If you've just discovered that you're pregnant, you may be confused by your doctor's assignment of a due date. According to the American Congress of Obstetricians and Gynecologists, an average pregnancy lasts 280 days or 40 weeks. It pays to keep in mind that as with all pregnancy numbers, this date is based on averages, and only one in 20 women give birth on the actual date of delivery. Depending on your personal health and the date of conception, labor and delivery may occur two weeks before or after the estimated due date as projected by your obstetrician.
Step 1
Determine the date your last menstrual period began. This allows you to estimate the date of ovulation.
Step 2
Add two weeks to the first day of your last period. MayoClinic.com states that because women ovulate an average of 14 days after their period, this is the most likely date your egg was fertilized and conception occurred.
Step 3
Consider using "Naegle's Rule" to double-check your date of conception. According to Discovery Health, many doctors use this reverse method to determine the estimated due date: count back three months from the first day of your last period, and add seven days. Using the average pregnancy length of 40 weeks, you can now count back 40 weeks from your due date to double-check the date of conception.
Tips and Warnings
- During ovulation there will be a clear, slippery vaginal discharge as well as a slight rise in temperature one or two days after ovulation. MayoClinic.com states that because an egg must be fertilized within 24 hours of ovulation, you may estimate when conception occurs by charting your body's reactions. Other signs of ovulation may be slight abdominal cramping and tenderness in the breasts.
