For this the so called Naegle pregnancy calculation is used:

- take the first day of the last menstrual period,
- add 280 days to it,
- and than you have the big date! Your doctor will call this day EDD – estimated date of delivery.

There is a pregnancy calculator at the bottom of the post for help.

The 280 days is for a 28 day cycle, but if your regular cycle is different than 28 days, you have to increase or decrease the 280 with the same amount as your cycle is different from 28.

If your cycle is 26 days, than you have to dicrease 280 with 28-26=2, so add 278 to the date of the first day of your last menstrual period. If your cycle is 32 days, than add 32-28=4 days to 280 and calculate with 284.

Easy is not it.

What is interesting is that since your actually conceive 2 weeks later than the first day of your last period, the age of your baby will always be 2 weeks behind the age of your pregnancy. When your pregnancy is 20 weeks old, your baby is only 18 weeks old, and so forth. In general you give birth to the baby in the 40th Naegle calculated week of the pregnancy, but your baby will be 38 weeks old.

It is good to know this, because especially at the beginning it can be confusing. Doctors usually go with the Naegle calculated number.

Now here is a pregnancy calculator for you, to find the estimated date of delivery for your baby. Find the first day of your last period in the bold numbers, and see right under that the estimated date of delivery (EDD).

 Pregnancy calendar with Naegle calculation

I want this site to become the independent, community driven center of the infertility and fertility topic, where You and others can always return for advise or information.

Neither this site nor the posts or the comments substitute a certified doctor! If you read something here that could be interesting or useful for you, please ask your doctor about it before you would do any harm to yourself and/or others!

Now give me a few days to become familiar with this blog thing first and than I can fill this site up with info – hopefully with a lot of good comments from you all too.