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# How to Calculate Conception Date From Due Date?

How do you find the date of conception from estimated date of delivery (EDD)?

## Calculate Date of Conception from EDD

This tutorial helps you find the Date of Conception based on an average 28 days menstrual cycle for women using the EDD (Estimated Due Date of Delivery). The Date of Conception is the probable date of sexual intercourse that lead to the pregnancy. Know how to calculate conception date from date of delivery (EDD) using this tutorial.

Formula: Dates of Conception using EDD:
This tutorial calculates the probable date of conception based on the EDD (Estimated Date of Delivery) considering the mensutrual period to be a regular 28 days cycle.

As per the Naegeles rule, the expected date of delivery (EDD) is calculated by adding one year, subtracting three months, and adding seven days to the first day of a womans last menstrual period (LMP). The result is approximately 280 days (40 weeks) from the start of the last menstrual period. Hence the formula for finding date of conception is given below as:
Possible Dates of Conception (PDC) = (PDO - 4 days) to (PDO + 4 days)

Where,
PDO (Probable Date of Ovulation) = 1st day of LMP + 14 days
1st day of LMP = EDD - 280 days

Finding Dates of Conception using EDD: Example:
Consider the below example. Find the possible dates of conception, where the EDD (Estimated Date of Delivery) is given as March 15, 2017.
The EDD (Estimated Due Date of Delivery) could also be calculated with the given 1st day of LMP, which is 40 weeks from the start of last menstrual period.

1st day of LMP
= March 15, 2017 - 280 days
= June 8, 2016

PDO (Probable Date of Ovulation)
= June 8, 2016 + 14 days
= June 22, 2016

PDC (Possible Dates of Conception)
= (June 22 - 4 days) to (June 22 + 4 days)
= June 18, 2016 to June 26, 2016

Hence the possible dates of conception for the given EDD March 15, 2017 should be probably between June 18, 2016 and June 26, 2016.