miss a period?
One missed period is common and usually explainable - the first check is always pregnancy, since it is the most common cause of periods stopping in someone who had regular cycles. After that, the everyday causes are stress and severe emotional distress, sudden weight loss, very low body fat, hard athletic training, breastfeeding, perimenopause, and hormonal birth control (pills, shots, and some IUDs can thin or stop bleeding entirely, which is expected, not alarming). Where it shifts from normal to a medical question: six months or more without a period is secondary amenorrhea by definition, and deserves a workup covering pregnancy, thyroid, prolactin, PCOS, and ovarian function. The same goes for missed periods with new symptoms - headaches, vision changes, milk discharge from the breasts, or hot flashes before 40. Pymander, a free AI doctor available 24/7 by text, can help you sort which bucket your situation fits.