There are many reasons, besides pregnancy, that could cause a delayed period. Your healthcare provider can help you sort out what may be causing your irregular periods. If you haven’t had a period for more than 90 days, speak with your provider, even if you haven’t been sexually active (2). Missed your period? Discover common signs, symptoms, and reasons for a late period beyond pregnancy, including stress, hormonal changes, and medical conditions. Learn when to seek medical advice. Learn about the possible causes of late periods, from pregnancy to stress, and how to deal with them. Find out when to see a healthcare provider and what treatments are available. Missed or late periods happen for many reasons other than pregnancy. Common causes can range from weight changes to hormonal imbalances.