Just took a positive test today - Due date?

[ENeale]

Hi all,
Very early days but I’ve just taken a pregnancy test today and it was a pretty clear positive! While we’re very surprised (this was unexpected), the brains are going a bit.

So I know that your due date/how far along you are is calculated based on the first date of your last period and your cycle length but what if you have irregular cycle lengths?

the first day of my last period was 16th Dec 2023. I’ll include screenshots showing this, and the last few cycle lengths I’ve had (this one shows as long because I didn’t realise I was pregnant so just ignore that).

does anyone know how I may work out specifically how far along I am in terms of weeks AND days if the lengths change? Thank you!

I don’t think you’ll get a specific answer until the 12 week scan when they measure baby, but according to the NHS due date calculator - using a 30 day cycle as a middle ground because like you said they’ve been irregular, you’d be about 5 weeks? 23rd September as a due date.

I’m pretty sure when you go for your booking scan they’ll use a 28 day cycle as their average so they might say you’re 6 weeks instead. Which would be the 21st September.

Not a massive difference but this is all guesswork, I’m no expert 😅

There's a due date calculator the nhs website.

Your initial due date is based on the first day of your last period which would give you an estimated due date of 21st September. The EDD will be confirmed at your dating scan and can move by a week or so, either way, based on the size of the baby.

As above, they will do it from your last period. Both of my pregnancies have had reasons why I knew LMP date would be off (first time by 3 weeks) and it just gets adjusted at your first scan. If you are too early for the tests, they will just invite you back a week or two later 🙂

@AprilShwrs @Mama05070704 @Springisnear4 @wannabe123

Hi all, I just wanted to say a big thank you for your replies. I'll do as advised and assume I was six weeks yesterday (every Sat). This is very nerve-wracking as a twenty-five year old woman not even living with her partner yet! But whatever happens, I'm sure we will be okay - that's what I have to tell myself :)

I have long irregular cycles, had no idea I was pregnant and couldn't actually remember when my last period was. They worked off a 28 day cycle and booked me in on my 12th week. In fact I was only 7, I just happened to have found out v early.
All it meant was they scanned, said oh you're about 7 weeks not 12, come back in a month or so

@SleepingStandingUp Oh gosh! Thank you for commenting - I’m having so many symptoms at the moment so I do feel like I must be around the 6 week mark, maybe a couple of days behind that but!

If we remove the longest and shortest lengths from your most recent cycles as they are outliers (33 and 21), then we take an average of what's left (28, 31 and 33), then we can estimate your average cycle length to be 30.66 days - let's call it 31.

So, your LMP started on Dec 16th and we think your cycle length is an average of 31 days.

That would give you a due date of 24 September and you would be 6w0d pregnant today.

Do come back and let us know