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Using a Fertility Calendar to Predict Ovulation

Using a Fertility Calendar to Predict Ovulation

The calendar method predicts ovulation by looking at a woman's menstrual history. Ideally, the calendar method should be used in conjunction with other predictive strategies, like observing cervical fluids, changes in the position of the cervix, and BBT charting. Also, the calendar method can be used to determine when a woman should start using ovulation tests - products that detect her "LH Surge".

For a more comprehensive calendar method, consider creating a Fertility Chart: using several predictive methods together to pinpoint your most fertile window for conceiving.

The calendar method is designed to predict general trends based on past menstrual patterns - and is therefore limited in terms of "pinpoint accuracy". The more regular a woman's cycle, the more effective the calendar method is - and perceiving ovulation patterns begins to crystallize after a few months of maintaining records.

With the ovulation calendar method, a written record is kept using a calendar to follow the patterns of each cycle. Each cycle begins with the first day of one's menstrual period and ends with - but does not include - first day of the next (which should be recorded as the first day of the next cycle).

How Chart and Read Your Ovulation Calendar

The day menstrual flow begins is 'Day One'. Circle this date on the calendar and notate as 'Day One'. For each following month, circle Day One and continue this for for at least 7-8 months.

Continue maintaining a record of the number of days in each cycle. When bleeding starts, circle the date on your calendar.

To determine the first day you are likely to ovulate, examine your records from previous months, find the shortest cycle, and subtract 18 from the total number of days.

For example, if your shortest cycle is 28 days long, subtract 18 from 28, which leaves 10. Starting with the date you circled (Day One, the first day of your current cycle) count ahead ten days and draw an O (for 'ovulation') through that second date. This day will be the date you are most likely to become fertile.

Again, the calendar method of ovulation prediction is best used in concert with other methods discussed in the Fertility Charting section - or with ovulation predictor kits.

Download Fertility Chart


I had my last period on july 13th and my menstrual cycle is usually 34 days.When do i ovulate? and what is my luteal phase length?

i had my period last july 7, and we had a contact last july 16 and it possible for me to get pregnant?

i had my period last jul 4 and we contacted jul 12 & 14.

Is there any possiblity for me to get pregnant?

please advice!

I have my first period july 1, 2011 and lasted july 6, I contacted july 7.Am i pregnant?

Just had my menstruation last June 30 till July 4.. contacted on the 10th of July. Would there be a greater possibility of pregnancy. Thanks!

her period was on july 2, we conatcted on may 11, (withdrawal was used) can she get pregnant? please answer

i had my period may 31-3 i cant remember what date i contacted but d last was june 16. .i was expecting my period last june 30. .but until n0w i d0nt have. .am i pregnant??

err just dont work for me..

I hv bin using family planning pills but thy make me sick,so i stopped i had my periods on 30 april,2011 and contacted on the 6,am breastfeeding.can i be pregnant?plz help.

good morning! please enlighten me with my problem right now. i had my last menstruation last april 13. last contact was april 21. we did not have any contact with my husband since april 22-april 30. in my counting, i am suppose to have my menstruation by may 10-13 taking into consideration the 28-31 days cycle. until now, i haven't menstruated. i am 42 years old. i had depo as my family planning for two years since 2008-2010. my last injection was march 2010. please enlighten me with this matter. am i pregnant? thanks!

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Format: 4/23/2018
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By TTC veteran and mother of two, Elizabeth Andrews.