What's more accurate - due date by scan or dates??

[somersetsoul]

If I go by my scan I'm due on Thursday. If I go by my dates I'm due a week on Saturday.

I've always believed my dates over the scan and just think this is a big baby. It's no 3 and dd2 was 8lb 12!

If your date changed from the scan, did you go into labour nearer that?? Thanks x

Mine only changed by five days but I was pretty confident about the original dates as it was confirmed by ovulation test, early pregnancy test and two early scans (I was being treated for recurrent miscarriage hence the early scans). The scan due date turned out to be closer to when I went into labour, but his weight is closer to what you'd expect for my own size if you consider him thirteen days early rather than eight - so in conclusion, who knows?!

My scan date was much more accurate than my LMP because I have irregular periods and wasn't sure when I ovulated and dates are usually based on a 28 day cycle and mine are usually longer.
Went into labour on my due date by scan and she arrived two dates later. Due date by dates was 5 days earlier

What are your dates based on? Do you know when you conceived or just basing it off LMP?

Thanks all. My dates are based on my last period. I used a period app so know it's right!

Weirdly, I gave birth exactly nine months after I ovulated. Literally to the day! Using their dates I was 8 days overdue.

Scan dates go on the development of the fetus at that particular date.

LMP used by the NHS goes on a 28 day cycle, and as most women don't have a 28 day cycle scan dates are more accurate.

When you ovulate may not be the same day as the conception date and in reality unless you have IVF it isn't known, so this is another reason why scan dates are used.

My midwife said they had to go by scan date, and DD came on that due date, which was 5 days earlier than my dates. As I’m over 40 my trust wanted to induce me on my due date but as my midwife had no concerns (and I was planning a homebirth) we agreed on induction going by the date 5 days later. I was lucky she came on my due date so I got my homebirth

Using my scan date I was five days overdue. Going by my own dates my DD arrived on the due date that I had calculated. Their dates put me at conceiving four days before we'd DTD, the condom broke, which is why I was sure of the date of conception being that day it broke or in the few days after :) and not before

My LMP due date was the 10th.
Dating scan due date 3rd.
Baby came between the two on the 7th.

Scans should be more accurate in theory as they are based on an actual physical measurement, though there will be room for error.
But babies turn up when they want, not necessarily bang on 40 weeks anyway!

My dates were based on conception (which was absolute). It put my due date 8 days after the scan due date. DS was born 38+1 by scan date but the obstetrician and peadeatrcian both thought he looked earlier than that, suggesting my dates were more accurate.

For this pregnancy dates are the same (and again I'm certain of my dates!).

Based on the scan I'm now one day over. I'm going to refuse induction based on that date, I'm convinced my dates are right!

Scan dates. You can have a rough idea of when you conceived but you'll never be 100% sure or your conception date. It takes anything up to 10 days for implantation to occur so unless you know exactly the day that happened, you won't know your exact conception date.

Scan dates don't tend to be too far off your original dates if you're sure of you LMP etc anyway

All dates are guess work. Baby will come when it comes and as long as all is well with baby and placenta and you, I'd keep refusing induction.

Due dates are not accurate either way.

It takes anything up to 10 days for implantation to occur so unless you know exactly the day that happened, you won't know your exact conception date.

I see people say this a lot but it's not true. Conception happens when sperm meets egg, and the cells start dividing then. In IVF the fertilised eggs can be replaced in the woman and so implantation (hopefully) happen at a number of points post-fertilisation but that doesn't change when conception occurred.

DS by my dates due on 21st,
by scan date due on 14th,
born on the 9th by ELCS

but I think my dates were the right ones because he was very sleepy and didn't seem "ready" to be born (unlike DD who was also a CS). He was a decent size (8.7) but very rapidly went up to the 99th centile for height and weight and has stayed there ever since. So I think he was a 9.5ish baby born 2 weeks early. but that's just my guess.

5 days over now! I'm still sure my dates are right! Saturday should be d day....

There's absolutely no way of predicting the day a baby will be born! It would be brilliant if that was true, though!

My NHS date was a week earlier than my IVF dates which were obviously correct, I had him at 38 weeks by IVF dates (39 by NHS) he was just under 9lbs, I was induced so not sure how far he would have gone

DD1 by dates 4/6 and by scan 9/6. She was born early morning on 5/6 after labour starting on 4th.

DD2 by dates 31/7 and by scan 5/8. She was born early morning of 2/8 after going into labour the previous day.

So by dates have been more accurate for me.