Due date help!!!?

When my sister originally went to the doctor they gave her a due date of March 27, 2008, but when she went to have her u/s done last Monday the estimated due date on the u/s after they measured the date was March 16, 2008. Which date is correct????????? Thanks to everyone in advance.

Due date help!!!?
Technically they are both right , there is no exact science as to when a baby is to be born , that is why there is always a two week window along with the due date two before or two after , the sono just dates according to size at this point and she could just be having a big baby and her due date is 3/27/08 or sometime between the ten day diff.
Reply:doc's and ultrasound just give an estimate of which is the due date, but the baby will probably be due somewhere in that area. the baby always come when they are ready
Reply:the due date given by the blood tests (the earliest tests) for the most part is more reliable but they are so close together i would say she will go any time in between. there is never a correct due date. it is always a guess. i hope that your sister get her bundle of joy sooner than later. i am in my last week and the wait is driving me nuts!
Reply:The ultrasound date. Until then it is just a guess based off your menstrual cycle.
Reply:the estimated due date normally goes of the ultra sound but its not for deffenant give or take 2 weeks i hope this helps
Reply:They did the same thing to me-they moved it a week earlier. And in the end, I was overdue from my original due date by 3 days!
Reply:usually the u/s in correct but it might change again mine changed twice already
Reply:The due date she was given after the ultrasound is the more accurate one.. They mesure the gestational sack size, and this gives them a more accurate date. The due date of march 27 was probably according to when her last period was... which isnt as accurate as the u/s.





good luck!
Reply:If the ultrasound is done early in the pregnancy, it's usually the ultrasound that is more accurate than the dates given, because early-on in pregnancy most normal healthy babies/fetuses grow at the same rate. It is later in pregnancy that babies will start to change/develop/gain weight at their own pace. But early-on, the things that doctors look for to guesstimate a date are usually about the same for everyone.





However, with that being said, it's not always true, and doctors can sometimes be wrong or the development of the baby might "throw-off" a guess. For example: Based on MY that I went by, I figured I would be due around May 26th. When I went for my first doctors appointment and got an ultrasound, she changed it to May 19th because she said he looked to be about a week older than what I had figured based on my dates. He ended up being born on the 27th, just a day off from what I had figured but 8 days off from what the doctor figured, so there's really no way to be ABSOLUTELY positive, dates and ultrasounds/blood levels all give just an estimate alone, it's all the items together that usually help be more accurate.
Reply:The reason the due date changed is the size of the baby. Either date could be correct or one in between. It could vary as could the size of the baby. The obstetrician usually wont change the due date officially unless its a two week difference from the original