Missed period... no sex in past nine months what could be the cause ?

Missed period: Hi, too many causes including stress, heavy exercise, excessive weight loss, some medications including birth control pills, hormonal imbalance, polycystic ovaries among other causes.

Many things.: Fever, illness, stress, travel, supplements, antibiotics, exercise or diet change, weight change, either gain or loss, sleep changes, moving in with new roommate, any number of possible explanations. Do any of these things apply in your case? If you continue to have interruptions in you cycle, or continue to not have a menstrual period, you need a exam to rule out hormone and metabolic problems.

Not pregnancy! :): There are many causes for a missed period - for some women it is not uncommon to skip a month, especially if they are under stress, over exercising, or losing wt. It could also be due to hormonal issues like a low thyroid. In order to determine the cause you should see your ob-gyn especially since this has gone on for 9 months!