URL copied Delayed or missed periods? Here are the reasons Every woman is different -- including their periods. Some happen regularly and others are hit or miss and for some it's unpredictable. On average, a woman get their period every 21 to 35 days and it usually lasts about 2 to 7 days. Is your period irregular -- and if so, does it need attention? Many women are worried about a late period, but know you're not pregnant? Did you know that a delayed or a missed period happens for many reasons other than pregnancy? Common causes can range from normal physiological conditions, stress or obesity, anxiety-related issues, lifestyle changes or hormonal imbalances.