Why do you ask? Is baby larger than you expected or do you not see baby yet? At my first ultrasound, there was nothing visible and I was worried it might be ectopic, but at my next appointment, everything looked normal and baby was healthy.
The ultrasound is pretty accurate, but your estimated timeframe of conception might be off especially if you have had irregular periods.
My 8 week ultrasound showed I was behind almost exactly 2 weeks also.
This will be baby #4 for me and I think this is the earliest ultrasound I've had. None of my other babies measured smaller, so I think early ultrasounds aren't as accurate as they think.
All of mine were right on, due date never changed based on lmp, or ultrasound . & this is my third & I'm now 29 weeks. Id say, in my case they are very reliable... now when it comes to 5 weeks? I never had a ultrasound with any of mine until 8 weeks.
In Australia we have dating scans around 5 or 6 weeks and they sometimes do them vaginally. Not sure if they offer them in the US but they pick up a lot more than the external ones and are especially helpful and accurate early on. I actually haven't been given a choice this time around, when I booked my dating scan they told me it WILL be vaginally therefore no need to have a full bladder etc.
Maybe you could ask for one of these as it might be more accurate??
I dont agree that am US could be that far off. This post was posted a while ago and my DR assures me that these early US ate no more than 4 days either way off nowhere near 12 bc the baby would be developed or either no sac. But thanks for your comment.