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Am I 4 or 6 weeks pregnant?

(6 Posts)
SarahKelbel Fri 22-Aug-14 22:59:36

Hi all,
I'm a bit confused about how pregnancy is calculated:
I understand that your pregnancy is calculated from the first day of your last period (11th July) and when entering this in to calculators I come out at 6 weeks. However, my average cycle is 36 days and not the average 28. Surely this makes a difference?
Thanks in advance for taking the time to answer me smile

hollie84 Fri 22-Aug-14 23:01:16

It does make a difference, but it doesn't really matter at this point. LMP calculation just gives you a rough idea until the 12 week "dating" scan.

ThinkIveBeenHacked Fri 22-Aug-14 23:04:30

At the moment you will be calculated against your last period and scan and appointment dates will reflect that. Once youve had yoyr dating scan, they will amend the gestation based on the size of the baby.

Lmp due date 17th April
Ovulation due date 21st April

So not masses in it yet, not enough to cause a problem with scan dates etc. There is always the possibility that you havent ovulated exactly half way through though so there will always be some potential for calculation error unless you get ovulation pain.

SarahKelbel Fri 22-Aug-14 23:28:32

Thanks so much, that's really helpful!

butternut22 Sat 23-Aug-14 08:23:23


My LMP due date was 25th Dec and my due date from dating scan is 18th Jan. With my first baby my LMP due date was 19th October and my actual due date was 17th Nov. I told the mw I have longer cycles.

It just meant I had my 12 week scans at 9 weeks both times and then went in 3 weeks later for another scan. It is quite nice to get the extra scan

JennyBlueWren Sat 23-Aug-14 08:24:56

I was exactly the same. My cycles vary in length but often up to 6 weeks. Had a due date at the beginning of Feb until the "12 week" scan when I was told I wasn't quite 10 weeks! Went back a few weeks later to get a due date of end of Feb.

At the beginning of your pregnancy it shouldn't make much difference although it might mean you see your midwife earlier as they'll see you at what they think is 8 weeks (even though you might be 6).

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