Mittelschmerz occurs when a woman's ovary releases a mature egg during ovulation. In a typical 28 day menstrual cycle, this usually happens around day 14. The sensation varies from slight cramping to severe pain. It's often felt on only one side, although the side will likely change from month to month. If a woman doesn't have regular menstrual cycles, ovulation is difficult to predict and the sensations of mittelschmerz may seem to occur at random.
The pain can range from slight to severe and distressing for some women. Often described as a sharp or stabbing distinctive cramping sensation, mittelschmerz is sometimes mistaken for appendicitis, indigestion, or very bad gas. Although it may be very uncomfortable, painful ovulation does not indicate a medical problem and doesn't require any treatment other than measures to relieve the discomfort.
A warm bath, a heating pad on the abdomen, and over-the-counter analgesics may offer some relief. The discomfort typically lasts 6 to 8 hours, but can persist for up to 48 hours for an unlucky few. If the pain becomes unbearable or accompanied by heavy bleeding or fever, a visit to the doctor is warranted.
It's not clear exactly which processes of ovulation are to blame for the pain, but one explanation is that the swelling follicles cause uncomfortable stretching of the ovary. Another hypothesis is that the small amount of blood and fluid released from the follicle when it bursts during ovulation may irritate the abdominal lining. A third possibility is that contractions of the fallopian tubes are the source of the cramping.
If a woman is trying to conceive a baby, instead of dreading mittelschmerz, she may actually welcome the sensation of ovulation. Knowing when ovulation is about to occur is the “jackpot” sign of fertility and worth a little discomfort for those trying to conceive. It's important to note that the best time to have sex to conceive is in the days leading up to and including the day of ovulation. If a couple waits for mittelschmerz pain to initiate intercourse, they may be too late for conception. Instead, they should record on which day of her cycle ovulation pain typically occurs. In the months they are trying to get pregnant, they should have sex every day 4 to 5 days before and including her predicted ovulation date and 2 to 3 days after.
Women who don't notice ovulation pain shouldn't be concerned. 80% of women never report experiencing mittelschmerz but that is not an indication of fertility problems.
For women not trying to conceive, mittelschmerz is likely more trouble then it's worth. Unfortunately the best long-term cure for the pain is cessation of ovulation all together, either through menopause or by taking hormonal birth control that eliminates ovulation.