Which date do I go by?

[williwonti]

Morning. According to my LMP I am 8+6 today but when I went for an early scan (at 7 wks) they said I was 4 days behind based on the size of the "baby". Now I know that dating that early is not an exact science so am I 8+6 or should I be thinking I am actually only 8+2? I know it isn't a great difference but just wondered. I have anothe rmonth until my scan.

Mmmm, they might or might not be right, I think its very difficult to date that exactly at an early scan, so best left for another month, but at that stage every day matters, particularly if you are having a hard time! I think the LMP though is only a rough thing that doesn't work for everyone, depends on the length of your cycle, when you ovulate in it, and there can be a bit of a delay between ovulation and implantation.
So not very helpful there, sorry!

Was the scan private or NHS? If it was private I would go by your LMP date until your NHS dating scan when the dates will probably change again! If it was NHS they're likely to have amended your EDD in your notes already and that will be the date you will be working towards.

My DD went from April 4th (GP dating) to April 12th (first scan) to April 17th (second scan)...
She was born on the 21st. She measured 'under' for size...but was born weighing 10.5lbs. Me thinks someone got it wrong and she was a little over cooked.
Pregnancy is alllll about waiting.

I have just checked my diary and I think they are right. If I go by my ovulation date, that makes their date exactly right so looks like I am 4 days behind what I thought but as you say chatty, it is all about the waiting.........thanks.

My DD went from April 4th (GP dating) to April 12th (first scan) to April 17th (second scan)...
She was born on the 21st. She measured 'under' for size...but was born weighing 10.5lbs. Me thinks someone got it wrong and she was a little over cooked.
Pregnancy is alllll about waiting.

Sorry! Double post!

During this pregnancy I have been very confused about my dates. By LMP I would be due on 4/12/13. I had an early scan at which I measured 6w6d and agreed exactly with my lmp date. However my nhs dating scan brought my edd forward a week to 27/11/13. This can't be right as it puts conception date as 6/3/13. I know the dates I DTD. This being 24/2 and 9/3. I think I have finally figured it out. I concieved on 9th making the first scan behind by 3 days and the 2nd scan a head by 3 days. Based on this, I am predicting I am carrying a boy but am still waiting for the surprise at the end to see if my theory is correct. Maybe like me, you will find your 12 week scan will mean u catch up or even measure a head. Will be interesting to hear anyway.

Its not an exact science. The date you DTD in not necessarily the date you conceive. Sperm can live for up to a week, ovulation can be early or late, and implantation can take several days. All will affect the size of the embryo.

Scans aren't an exact science either, but if you know your cycles, have a couple of scan results before 12 weeks and know when u dtd, you can have a rough idea of what is more likely to have went on. Being confused about my dates, I looked up various chats on the subject and even people who had ivf and knew the exact day their baby was concieved by ifv transfer had scan dates a week out. Can only wait for the baby to come in its own time but its a bit concerning for people like myself who know their scan date is out eithwr way and will be getting a csection....which can obviously have implications if baby is born early.

scans measure the length so in theory more accurate then LMP.
ovulation and conception are so variable.

you'll have a dating scan at about 12 weeks, whatever date they give you then that will be more "accurate" and I'd go by that one