How far in advance can I tell when I'm ovulating?

Predicting Ovulation

Predicting when you're going to ovulate may take many months of data gathering, and even then, you might not get an exact day of ovulation. Still, knowing the days you'll be most fertile can help you conceive. Several tracking methods can help you notice the patterns in your menstrual cycle:

Basal body temperature -- Use a basal body thermometer to track your temperature to hundredths of degrees. You'll have to take your temperature right when you wake up because if you get out of bed, you could affect the reading. Chart your results for several months. If you see a rise in temperature, that denotes when you're ovulating. This method doesn't pinpoint the exact date of ovulation, but many women ovulate within three days of this temperature shift.

Calendar -- Take note when your period starts and mark it on a calendar. This is day one of your menstrual cycle. Also, keep track of how many days it lasts. Ovulation tends to occur two weeks before you begin your period, so if you track several months' worth, you'll be able to learn how long your average cycle is, which will help you estimate ovulation. For a 28-day cycle, this will be around day 14. If you have a longer or shorter cycle, you'll likely ovulate on a different day, possibly even while you're menstruating.

Cervical mucus -- The mucus your cervix produces changes throughout your menstrual cycle. During ovulation, it becomes thin, slippery, more translucent and stretchy.

Ovulation tests -- Over-the-counter ovulation predictor kits help pinpoint your most fertile days. They test either urine or saliva for the presence of luteinizing hormone (LH). LH increases dramatically for about two days before ovulation. When you see a surge of LH, an egg will be released within 35 to 44 hours [source: Morrison]. These tests can be pricy, and like the other methods, they only tell you when you're likely to ovulate. However, you don't have to track data for months.

Although it's tough to pinpoint an exact date of ovulation, you can learn to read your body's signs to discover when you're most likely to be fertile. For even more information about ovulation and fertility, check out the links on the next page.

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