Just confused about the due date they gave me...lol

So I think I am further along then what my last ultrasound said.... I go on the 17th for a sono and I will find out again...  It is keeping the hubby and I confused. According to my period I should be 14 almost 15 weeks and there telling me I am only 11 almost 12 weeks. If I try and figure out date of conception it's saying it would have been last few days of Aug. beginning of Sept.and we don't recall doing anything at that time... I thought the conception  date was Aug. 18th which would make me almost 15 weeks... I know for sure we did something then...lol... I dunno it's just been on my mind lately... So I am counting the days until next Tuesday. I mean if I am 11-12 weeks so be it... I know they will come when they are ready... So  I am going to a different hospital this time so maybe they will come up with something different...lol

 You are carrying twins though right? Maybe since there are multiples they are a little smaller and measuring a few weeks behind?

Remember that sperm can live for up to I think it's 5 days!

Hopefully they can give you a more definitive answer at your next ultrasound.

On November 11, 2009 at 8:56 AM Pacific Time, Liz R. wrote:  You are carrying twins though right? Maybe since there are multiples they are a little smaller and measuring a few weeks behind?

Remember that sperm can live for up to I think it's 5 days!

Hopefully they can give you a more definitive answer at your next ultrasound. Twins measure individually smaller, but you can expect the fundus (top of the uterus) to measure larger, but that's not really reliable until twenty-something weeks (I can't remember, & I'm too lazy to flip out of my post-partum chapers in my text); measuring the fundus can also be misleading when the mother is obese.  Did they measure the CRL to determine the babies' gestational age?  

Here's how we were taught to calculate the due date:
1st day of last menstrual period (LMP) 
minus 3 months
plus 7 days

example:  LMP was August 20
minus 3 months = May
20+7 = 27
Due day is May 27th of the next year

OH!  Forgot to add... we were told (in nursing school) that sperm can live up to 7 days!  SEVEN!  Really?!  I still find that amazing.

I had a similiar problem with Cooper.  The OB said my due date was 10 days earlier than my high-risk doctor said.

My OB's was based on my last menstrual period and my high-risk on ultrasound.  (I had regular ultrasounds - but they said the early ones are the ones they use for measurement.)

I asked them why a 10 day difference - and they said the last menstrual period is an unexact guess based on average cycle length, blah blah blah.  But the ultrasound (done early) is the best / true indication of due date. 

And they were right !  In fact Cooper was born 6 days PAST the ultrasound date -- which was 16 days past the menstrual period date. 

I wonder too if the date doesn't start until implantation --- and implantation can take from 6 days to 16 days after you do-the-deed.  

It is very confusing ! 

Cindy

See I thought the same thing sense there twins maybe they were running smaller... cuz when I got the ultra sound done I should have been 9 weeks and they said I was 6 weeks then... I was confused with the 3 week difference.I know twins come early usually... and the hubby and I have just been stumped about when we did something and when we didnt...lol 

With my daughter they gave me 5 due dates... it was 3.7.08/ 3.9.08 /3.10.08/ I was like ok those are all close together...lol but then I got 3.21.08 and 3.24.08 finally when the 24th passed still no baby so then I got induces April 1st had her April 2nd and she was huge 8lb 12.9oz  She just didn't want to come out...lol

I thought I read somewhere that even with multiples early ultrasounds (before 8 weeks) are the most accurate.   At that time all babies -- even multiples - measure the same size and you don't see variation of growth until certain stages. Because we know that all babies measure X size at X time it's the most accurate measurement. 

However -- just because your babies are 12 weeks or 14 weeks doesn't mean they will be born at exactly 40 weeks... only 5% of babies are born on their due date. 

I did find something said if you KNOW the date of conception for sure (like me - if I am pregnant I know the date, hour, minute, second the condom broke) then you can simply add 266 days to that date.  (but once again babies are rarely born on their due date.)

Good Luck!

Cindy

I don't know how they calculate these things either. When I had my ultrasound yesterday according to my last period, I should be 7 weeks 5 days, but I was measuring 7 weeks exactly. Now I know the exact day that we had unprotected sex on, it was just one time so I know the day, but they said that it can vary by a few days like that. Twins, I would think would vary even more, but I don't know that for sure.