How to Calculate Birthdates

When you are pregnant, not only is it exciting to know when the baby will arrive, but it is practically a necessity to help you and your family prepare for the new arrival. It is also an important part of prenatal care, enabling your doctor to monitor the baby's development, and allowing you to gauge the progress of the pregnancy and seek medical help if necessary. It is fairly easy to calculate the due date or "expected birth date" of a new baby.

Things You'll Need

• First day of the mother's last menstrual period
• Calendar
• Pencil or sticker

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Instructions

• 1

  Determine the beginning of your last menstrual period. Write down the date or mark it on a calendar. This is the most crucial component of the task.

• 2

  Use a calendar to count exactly 40 weeks from the first day of your last period.

• 3

  Mark your calendar with a pencil or sticker to record the baby's expected due date. Using a pencil or sticker will enable you to correct the date if a doctor gives you a revised due date.