How to Calculate Due Date by Conception Date

Pregnancy is an experience filled with uncertainties and surprises. Women can eliminate part of the guessing game associated with pregnancy by using the conception date to estimate their baby's due date. Keeping in mind that only about 5 percent of babies are delivered on the expected due date, the calculation should be treated as an estimation, as opposed to a definitive answer.

Things You'll Need

  • Conception date
  • Date of last menstruation before conception

Instructions

    • 1

      Identify the date of conception.

    • 2

      Identify the first day of the last menstruation you had before conception. Estimate when your last menstruation began if you are unsure. Conception usually takes place somewhere between 11 and 21 days after the beginning of menstruation. Identify the date that is 16 days--the midpoint of the conception timeframe--before the conception date.

    • 3

      Add 40 weeks, or 280 days, to the beginning date of your last menstruation. The result will provide your baby's estimated due date.

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