What could be the reason for skipped/missed periods other than pregnancy or menopause?

Missed periods: Reasons for missed/late periods: low body weight, obesity, marked weight ^ or v, over-exercise, endurance athletics, breast-feeding, ^ stress, illness, eating disorders (bulimia or anorexia), anovulatory cycle (no egg released), travel, hormone irregularities, drug use, meds (i.e., birth control) or medical problems (i.e. PCOS). #1 reason is pregnancy.

Stress: When you are under stress, female hormones can be made less consistently which can lead to irregular periods. Eat well, sleep well, connect with nature, breathe deeply. Seek help if stress is an ongoing issue for you.

Quite a few: Besides pregnancy and menopause, the causes for irregular or missed periods can include excessive weight loss, increased exercise, emotional stress, illnesses and many medic including birth control. If this continues, pl get yourself checked by your Ob/Gyn to rule out other pelvic conditions. Also, just remember that even if you aren't having periods, you can still become pregnant!