Causes

Mittelschmerz occurs during ovulation, when the follicle ruptures and releases its egg. Some women have mittelschmerz every month; others have it only occasionally.

The exact cause of mittelschmerz is unknown, but possible reasons for the pain include these:

• Just before an egg is released with ovulation, follicle growth stretches the surface of your ovary, causing pain.
• Blood or fluid released from the ruptured follicle irritates the lining of your abdomen (peritoneum), leading to pain.

Pain at any other point in your menstrual cycle isn't mittelschmerz. It may be normal menstrual cramping (dysmenorrhea) if it occurs during your period, or it may be from other abdominal or pelvic problems. If you have severe pain, see your doctor.