How to Estimate Pregnancy Due Dates

Once a woman finds out that she is pregnant, she usually wants to know her baby's due date. The due date is the estimated day for delivery. Because it is practically impossible to determine the exact moment of conception, even when sexual intercourse only happened one time, medical professionals created a system using the a woman's cycle dates, according to the American Pregnancy Association. The website states that pregnancy lasts around 40 weeks. While the baby may not arrive on the exact date, the date provides you with a bit of a guide.

Things You'll Need

• Calendar

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Instructions

Counting Weeks

• 1

  Tracking your monthly cycle is vital to determine your due date.

  Open the calendar to the day your last menstrual cycle began.

• 2

  Using a calender you can see several months on is easier.

  Count 40 weeks from that day, according to the American Pregnancy Association. Use the day of the start of the last period as the start of each week. For example, if you started your period on a Thursday, count the next 40 Thursdays.

• 3

  Mark that day as your due date.