OUR INSTITUTES: CANCER | HEART | NEUROSCIENCE | ORTHOPAEDICS
 
 

Pediatric Health Library :: Pediatric Health Library Topics
Share |
Printer Friendly
PREGNANCY / CHILDBIRTH :: Planning a Pregnancy

Calculating a Due Date

How to calculate a due date:

A typical pregnancy lasts, on average, 280 days, or 40 weeks - starting with the first day of the last normal menstrual period (LMP) as day 1. An estimated due date (EDD) can be calculated by following steps 1 through 3:

  1. First, determine the first day of your last menstrual period.
  2. Next, count back three calendar months from that date.
  3. Lastly, add one year and seven days to that date.
Due Date Calendar
Click Image to Enlarge

For example: Your last menstrual period began on September 9, 2005. Counting back three calendar months would be June 9, 2005. Adding one year and seven days would bring you to June 16, 2006, as your estimated due date (EDD).

This three-step method is referred to as Naegele's Rule and is based on a normal 28-day menstrual cycle. Therefore, dates may have to be adjusted for longer or shorter menstrual cycles. However, even with adjustments made, less than 10 percent of women actually give birth on their calculated due dates. Delivery two weeks before or after the estimated due date is still considered normal.

You may also estimate your delivery date by using the steps 1 and 2 and the chart:

  1. First, locate the first day of your last menstrual period (in black text).
  2. Next, note the date directly below. This is your estimated date of delivery (in blue text).

Click here to view the
Online Resources of Pregnancy & Childbirth

GR_ATP

It is important to remember the health information found on this website is for reference only not intended to replace the advice and guidance of your healthcare provider. Always seek the advice of your physician with any questions you may have regarding a medical condition. If you think you may have a medical emergency, call your physician or 911 immediately.
PEDIATRIC HEALTH LIBRARY
PREGNANCY / CHILDBIRTH HOME
TOPIC INDEX
CONDITIONS
RESOURCES
GLOSSARY
RELATED LINKS:
FIND SPECIALISTS
ARTICLES
spacer

Facebook  Twitter  Pinterest  Instagram  Foursquare  LinkedIn  YouTube  RSS  CHOC Blog

US News     CAPE Award   Magnet      Beacon Award      Most Trusted Brand     Leapfrog

chocChildren's Hospital of Orange County | UCI University of California, Irvine

Children's Hospital of Orange County is affiliated with UC Irvine Healthcare and UC Irvine School of Medicine

CHOC Children's - 1201 W La Veta Ave, Orange, CA. Phone: 714-997-3000. .