Abdominal pain can be a sign of many different health concerns, but some women experience a non-threatening—although sometimes intense—pain as a normal part of the ovulation cycle. About once every 26 to 28 days, a previously immature egg in one of the ovaries develops and bursts out of the ovary. This process can cause a temporary, lower abdominal pain.
Lower abdominal pain that is one-sided and occurs about 14 days before a menstrual period is called mittelschmerz, which is German for "middle pain."
Mittelschmerz occurs at the time of ovulation, which is when an egg leaves the ovary and enters the fallopian tube. According to the Mayo Clinic, about one in five women experience pain at ovulation. The exact cause isn't known, but there are two theories. About a week before ovulation, one follicle, which is the sac containing an immature egg, begins to mature and grow. Right before ovulation, the follicle can be as large as 25 mm, and this growth may cause pain as it stretches the ovary. The second theory is that when the ovary ruptures to release the egg, blood and other fluids are also released that may irritate the abdomen.
Mittelschmerz occurs on the side in which you're ovulating but it isn't possible to predict which side, how it will feel or even how frequently you may experience it. The pain may occur every month or only occasionally. It can switch sides every month or it may be felt on the same side for several months. The duration of the pain also varies. Some women may feel it for a few minutes or a few hours; in others it may last one or two days. The type of pain has been described as a dull cramp or a sharp pain. It may be accompanied by light vaginal bleeding.
The best way to identify mittelschmerz is to keep track of your menstrual cycle for a few months. Make a note on the calendar when you experience lower abdominal pain, how long it lasts and how severe it is. It's probably mittelschmerz if it occurs in the middle of your cycle and goes away on its own.
Since it's seldom severe and is only temporary, mittelschmerz can be treated with over-the-counter pain relievers such as acetaminophen (Tylenol), aspirin, ibuprofen (Advil, Motrin) or naproxen (Aleve). A heating pad or soaking in a hot bath may help relieve pain by increasing the flow of blood and relaxing muscles. If your mittelschmerz is severe, your doctor may consider prescribing oral contraceptives because they prevent ovulation.
Pain that is experienced at any other time during the menstrual cycle is not caused by ovulation. Be sure to talk to your physician if mittelschmerz does not go away within a few days, if it's severe or if you also have nausea or fever. These symptoms could be the result of potentially serious conditions such as an ectopic pregnancy, pelvic inflammatory disease or appendicitis.