Is the scan date correct and if so how?

[peanuts_mummy]

Hi

Since my last post Ive been having a think about the scan and to me it just doesnt add up.  Tell me what you think!

I had my scan yesterday and found my baby was due a week earlier than i'd anticipated.  My last period was 13th January and I'd worked out from the pregnancy calculator that my due date was 20th October, but the lady doing the scan said I was due on 13th October.  I dont understand how this is possible as this means I got pregnant before I had my period.  She did explain it and it made sense at the time, but since I've thought about it, it doesnt make sense anymore.

Help!

[cmoretti]

We all know due dates are only a guesstimate and rarely is anyone actually born on their due date. It has been established that the "average" pregnancy is 38 weeks from conception.  Because it is difficult to nail down exact date of conception they go by the first day of AF and add two weeks to the gestational time. (which seems just as inaccurate as guessing date of conception!) With all of this, there is an assumption that everyone will conceive on CD 14. This is not true and any variation from this will alter your due date. Also, keep in mind that there is only a certain amount of cell division that can happen before implantation and that can be delayed and can also affect the age of the fetus. Implantation happens on ''average" of days 6-10, but we all have read women that come up BFP on days before that and thoses whom don't come up BFP until well after that time. Which can be a result of a very late implantation. Just take it with a grain of salt and know that it will happen when you go into labor. ;)

[shontell123]

Hi im currently 40 wks pregnant my first day of last period was on the 3rd july 08 which makes me due on the 9th april 09 and my scan is saying im due on the 19th of april i am seeing the midwife again today but she said you can go upto two weeks overdue which i dont want to as i want something done now can the midwife do something???

[SoCalTricia]

Well, yeah...no one is pregnant on their LMP. In my own case, I know my exact due date, because I know when I ovulated. (I was tracking ovulation...had the implantation dip and everything.) But, regardless of that, *most women ovulate halfway between their periods. There are always the few women who ovulation earlier or later in their cycles...but that would throw off the LMP method of determining due date by only a few days - not by a couple of weeks. So I still say that scans are misleading, as far as determining due dates. You'll get a more "correct" EDD if you use your LMP (or ovulation date if you know it).

[momof8215]

OK ladies let's think about this. Using your LMP is the "Guideline" and I choosed to believe that a scan would be more accurate considering they are measuring your baby. You ARE NOT actually pregnant when you get your LMP. A pregnancy is 40 wks from the first day of your LMP, but in reality, depending on when you actually conceived, no one is ever pregnant that long because as I said, you are not pregnant during your LMP. I would go by the scans. My children all measured big and they were big. My first was 10lbs 2 1/2oz (6 days late) My second one was 11lbs (2 weeks late-had to be induced) and my youngest was 8lbs even and that was because they induced me 3 WKS EARLY. I hope this helps. In the end, a due date is just an approximation. Babies come when they feel like it or if they are forced out

[SoCalTricia]

Yeah...what she said. LOL. Since I'm "high risk", I've had several scans. At one, the baby was due two weeks earlier...at the next, it was ten days...the last time, I was due one week before. But, *I* know when I got pregnant, so I know what the correct due date is. Ultrasound due dates are an estimate based on baby's size - there is a "normal" size range, and your baby is measured against that. Like all people, even fetuses grow at different rates - even more so the further along you get. By about 8 weeks the baby begins to grow at their own rate. Some are naturally bigger than others. If you know when your period was - without a doubt - then THAT is your "real" due date.

Tricia

[PamelaBee]

My baby is measuring 1 week ahead also...there are measurement  guidelines babys should measure at certain weeks, if your baby is measuring 1 week early, it just means certain body part measurements they took are bigger than the guidelines.  No need for worry.  It has nothing to do with your LMP date...although it may change your due date later in your pregnancy, if the baby is on the larger side.