Due date question

Okay,
Does your doctor's office determine due date by LMP or by how your baby measured at the first sonogram?
My friend (who is a nurse) was visiting me this weekend and when I told her my due date she said it was a week off. I was going by how my baby measured at the first sono. Now that I think about it, whenever I go to the doctor they said I am a week further than I thought, but that baby was measuring almost a week smaller. So I am confused! Which date is for real? I know it is only an estimate. I told my friend that I know when I ovulated, and she said it goes by LMP.
So now I don't know if I am 25 or 26 weeks pg!

ETA: I know my cycles are not 28 days, they were more like 31-35 days, so I thought the later due date made more sense.

Message edited 6/17/2007 2:01:15 PM.

Re: Due date question

LMP is just a guess. Like you said, not everyone has a 28-day cycle & even if you do, there's always a chance you didn't ovulate when you expected.

From what I've read, the early sono's are the most accurate as far as dating the pg because all fetus' develop at the same rate in the very early weeks.

So, I would go with the measurements & due date from the sono

Re: Due date question

We always went by LMP.

Re: Due date question

If you know that your cycles are more than 28 days then the later due date is the correct one...ALL of my pregnancies are "OFF" from my LMP due date b/c I ovulate late....mine is off by 2 weeks!!!!!!!!!

Re: Due date question

my OB says he always goes by the first sono, saying that is the most accurate. (later sonos, no)

Re: Due date question

Thanks! I am sticking with the later due date.

Re: Due date question

My doctor goes by early sonos, but they seem to match my LMP anyway (off by 1 day).

Re: Due date question

Re: Due date question

When I was first given my due date he went by my LMP, and then at the sono it wound up giving the same due date as my LMP, but I think the sono is more accurate bc you can actually measure the baby's growth.

Re: Due date question

I know my conception date but my Dr. used the LMP. They all do that. I am actually due 2 days early than the EDD from the dr. They did not change it though.

On all sonos, I showed about 4 days earlier than EDD by dr.

Re: Due date question

At first LMP and then confirmed it with the first sono.

Re: Due date question

Ask your dr. for the discrepancies to be sure...but most people (drs., nurses, pregnant women) go by the date of your last period.


Remember, it's all an estimate anyway...

Some women take 42 weeks to have a baby and have "perfect" 28 day cycles while some can't seem to keep a baby inside more than 38 weeks.

I'll be honest, I typically have 30-40 day cycles and yet both my children were born naturally in the 38th week!

Also, they often say the age of the baby in conception weeks instead of the same weeks you are pregnant...this threw off my DH at the Level II when the tech said the baby was 18 weeks and I was 20 weeks pregnant.

Re: Due date question

My doc goes by LMP, except if the sono measures more or less than a week from that, then they use the sono date. If that makes sense...