Naegeles Rule

 

The EDC (estimated date of confinement) or EDB (estimated date of birth) is usually calculated from the menstrual history. 

 

How to calculate:

    1.  The calculation begins with the First day of the last

         menstrual period

 

    2.  From this date, go back 3 months

 

    3.  Add 7 days to the last date

 

Example:

   1.  First day of last menstrual period = March 12.

 

   2.  Go back 3 months from March 12  = December 12.

 

   3.  Add 7 days to December 12  = December 19 is the

       due date

 

Try another:

 

   1.  First day of last menstrual period = August 27

 

   2.  Go back 3 months from August 27  = May 27

 

3.       Add 7 days to May 27  = June 3  (May had 31 days)

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