20 Week Scan As Dating Scan?

[midori1999]

I have been told that my 20 week/anomoly scan will be used to date my pregancy. Has anyone else had this? All the info I can seem to find online suggests that early dating is better.

Thanks.

Does it matter? Are the dates really that important?

Generally they don't use the 20 week scan to date, the one done at 12 weeks is a better predictor. They will measure various things though to check that the baby is growing properly and if you haven't had a dating scan they may be able to give you a date from those.

Thanks. I've had four scans already at 5+4, 6+4, 9+1 and 14+1. It is routine to use the 20 week scan for dating where I live (Northern Ireland) they say it is more accurate, just wondered as as I say, everywhere online seems to suggest early dating is more reliable. (dates in my previous scans differed from a week behind to a week ahead)

Kikijane, Dates are significant to me for a few reasons. One being my pregnancy is very high risk and in my last pregancy my twins were born at 23+5. I am at risk of having similar happen this time, and obviously around the 24 week mark a week either way is as important as it can get. Secondly, DH will and I will be living apart in seperate countries after 28 weeks, so although I am aware most babies aren't born on their due dates (DS2 and DS3 were 2 and 3 weeks early respectively) it would be nice for him to be able to get back for the birth, not least as the last one was especially unpleasant and if all goes well this will be our first surviving child together.

What I mean is that all scans will give you a date. It may vary by a few days, but like you said, it's never exact anyway.

(also, good luck with the baby. I hope everything goes full-term and perfectly for you both.)

(also, good luck with the baby. I hope everything goes full-term and perfectly for you both.)

with dd1 I didnt get a 12 week scan, the date the 20 weeks scan gave was close to the date I already have it was just changed by a few days.

Had my 20 week scan on Wednesday and was told that my due date is 28th May. My 12 week scan's due date was the 4th June-a full week later so like yourself im confused as to which is the more accurate.

My hubby works in Bahrain and as this is our first baby I really want/need him to be here for the birth but the longer he is here before I go into labour the less time he will have with us after the birth to the dating scan for us is very important.

Does anyone know which date i should use?

Hi midori1999 I'm also in NI so had dating scan at 20 weeks. I was quite curious about the difference between this and the 12 week dating scan so did a bit of hunting for info on google scholar (couldn't find anything useful on google). From what I can gather there is absolutely no difference in accuracy between the two options as long as all the calculations are done properly.

Also for what it's worth my LMP and 10 week scan (where I know they didn't try and calculate properly, just measured fetus length) were both way out compared with the date from the 20 week scan which tied in very nicely with actual date of conception.

Just re-read my post and should really point out that at my 20 week scan my due date only changed by 4 days (coming forward0 from LMP date but 10 week scan results would have had due date 4 days later.

I would also say that if they arrive at a date you're really not happy with then discuss with the midwife the reasons for why you would be happier for it to stay as it is.

Good luck I hope there is a happier outcome for you this time round