condition-guides

Why Is My Period Late? A Diagnostic Guide

Why your period is late depends on the cause — stress delays ovulation by days to weeks; PCOS and hypothalamic amenorrhea can stop it for months. Here's how to

Most people searching "why is my period late" are hoping for one simple answer. The honest answer is that it depends entirely on which part of the hormonal cascade is disrupted — and working through the possibilities in order is faster than guessing. The mechanism is nearly always the same: the period is late because ovulation was late or didn't happen. The period itself is triggered by progesterone withdrawal after the corpus luteum degrades — but the corpus luteum only exists if ovulation occurred. Late or absent ovulation is the proximate cause of almost every late period. Step 1: Rule Out Pregnancy If there's any possibility of pregnancy, take a test before working through other explanations. Modern urine pregnancy tests are highly sensitive (detecting hCG at 20–25 mIU/mL) and accurate from the first day of a missed period onward. A negative test 14+ days after unprotected sex is reliable. If the test is positive — that's your answer. If the test is negative, move to Step 2. Step 2: What Changed in the Past 4–6 Weeks? Most late periods have an identifiable trigger in the 2–4 weeks before the period was expected (the follicular phase — when the disruption would have had to occur