How are you calculating weeks? - Mothering Forums

Old 10-06-2008, 07:52 PM - Thread Starter

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I'm just curious, because I've seen some people who are due after me mention how many weeks they are, & it's usually more than I figure I am.

By my calculations I'm 19w3d. I'm due sometime between Feb 26 & March 1, depending on what calculator I use.

I figure it out by seeing how many days I am past O (122 today), then divide it by 7. Multiply the whole number (17 atm) by 7, then subtract that from the number of days past O to get the day I'm on. Then I add 2 weeks to bring it up to the "af" due date.

How's everyone else figuring out where they are?

mom to all boys B: 08/01,  C: 07/05 , N: 03/09 , M: 01/12 and far too many lost ones

Old 10-06-2008, 07:59 PM

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I did mine based on my LMP and when the Dr did my dating ultrasound it was accurate with what I figured. You can get google due date calculators and I think some do from ovulation

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Old 10-06-2008, 08:21 PM

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Holy moly, you have confused me. Let me think this out. I think I am somewhere around 15w5d by my calculations. I just add a week every Wednesday since that is the day I am "due" on. Let me see where that puts me with the way you do yours... Um, I think yours has me at 15w4d so really close.

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Old 10-06-2008, 08:30 PM

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you confused me, too... my brain hurts

the day you ovulated is 2 weeks, when your period was due is 4 weeks. so if you o'd on a monday, your period would be due 2 mondays later, and then every monday going forward you go up a week
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Old 10-06-2008, 08:44 PM

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# of weeks gestation is the # of weeks since O - so I add two weeks because I always O late and would need to adjust my LMP. I am due March 17th and today I am 17 weeks (since theoretical LMP - 15 weeks gestation).

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Old 10-06-2008, 10:13 PM

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I also just googled "due date calculator", and that was confirmed by ultrasound.

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Old 10-06-2008, 10:54 PM

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I just used an online due date calculator. Then I started spotting and went in for a u/s which put me a week and a half later than I thought (a follow up u/s followed this pattern). So mine is based on very early u/s dating.

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Old 10-06-2008, 11:05 PM

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I ovulated on a Monday, so I just count weeks since then (and taking into account that ovulation day was actually "2w" based on LMP, even though I know I ovulated on CD 12). Every Monday, I count it as having finished the last week/starting the next (in other words...er, numbers, Xw,0d).

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Old 10-07-2008, 09:04 AM

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I count back from my due date. I had a dating u/s early on so it should be pretty accurate. I'm 16 weeks 4 days. (due on March 20)
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Old 10-07-2008, 09:50 AM

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I just go with what I was told at my ultrasound appt, which is 19w5d. Which adds up based on my LMP.

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Old 10-07-2008, 10:40 AM

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Oh and I guess I should also mention that I already adjusted my due date according to when I ovulated then used one of those online calculators to figure it out. The calculators say the 24th, I say the 25th (as what I would be going by if I were having an assisted birth), and my ultrasound said the 21st. I expect to go right around those dates sometime. If I am late I will be surprised!

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Old 10-07-2008, 11:36 AM

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I think I'm 18wks and my due date is 3/8, so that jives with your method.

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Old 10-07-2008, 12:40 PM

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I also got a due date from the ultrasound, and just used a pregnancy calendar to set up a widget on my blog.

I'm not too tied up in the due date though, as I've never had an early baby. In fact, none of my babies (even Ava, whom I was on bedrest for premature labor) have been earlier than eight days when left alone.

So....all a moot point.

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Old 10-07-2008, 01:36 PM

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Since I know I ovulated on either cd 14 or 15, I count from LMP. (I had several first trimester ultrasounds due to being high risk. And my DH had chemo on cd 16 so I also know later isn't possible).
I'm due on March 5 and the way I calculate, I'm 18w 5d today.

(I have due in Feb/March in my siggy since I have to have a repeat c-section and I'm high risk - so this baby will be born in Feb. though I don't hit 40 weeks until March).
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Old 10-07-2008, 02:43 PM

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My "due date" is March 7th. Mine is based on LMP, and the date my Midwife gave me. I actually ovulated early (for me) that month, at CD 15. I have been known to ovulate much, much later than that, and maybe that's why it took me so long to get pregnant? When people ask when I'm due (IRL) I mostly just say "March" so they won't bug me about when I'm going to have the baby in case I go over 40 weeks.

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Old 10-07-2008, 03:31 PM

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I count from my O, which was cd 14. I'm 18w4d today and I'm due March 6.

Incidentally, both the wheels that my different mw's use say something different (not sure what... they are off from mine by a day or 2) which is obnoxious, since I"m counting from O. I try not to let it bug me since it's not like DomerBaby is arriving then anyway.

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Old 10-07-2008, 04:02 PM

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I actually calculated my "LMP" by counting two weeks back from my O date since I ovulate late. The babies measure exactly to that date. I'm "due" March 10th, and am 18 weeks today (Yay!)

~Danelle~ Mama to four wonderful, intact kiddos ~~ Cami (10), Jimmy (5), Ella & Alex (2/09), and Newbie due 8/11
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Old 10-07-2008, 04:23 PM

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I know when I conceived so I just typed that date into a dd calculator and came up with March 17 (although my doctor gave me an edd of March 11 based on LMP and u/s). So I am 17 weeks but a week ahead of that according to my doctor (but I'm right and he's wrong since he wasn't there when we conceived -- thank goodness!).
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Old 10-07-2008, 05:14 PM

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My DH was gone most of June (YES THE BABT IS HIS -- naughty naughty ladies :-P) And I have a crazy cycle so I guessed the date of conception, DH came home from a trip to China, woke me up at 1:30am on a Thursday night insisted that I smelled good and got all frisky, how could I forget that? When I went in and told them I thought that was the conception date, they didn't beleive me, but when they looked at the US and worked back from there it was exactly that date!! So you are your date of conception plus two weeks pregnant (so 15 weeks plus 2, I am 17 weeks)
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Old 10-07-2008, 06:53 PM - Thread Starter

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I guess the way I figured it was kind of confusing.

If I just count weeks from O & add 2, it gives me the same number, but then I have to remember when I o'd instead of just looking at the number of days, which is calculated for me in ovusoft.

It'll be interesting to see where the ultrasound puts me, even though it's totally inaccurate.

mom to all boys B: 08/01,  C: 07/05 , N: 03/09 , M: 01/12 and far too many lost ones

Old 10-07-2008, 11:40 PM

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I googled due date calculator and used my LMP since I usually ovulate around 14 days anyway (and I am pretty confident of the conception date)...based on this I am 20w3d with my due date being Feb 23rd, though I am very confident that this will be a March baby

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Old 10-08-2008, 02:03 PM

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Due date calculator online that factors in length of cycle and luteal phase.

But I have also heard you can take your lmp and subtract 3 months and then add 7 days.

I'm due around March 23 and doing the subtracting 3 months adding seven days thing I am due March 24th...so baby will come sometime in March.

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