Scan saying 6 weeks +6 days but last period makes me 8 weeks?

[Shannon9955]

Had my LMP 13th September, first positive test was October 15th. Had a scan at what should of been 6 weeks and all they saw was a yolk sac and pregnancy sac, had a rescan today, saw the baby and a pulsing heartbeat which they said www fast and strong. But they've dated me 6 weeks 6 days. I asked about it and she said that's what they've measured so that's what i am. Im just a bit confused. Is this normal? Has anyone else had this?

Is there a reason you're having such an early scan?

The NHS will go off your 12 week scan and will use that for determining your due date.

Yes, just about everyone who has a so-called "reassurance" scan has this issue. The baby is very tiny in the earliest stages and women usually find the dates match up when they have their dating scan.

I wouldn't worry at all about this.

Hi @Shannon9955 this happened to me too. Currently 21 weeks (22 weeks according to my dates!)

you cant tell when you conceived to within a week, so it is always an estimate

Same thing happened to me, I knew my dates so was concerned at my six week scan when I was "behind" (NHS scan due to previous ectopic) but by my 12 week scan they moved me ahead by a week as I anticipated based on baby's size. Baby is tiny at 6 weeks, so a tiny difference in measurement can be days/a week.

but as I say, you cant know what date you conceived, so you can be wildly out in your guess

This is normal variance. The period dating is always a bit rough, scan is more accurate, and the fact you've seen a heartbeat is fantastic - very low percentage chance of miscarriage after seeing a heartbeat.

I had a scan at 6+5, but they measured me as 6+1. The week after I had a scan at my fertility clinic and they put me back to where I was in the first place. Baby is so tiny during those first weeks I don’t think it’s a perfect science!

This happened to me too, the dates didn't match up but I didn't think too much into it... my pregnancy went well and my daughter was born at 38+3 (I was induced)

You can get it to within two days if you know when you ovulated.

OP, do you ovulate on CD14 or is it later?

I had this. Turned out i ovulated on day 29 that cycle so my dates were nearly 2 weeks out. Once we got to the 12w scan, everything started to follow the same line.

If you know exactly when you ovulated then you can probably get a bit closer, but most people don't, even ovulation predictor kits are not very specific. If you have had a scan when ovulating you will know better. unless you have IVF, then you know exactly

@secondfavouritesocks You say that (and I thought so too) but weirdly with this pregnancy I had a scan to see whether I'd ovulated yet (was on the run up to a natural FET) and the team said I had.

This turned out to be incorrect as I actually ovulated two weeks later (confirmed by temping and OPKs) and got pregnant naturally.

My dates from the four scans I've had so far line up almost perfectly with my O date (though on the last two I now measure three days ahead as I seem to have long babies lol).

@secondfavouritesocks that's true. In my case we only had sex once in the month very early on, day 8 or 9 from memory, and I was charting so I think it was an educated guess (but do get your point, it's usually impossible to know for certain when the point of actual conception occurs).

It sounds like you ovulated late? My lmp was 22nd of September but my first positive was also the 15th of October so that seems right to me? When you got your first positive was it negative before that? Because it seems all okay to me

@Givemepickles I had a stillbirth at 24 weeks with identical twins, I then went in to have 4 early miscarriages in the space of 13 months before falling pregnant with my daughter who is 19 months old and her pregnancy was uncomplicated and she was healthy.

So I'm classed as high risk for all my future pregnancies

Dating scans are standard where I am between 7/8 weeks. Via hospital.

I knew I ovulated late so went later as my period would reflect incorrectly.
Period would have put me due 8th feb but I am due the 16th and stayed that way (now 26 weeks!)

@TheBirdintheCave I have no idea when I ovulate as I've never tracked it. This was a very much unplanned surprise

Yes, so I did a cheapo tesco test and it was negative but I just knew I was. I had the feeling, got a digital clearblue and it came up pregnant 2-3

it sounds like you may have ovulated late in the cycle. which would account for a few days at least. especially if you got a negative test at first. despite what medicine says this is not an exact science. they are so tiny its hard to measure and they do grow at slightly different rates. the fact it developed a fetal pole is positive

Yeah it sounds like you ovulated late, take my pregnancy as a good example. My period was nearly 10 days after yours but we got our positive on the same day. Honestly that seems right to me!

Yes, I'd say you ovulated late. You don't say how long your cycle is usually, but I believe that assuming it's not 28 days, you don't necessarily ovulate in the middle of your cycle exactly. So someone with a 33 day cycle might ovulate on day 19 or 20.

I have PCOS so admittedly, very different, but when I discovered I was pregnant, based on when I'd had my last period, I was already 11+ weeks. I had what they treated as the 12 week scan at what my dates said was 12+2 or something like that. I knew I wasn't, and sure enough, turned out I was something like 9+5. That was actually more than I'd expected, but only because I'd taken a test and had a negative a few weeks before so I'd assumed the new positive was "newer" when in retrospect, I now realise I'd had a false negative.

It's probably nothing to worry about but do bear it in mind if they don't match up the dates with later scans. I had an issue with DD2 as I knew when she was conceived (DH working away and only back for a weekend) and the scans were 2 weeks out. She ended up being very late as the hospital insisted she wasn't conceived when I said she was and I was starting to worry that she wasn't moving about as much. So ask them to pu something in your notes now to say that you think that the dates might be out just in case you need it later on.

My early scan (private) was the same. About 8 days behind what I thought (though I wasn’t 100% on dates as baby was a surprise). By the 12 week NHS scan it had caught up to pretty much what I thought it was. DS is a healthy 19mo now. Don’t panic on early scan dates alone.

Thank you so much for the reassurance. And congratulations🥰