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How would you calculate 'how far along' with late ovulation?

post #1 of 8
Thread Starter 
I chart, so I know my cycle, I know when I ovulated etc. My cycles are 34-44 days long, and I ovulated approx. 4 weeks into my cycle. So according to my ovulation, my very accurate due date is Feb. 24. However, how do you calculate 'how far along' in weeks I am, when it wouldn't be accurate to start from my last menstrual period?? (From lmp pregnancy is 40 weeks long/10 lunar months/9 calendar months/266 days. From ovulation it is 38 weeks- but then how do you track back???)

Does everyone get what I mean? I can be more specific if need be. And, I'm sure my questions will be answered on Monday with my midwife.
post #2 of 8
You would still count weeks as though you had ovulated on cycle day 14. With an ovulation day of June 3rd (according to your Feb. 24th due date) you are 6 weeks and 2 days pregnant.
post #3 of 8
Edit because I can't read! LOL
post #4 of 8
What I did the first time around (since I too had longer cycles and ovulated late) was adjusted my LMP start date so that it made my ovulation day 14. I just counted backwards from the date of ovulation (which I knew with certainty) and created a new LMP date. Made things so much easier for everyone to be on the same page in terms of my due date and how far along I was.

So if you adjust your LMP date to May 20, that should get you to an EDD of Feb 24.

Otherwise you're going to be two weeks behind in measuring all along, likely, and then it will bump your due date by a full two weeks, which is no good.

I'd definitely explain to your midwife about charting and knowing you ovulated week four, etc., but I strongly suggest using an adjusted LMP for all your paperwork unless you're having a homebirth and won't be dealing with anyone other than your midwife.
post #5 of 8
I've 'adjusted' my LMP by 14 days to compensate for having ovulated 'late'. (I find it amusing that it's actually simpler to do that!)
post #6 of 8
Thread Starter 
Ok, ladies, thanks for your replies! I get it now, and DreamsInDigital- you were bang on. I understand that you would have to count as if your lmp is 2 weeks before, or an 'adjusted lmp' because of the 'system' we use. Isn't it great I was charting though, because as nighten said, otherwise everything would be wayyy off? I am dealing only with my midwife, and she does look at my charts, so she would go by ovulation date too. Thanks!
post #7 of 8
I wasn't charting, and that's why I still don't know when my little one is due I have roughly 42 day cycles but the last time I got pregnant I ovulated early, so who knows!

Good on you for charting, I wish I was that organized!
post #8 of 8
I should have adjusted my LMP too. Hopefully I won't have any trouble explaining that I did not ovulate at day 14. My LMP was May 2nd, and I don't chart so I don't know exactly when I ovulated, but I have 35ish day cycles and dh didn't even get home from his deployment until May 21st so I'm thinking it was around then.
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