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Calendar method and more: How to know when you are fertile

Whether planning to conceive naturally or by artificial means, it is important to know when you are fertile. Find out using the calendar method and more!

A woman’s ovulation calendar changes every time, which can be a struggle to some especially when you are trying to have a baby, or for others, avoiding getting pregnant. It is advisable to be aware of your own ovulation calendar by knowing and tracking your menstrual cycle from day one. Calendar method is just one of the natural ways to know when your fertile days are.

ovulation calendar

Calendar method

Having an accurate ovulation calendar differs from one woman to another. The calendar method is one way of knowing when your most fertile days are – if you would like to conceive – or as a natural birth control to know when you should be having intercourse without the risk of getting pregnant.

First, chart the length of your menstrual cycle, starting with the first day of your menstrual period as Day 1 and doing so continually until your next period starts again, after which you start counting for a new menstrual cycle. For this method to be reliable, you need at least three to four menstrual cycles to be able to predict when you are most fertile in your ovulation calendar. Know the duration of your cycles, and take note of the shortest and longest cycles.

Here’s a little math:

Note your shortest cycle (ex. 27 days), and subtract 18 from the total number of days (27 – 18 = 9).

If the first day of your current menstrual period is May 4, add 9 days (including the first day), and this will give you the approximate first fertile day in your ovulation calendar (May 4 + 9 = May 12 is the first fertile day).

To know the last fertile day in your ovulation calendar, take your longest cycle (ex. 30 days) and subtract 11 from the total number of days (30 – 11 = 19). From May 4, add 19 days (including the first day) to give you the approximate last fertile day (May 4 + 19 = May 22 is the last fertile day).

Whether conceiving or avoiding pregnancy, look out between these fertile dates to either have intercourse or avoid doing so.


Basal Body Temperature (BBT)

Another method of knowing your ovulation calendar is by tracking the rise in your body temperature when at rest. To be able to chart your ovulation calendar, you should take your body temperature with a basal thermometer, which measures temperature at 1/10 of a degree, ideally first thing when you wake up before doing any activity as this is when your body is still at rest.

A woman’s basal body temperature (BBT) is said to rise when a woman is ovulating. This may not give a consistent accurate reading of your ovulation calendar, but may be reliable when you can time sexual intercourse with your partner, as this is based on how your body reacts to the hormones released during ovulation.

Billings Method

Billings method is a natural birth control method done by checking your cervical fluid or vaginal discharge. Your vaginal discharge constantly changes in reaction to the hormones produced throughout your ovulation calendar. Right after menstruation, cervical fluid may start out as yellowish, white or cloudy. The nearer you are to ovulation, then it becomes clearer and more stretchy, somewhat resembling raw egg whites.

Here’s a tip: when you feel most wet is when you are likely to be most fertile.