Babies measuring ahead of dates?

[toomuchribbon]

Hi all, wonder if anyone can help.

Following my earlier thread, I am currently 6 weeks pregnant and away on honeymoon from week 10 to 13 + 6 and have been booked for my 12 week scan on the last day the NHS are willing to do it (13+6).

However I have been told that if the baby is measuring big when I arrive for the 12 week scan, I will be unable to have it as it will be inaccurate.

I know it is not compulsory but I want it done and want to know the result (as much as you can - I know not all things tested for, etc).

As I will be at the limit of the scan range the NHS have advised I have a private dating scan before I go away - ie at around 9 +5 - and if the baby measures big at that point then to move the 12 week scan forward and return from holiday early or in the middle of hols.

Can anyone advise how often babies measure ahead of their dates, by how much and how early can this be seen - very happy to book the private dating scan early but presumably the baby could still have a growth spurt between then and the 12 week scan?

Have read around a lot but can't find anything conclusive.

Thanks very much! :)

It's a tricky one (presume you're talking about the NT test where they measure fluid at the back of the neck as this needs to be done by 13+6 but dating is fine to do anytime after 10 weeks). I had a private scan at 9 weeks but the date at my dating/screening scan moved me on by 5 days (I thought they would as I knew I ovulated early in my cycle), they're not always that accurate before 10/11 weeks, if I had done as you're thinking of I would have missed the window for the NT measurement (nearly missed it anyway due to hospital cock up and jubilee weekend!).

If you're very worried it might be worth playing it safe and coming back early,but be aware it coud be for nothing! If you do miss the NT test they'll still be able to date you and can takes bloods for downs screening though it's not quite as accurate. Tough one, I think I'd probably be worrying all the way through my honeymoon if I thought I may miss it but it is such a shame to cut it short!

Congrats on your marriage and pregnancy and sorry to have probably not helped too much, I just wanted you to be aware that early dating isn't aways reliable!

I had my scan at what I thought was 13 weeks but it turned out I was 14+2 do baby was too big for the test. Just a quick blood test instead, no problem really. Congratulations on your pregnancy and enjoy your honeymoon

My scan was at 12 weeks on the dot, but it turned out I was 12+3 by their measurements (never mind the fact that puts date of conception before I had sex... ) so it's probably very common.

There is a blood test you can have done much later, instead, isn't there? 15-20 weeks or something - hopefully someone in the know will be able to advise better than I can.

PS - is it worth looking into a private scan in the country where you're honeymooning? Even quite poor countries have excellent private medical places; I've never been in a better hospital than the one in Bangkok... probably cheaper than flights home! :)

My dating experience was like readyforno's but they still did the NT test. The fact that they had booked me at 13 weeks and not 12 was a risk anyway! The fact that I was telling them tham my cycle was less than 28 days + midwife's mistakes put me 5 days behind in the beginning which was wrong. I thought that the scan would confirm my dates and show me "ahead" compared to their measurements, it even exceeded them!

On the other hand if your cycle is more than 30 days long there are chances they might have measured it longer and the scan will date you less than you are! That is if they don't take the cycle length into account though!

I also measured 12+3 at my scan, which by my dates was 12w exactly.

You could ask this question on the tests forum? People there may have more information on the two testing options (scan and bloods) and their relative accuracy etc.

Enjoy your honeymoon!

Dear all, thanks so much for all your replies. It's really reassuring.

Am (obviously) more than happy to return from honeymoon early for the scan but wanted to make sure that I wasn't just doing so in the overreactive manner of a newbie!

FluffyJaws (fantastic name by the way!), thank you - good idea but my hospital (UCH in London, who I trust pretty much as big teaching hosp etc) don't seem keen on using one beyond the UK if it is the only 12 week scan they will then have to go by. We're going to various Greek islands and my DP speaks some Greek, so in theory it could happen but sounds like it's best done at home.

I was tracking ovulation with 29-day cycle so am pretty sure I conceived within a certain 48-hour window but from FluffyJaws' and Stacks experience it sounds like you can still have different dates once the scan happens!

I'm not sure whether earlier is better than later in the 11-13 week window, as different hospitals seem to have different ranges but I'll do some reading round.

Thanks all :)

I was miles out with my dates. Had some bleeding in early pregnancy that I assumed was a period. At my '12 week' scan they dated the pregnancy at 16+5!! It was too late for the nuceal screening test but they were able to do a triple test instead which assessed the risk of downs, spina bifida and a few other things so it didn't really matter.

The nuceal screening isn't the only thing they're looking for on the dating scan so it's still worthwhile.

There are thousands of women who accidentally have their dating scan late because they've got the dates wrong and the hospitals are fine with that. Thats the main point of the dating scan in the first place! It sounds to me like they're just being awkward because you're trying to go against the system to fit in with a holiday and the NHS don't like anything getting in the way of the system!

I wouldn't worry too much. They should still be able to do all the checks they need, they just might gave to do it a slightly different way. Enjoy your honeymoon

toomuch I was tracking ovulation with a BBT too, it didn't seem to matter to the sonographer! :)