Calculating Fertility Period with Ease

Written by: Redaksi Klikdokter.com

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Fertility period is a phase in a woman's menstrual cycle in which the ovum is ready to be fertilized, and the pregnancy will most likely occur. We can easily calculate the fertile period in order to plan an appropriate pregnancy. 

 The method to calculate the fertility period consists of : 

1. Calculate the Regular Fertility Period 

This calculation is used when the woman experiences a regular menstrual cycle (e.g. every 28 days). In the menstrual period of 28 days, the first day of menstruation is calculated as Day 1, so the fertile period is Day 12 to Day 16 of the menstrual cycle.

Example:

A woman is having a period on February 2nd, so February 2nd is calculated as Day 1. Then, the Day 12 falls on February 13th and Day 16 falls on February 17th. So the fertility period is from February 13th to February 17th. 

2. Calculate the Irregular Fertility Period 

This calculation is used when the woman experiences an irregular menstrual cycle. 

The method to calculate the fertility period of the irregular menstrual cycle of 28 days is as follows : 

  1. Record the number of days in a menstrual cycle for 6 months (6 cycles). One menstrual cycle is calculated from the first day of on-going menstrual period to the first day of the next menstrual period. 
  2. The number of the shortest days in 6 menstrual cycles is subtracted by 18. This calculation determines the first day of the fertility period. The number of the longest days in 6 menstrual cycles is subtracted by 11. This calculation determines the last day of the fertility period. 

Formula: The first day of the fertility period = Number of the shortest days - 18

            The last day of the fertility period = Number of the longest days - 11

Example:

A woman is having a period with the condition : the shortest cycle is 26 days and the longest cycle is 32 days (starting from the first day of menstrual period to next menstrual period). 

The calculation : 

26-18 = 8 and 32-11 = 21.

So, the fertile period is from Day 8 until Day 21 from the first day of menstrual period.