How to Calculate Expected Date of Delivery

Pregnancy

Determining the due date of a baby is not an exact science. The due date is calculated from the first day of the last menstrual period, not from the actual date of conception. Most women will deliver anywhere from 38 to 42 weeks. Women rarely go into labor on the actual expected due date of delivery---it's generally used as a guideline.

Things You'll Need

• Calendar

Instructions

1. Get a calendar to reference.

2. Determine the first day of your last menstrual period to the best of your ability. Mark it on the calendar. When you visit the doctor, she will ask for this date.

3. Calculate 40 weeks after the marked date. This will be your expected date of delivery.

Tips & Warnings

• You can find many due date calculators online that will do the calculations for you.

References

• Kids Health, A Week-By-Week Pregnancy Calendar, June 2008
• The Duke Encyclopedia of New Medicine; The Center for Integrative Medicine at Duke University; 2006

Resources

• Read this Article in Spanish
• Women's Health, Ovulation and Due Date Calendar