calculating due date if no period date is available?

[jumblies]

Hi just wondering if I can accurately calculate my due date if I only have the date we had sex to go on, am still breastfeeding so haven't been paying attention to LMP and they seem to vary wildly in length at the moment anyway.

Will I have to wait till the 12 week scan to get a date?

You will probably get an early dating scan if you don't know your dates, as the nuchal scan has to be done between very definate dates

The bbc website has a pregnancy calender where you can put in the Estimated concpetion date here

thanks guys