Approximately 20 percent of women notice pain during ovulation.  This pain, called mittelschmerz, occurs around the middle of a woman’s cycle. Ovulation pain, or pain around the time of ovulation (since it doesn’t necessarily happen at the very moment you ovulate), varies from woman to woman. Some experience a dull, achy feeling, which lasts for a few hours or even over a couple days. Other women experience a sudden, sharp pain, lasting just a moment.

Does “Ovulation Pain” Really Signal Ovulation?
Ovulation pain does seem to coincide with ovulation, with one study finding that ovulation pain came on the same day that the hormone LH peaked. (LH is the hormone detected by ovulation predictor kits, and generally signals your most fertile time). Another study confirmed ovulation using ultrasound, finding that ovulation occurred within a couple days after reporting of ovulation pain. Ovulation pain may not be recommended as a primary way to detect your fertile window, but it can help confirm other signs of ovulation.

Why Does Ovulation Pain Occur?
No one is really sure what causes ovulation pain. A few theories are that the extra fluid, released when the follicle ruptures releasing the egg, causes some irritation, leading to a dull ache.

Another theory is that the sharp, sudden pain some women feel may be caused by the egg itself, bursting out from the follicle. Spasms of the fallopian tubes or uterus as ovulation approaches may be another possible cause.

Here’s something interesting about ovulation pain: the side you feel it on may signal which ovary you actually ovulated from. You may notice that the pain is more frequently on one side than the other. While you may have been taught that the ovaries “take turn ovulating” from month to month, it’s actually normal for one side to do more of the ovulating work than the other.