How to work out how far along I am

[User1815]

Hello, I am pregnant and I want to work out how far along I am so I can book an early scan. However when I put my details into an online calculator it says 3 weeks based on my last period starting on 17th April with a 31 day cycle. However, I only had sex 2 weeks ago, ovulated on 1st or 2nd May and presumably implanted a few days ago. So surely I'm not even one week yet?

That's how the NHS date you, all apps and online calculators will do the same. They will always go from your last missed period so generally by the time you get a positive test you are 3/4 weeks pregnant. Congratulations x

Hi. Pregnancy is always counted from the first day of your last period.
Your LMP was 17th April so you're four weeks pregnant today.

It always goes off the first day of your last period 🙂

You always date it from the first day of your last period. This is the date used until you go for your Dating Scan, at 12-14 weeks. Then the new date will be used to predict the birth and how many weeks you are may change by a couple of days.

It's rather an outmoded method of calculating pregnancy but it's how it's done.
BTW pregnancy tests which show how many weeks you are don't use the same criteria. At the moment a Clear Blue will tell you 1 - 2 weeks but that goes from ovulation.
You don't need a scan yet. Your midwife will arrange one for about 12 - 13 weeks of pregnancy.
Look online to see how you book with the midwife in your area.
Your GP practice can also tell you.

I have a longer than 'average' cycle and work it out by finding the date 14 days before I ovulated and counting from there as CD 1 of last period. That is if you want to book an early scan and dont want it too early to risk not seeing anything. NHS still go by everyone ovulating on CD 14 and having 28 day cycle so if youre longer than that you will measure behind at scans.