If you've missed your period but you're not pregnant, there are other reasons. Learn about hormonal change and other possible causes of a late or missed period. Amenorrhea, the absence of your period, can be primary or secondary. It may be a sign of a condition that needs treatment from a healthcare provider. Missing your period on occasion is normal. Aside from pregnancy, common causes include puberty, low body weight, menopause, breastfeeding, and PMOS. Join me for a self-paced, eight session course to learn more about amenorrhea, the science and data that support recovery recommendations, and how to change your mindset and lifestyle to get your period back. There are 2 main types of amenorrhea: Primary: Menstrual periods never start. Secondary: Periods start, then stop. Usually if periods never start, girls do not go through puberty, and thus secondary sexual characteristics, such as breasts and pubic hair, do not develop normally. Why did my period stop? Learn the common causes of amenorrhea besides pregnancy, and when to see a doctor. Wondering why you've had no periods for years? Learn the 5 critical causes behind long-term amenorrhea and why you shouldn't ignore it. Read our doctor’s guide now. An absence of menstruation, also called amenorrhea, means either that a person has not started having periods by the age of 16 or that someone who has started menstruating has missed three. Amenorrhea (uh-men-o-REE-uh) is the lack of a menstrual period, either by never menstruating or missing three or more periods or menstrual cycles. Primary amenorrhea means no first period by age 15 if other puberty changes are present, or by age 13 if they're not. It's normal to miss a period in some cases. But in others, it could be a sign of something else. Learn about the potential causes of a missed period and when to see a doctor.