The calculation of the due birth date is by no means an exact science.

About 96% of babies DO NOT arrive on the calculated due date, no matter which existing method is used in the calculation.

AghilhaM's Method is ENTIRELY different from the existing methods.

The '266-Day' method:

This method tries to take into account the varying menstrual cycles, which is normal between different women.

This method is used by many modern medical practitioners.

The '40-Weeks' or '280-Days' method:

This calculation is again fairly straight forward.

The problem with this method is that it does not take into account, women's  longer or shorter menstruation cycle.

The 'Count-Back' method: 

A very simple calculation based on the counting back method.

Calculation of Due Date by Chart Method:

This method is just by referring the rows in a chart.



Your healthcare provider will probably refers to that magic date as your EDD - Estimated Due Date 
or EDC - Estimated Date of Confinement.

Keep in mind that the date is only just an estimation not EXACT.