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Fertility health centre

How to guide: Ovulation calculator

One way to help increase the odds of getting pregnant is to identify the most fertile times in the menstrual cycle with an ovulation calculator, or by charting fertility.

As you go through your menstrual cycle, your body gives you all sorts of clues to indicate when you are about to ovulate. You just need to know what to look for.

How to use an ovulation calculator

One way to track your ovulation day is to use an ovulation calculator, like the one provided here by BootsWebMD. All you have to do is enter the dates of your last three periods.

Charting fertility

Charting involves:

  • Taking your basal body temperature
  • Examining your cervical mucus
  • Noting when your menstrual period began
  • Noting when you had sexual intercourse

Knowing this information can make a difference. Although around 84% of couples will fall pregnant within a year of trying, some couples who know how to determine when the woman ovulates and who have sex regularly during that time may conceive sooner. Charting can make you more in touch with your body. It's also helpful if you have questions for your GP, since he or she can see what you've been doing.

Taking your temperature

Basal body temperature (BBT) is your temperature when you wake up before getting out of bed and becoming active. It requires a special thermometer available from pharmacies. Monitoring a woman's BBT has been a time-honoured way of charting and predicting ovulation, and it's helped many women get pregnant. However, recent research has shown that it may not be as effective as experts previously thought.

Before ovulation, a woman's basal body temperature is usually consistent from day to day - for most women the figure will be about 36.1 to 36.4 degrees Celsius. During ovulation, your body releases the hormone progesterone, which results in a slightly raised temperature a day or two after ovulation - usually by 0.1 or 0.2 degrees. Your temperature will probably stay elevated until your next cycle begins. If you become pregnant during that cycle, your temperature will stay elevated beyond that.

A difference of 0.1 degree is very small, so it’s important to take the temperature in the same way every day. Also, keep in mind that the temperature change happens after ovulation, which means that once your temperature goes up, you've probably already missed your chance to become pregnant in that cycle. However, by charting your temperature every day over several cycles, you may start to see a pattern and be able to predict when you are most fertile.

WebMD Medical Reference

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