Ovulation Facts

Each month, your body prepares for a possible pregnancy by releasing follicle-stimulating hormone (FSH), causing eggs to mature in individual follicles located in your ovaries. Each follicle produces estrogen, another hormone, which must reach a certain level for ovulation to occur. When enough estrogen has been produced -- usually 12 to 18 days after the cycle begins -- a ripened egg, smaller than the head of a pin, bursts from the most mature follicle. The release of the egg is known as ovulation.

How does it happen?

The buildup of estrogen in your follicles stimulates a surge of a third hormone, luteinizing hormone (LH). Within 24 hours of your LH surge, the egg emerges from its follicle and is immediately swept into the fallopian tubes. Meanwhile, the empty follicle -- now called the corpus luteum -- begins to produce yet another hormone, progesterone, which prevents the release of other eggs for the duration of the cycle. The corpus luteum functions for 12 to 16 days, after which your progesterone level drops and the cycle begins again.

Can I tell when I'm ovulating?

About a fifth of all women experience lower abdominal pain, known as mittelschmerz, when ovulation occurs. Breast tenderness or discomfort is also common. Most women have a vaginal discharge that is clear and somewhat elastic (try stretching it between two fingers) in the days leading up to ovulation. Ovulation predictor kits (OPKs) detect the LH surge that precedes release of the egg, while charting your basal body temperature (BBT) can be used as a marker for ovulation.

What happens to the egg after ovulation?

That depends on whether or not fertilization occurs. If the egg is fertilized within a few hours of its release, it will spend the next week or so traveling through the fallopian tubes to the uterus, where it will burrow into the uterine lining and begin the amazing process of developing into a baby. If the egg is not fertilized, it will disintegrate after about 12 to 24 hours and either get reabsorbed into the body, or pass out with the menstrual flow.