Is it possible to get due dates wrong?

[Ally484]

I found out I was pregnant on September the 9th, and had it confirmed at the doctors on sept 10th, I have recently been wondering how I have been given a due date of June 17th for full term (I am now 34 weeks) when in my mind I definately concieved in the middle of august....I was given the due date during my scan which was 8 weeks at the time. What confuses me is that counting back from june 17th I would have concieved in the middle of september which is just not possible as I had taken over 6 pregnancy tests well before this, I was telling family at the beginning of Sept the good news and so that doesnt make sense. Counting from mid august I make my due date more like May 15th... I haven't brought it up with my consultant but i did speak to a sonographer while having my last scan and was told that the dating could not be wrong. I am bit confused. I am absolutely enormous at this point and am seriously wondering if i am actuallly 38 weeks now and  I am worried as I am supposed to be induced at 38 weeks. Is there any chance the due dates can be wrong ever? I could be well overdue when I do get induced if I dont go into labour naturally.

[kindergal]

Your placenta does not start aging until after 40 weeks...I think our nurse told us it was 42 weeks when the placenta can start to calcify.  I do not think your kiddos will want to stay in that long anyway so I would not worry about that.  There is no danger carrying them past 38 weeks...the longer they are in there, the better!

[Ally484]

My next ultra sound is on the 20th May, I feel like the babies will come well before that, and I am due to be induced in 2 weeks (at 36 weeks according to them). I mentioned my fears to the midwife at my last anti natal and she agreed it was odd but said that they generally are accurate and could not really be a month out of date.

I will ask them to look at the placenta if I make it till my next ultrasound but to be honest, I am a bit dissapointed with the sonographers that have seen me up to date because I have had a lot of conflicting information, two different sonographers have said I had 2 placentas, one said I had one placenta early on. At my last consultants appointment I was told that there is definetly only one placenta, and they have a thin membrane between the 2.

The babies are both growing as well as singletons I am told but one is slightly smaller than the other, both heads are down now also. I will see my consultant again on the 15th (friday), I intend to speak to him about the dates, I did mention something about it a long time ago and I don't think it made much impact, I just asked if it was possible to get the dates wrong from the early scan and he said it was unlikely, as he was in a rush I left it there.

If i am further along than they say is it a danger to the babies being carried past 38 weeks? Thanks for your responses..

[kindergal]

Will they be doing further ultrasounds?  If so, they will look at the age of your placenta and if you are truly beyond your due date, your placenta will show some aging.  

[Kat_624]

A due date of June 17 would match up (roughly) with you having your last menstrual period on or around Sept 10th.  So, based on what you said, yeah, that due date seems off by a few weeks.  I'd bring it up with your doc.  

Try this calculator:
http://www.medhelp.org/calculators/show/2?community_id=70

Good luck!

[jjsh44]

I'm sure it is possible that due dates can be incorrect at times.  You should definitely  bring it up to your ob and explain the story as you did here.  After all, you better than anyone knows when you conceived!!  You should put in a call first thing tomorrow especially since you are supposed to be induced at 38 weeks.  
Good luck and take care!