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Unsure how many weeks pregnant I am as I have such a long cycle

(14 Posts)
blue2711 Thu 09-Jun-11 07:09:51

I just tested positive last night and am very thrilled and excited! My last period started on 28th April but my last few cycles (I just came off the pill in December) have been 42 - 45 days. So does that affect how I calculate how many weeks pregnant I might be? Many thanks for any advice.

PenguinArmy Thu 09-Jun-11 07:38:29

Don't know but I wasn't sure of my dates so had the first scan at the earliest I could have been 12 weeks so didn't miss the testing period. I think they can date from around 7 weeks??

Booking appointments are normally at 8 weeks, but you could see your GP before this and ask their input.

Have you tested recently to help hone the dates?

bruffin Thu 09-Jun-11 07:55:30

I had longish periods of around 33-35 days. When I had my dating scan they moved my dates by a week as he was small for dates and they assumed that i ovulated 2 weeks before the end of the period rather than 2 weeks after the period started.

lolajane2009 Thu 09-Jun-11 09:21:20

my doctor and mw just dated me from the LMP as my cycle is between 37 and 42 days due to PCOS. when i went for my dating scan at 12 wekks it moved by 5 days from the 11th to the 16th.

benne81 Thu 09-Jun-11 09:35:07

Hi the only way to know for definite your dates will be when you have your first scan. As a general rule (but not an exact science) you ovulate 14 days before your next period. I had massively irregular periods 31-45 days and so figuring that out was a bit of a mystery! At my first scan they changed the due date by about a week or so, to be honest being out by a couple of weeks at the start isn't the end of the world so don't fret as it doesn't make too much of a difference. p.s. congratulations

Woodifer Thu 09-Jun-11 10:17:57

Hi I have a 35 day cycle but ovulate on about day 10 (i.e. 25 days before next period) - this took me a while to work out - because I was trying to work out when I ov'd with the sticks - but the guidance for when to start trying (based on 14 days before next period expected) meant I missed it - I conceived without the sticks on a tip from my sister :-)

Do you know when you ov'd/ conceived? Your pregnancy in weeks as talked about in the UK would then be 2 weeks at that date.

The expensive clearblue pregnancy tests can give you an indication of weeks since conception (if taken not too many weeks after).

If all else fails your dating scan (12ish weeks) should give you a good idea.

blue2711 Thu 09-Jun-11 12:31:43

Thanks for the replies. I'm afraid I have no idea about ovulation or conception as I never tested, just stopped using contraception and hoped for the best! Feel really lucky that it has happened so quickly and easily, but now have no idea whether I'm just a few weeks, or more like 6-7 weeks.

Think will have to go and get one of the expensive pregnancy tests...

What is the earliest that you can go for a private scan?

WinterLover Thu 09-Jun-11 13:14:32

You could get your GP to test your HCG levels, they did that with me as I was still on the pill when I fell pregnant...

BeeMyBaby Thu 09-Jun-11 14:38:21

blue your Dr will probably just calculate you on your LMP, using 28 days, this is what my Dr did even though my cycle ranges from 33-60 days, at the dating scan they moved my dates by a week. The expensive pregnancy test only tells you up to 3+ so if you think you're further than 5 weeks they are probably not very helpful.

loobylou13 Thu 09-Jun-11 14:55:34

You need to be at least 7 weeks before a private scan, just checked and with the baby bond company its £99

chocolateyclur Thu 09-Jun-11 15:06:12

They'll go on LMP at first until you've had a dating scan. I've had this frustration because I conceived with irregular periods, at least one failed test and it was only my second period off the pill. I was dated as having conceived in January, when I knew it was March - plus my dating scan had to be held back as I was moving areas.

You could always speak to your GP and claim absolute ignorance of your LMP - but remember that even on an early scan it can often be hard to see anything clearly before 6/7 weeks - even with an internal.

scepticalexpat Thu 09-Jun-11 15:22:43

I have long and irregular cycles and had a dating scan at 7 weeks - at that point in pregnancy the doctor told me that they are able to calculate the due date to within 1 or 2 days based on the size of the embryo. Later on it's harder to do, because later in pregnancy foetuses grow at more variable rates.

(Actually I had been doing ovulation testing, and so knew when I'd conceived, but if we'd gone by the LMP date it would have been 3 weeks out.)

Amybecomesamum Thu 09-Jun-11 17:04:00

Hi, I have a cycle of 38-43 days with pcos and the Dr and Midwife dated me from LMP. However after an early private scan after a scare my dates went back 2 weeks and apparently I conceived a few days before due on. I never knew that could happen!

blue2711 Thu 09-Jun-11 23:13:43

Thanks everyone, you've been really helpful. I'm just desperate to know how pregnant, for some reason! Hate just guessing and want it to be accurate. I'm going to see the doctor ASAP and also sort a private scan in a few weeks time. It's great that they can date so precisely at this early stage. Thanks again.

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