Scan EDD differs from LMP EDD - anyone else had this problem?

[Tumshie]

Hi - according to my scan date, I'm overdue (now in wk 41), but when I looked at my LMP, that would give me an EDD of 28 Aug rather than 12 Aug given by scan date...

Have spoken to hospital about this, but despite me not being sure how scan date CAN be possible IYSWIM, they are sticking to the scan date. So far I've managed to wrangle monitoring, will be going back this Weds - but am sure at some point they will want to book induction because I am 'overdue'... and I'd really like to give babe a chance to come in its own sweet time .

Has anyone else had this experience or a discrepancy between their scan date and LMP date?? I'd like more ammo if required. As it is I'm going to hospital each time armed with NICE guidelines on induction just in case...

Thanks for any info/advice!

My Edd from LMP is 8th Nov but the scan says 3/4th of Nov. Not a massive difference but I insist they stick to MY dates as I KNOW that they are accurate

Pixiefish In the great scheme of things 3-4 days doesn't make any difference. Odds are baby won't come on your EDD anyway.

Form my lmp my edd was 27th december. Scan dated it to 31st december. So nothing too bad there i guess.

FROM dammit!!!

EDD is just that - "estimated due date". In the days before scans most women knew they were expecting a bay "in April" or "in the Spring". Now there seems to be an expectation that docs can predict the exact day. Seems crazy to me, after all we don't all have the exact same menstrual cycles so why should we all have the exact same period of gestation?

Anyhoo, yes with DD2 I had a due date of 16 Aug based on LMP, moved to 12 Aug based on scan, DD finally appeared on 24 Aug. Similar story with DD1. Go figure. Both my girls had big heads - runs in DH's family - and scans predict due dates in part based on head circumference. I reckon that's why they put my due date a bit earlier.

Sounds like you are well prepared and know your stuff and are prepared to stand your ground. Good for you, and best of luck!

My main worry is that there is such a difference in my dates (16 days!!) that hospital may pressure me to go for induction - not sure how long they will tolerate monitoring, particularly given that they say scan date is more accurate. I must have v odd cycle if it is! As it is, I've been trying to encourage baby with natural induction methods (hot curry, fresh pineapple etc...) with main result that I have very active baby, poor love!! But no sign of wanting to budge, don't blame it.

Has anyone else managed to get longer monitoring??

mrsmalumbas - thanks for your input, how were the hospital/HCP with your being 'overdue', did they pressure you? Or just let you take your time? My hospital has policy of 10 days; the doctor I saw last week seemed to be OK with monitoring for the moment, but on the other hand, did mention that 'at some point I may want to book induction as slots get booked up...'.

they might have a policy - but it is your body and they can't actually MAKE you do anything.
monitoring can be anything from staying in with monitors on to seeing the m/w every day (maybe even in your home) to chack the baby's heartbeat.
Good luck and I hope everything goes ok.

With DD I didn't get a scan until 20 weeks, by which time it was too late to check (apparently). When she was born by CS at 41+3 (according to LMP) my placenta was grey and the midwife said she was very overdue.

This time round I have no LMP as I was BFing and am going on scan date, I had a scan at 5 weeks so am pretty sure they have it at least a bit right this time but you never know....but it shows that LMP can't be dead on as I don't have one! (well, I say April 2005, just to wind them up!)

Don't know what my point is but maybe you could ask for a scan to check babies size and that everything is ok if you are being pressured?

I'm think the monitoring may include scan. I'm pretty sure they test for amniotic fluid as well as baby heartbeat, and I've said I'm more than happy to attend for daily monitoring if offered, as it would reassure me and DH.

One worry I have is that my Mum had to be induced for both me and my sister, so suspect my family tends to overcook... being given such an early scan date gets me very confused. I'd rather avoid induction as from what I see can often lead to interventions etc if baby not ready. If it comes to it, and hospital say there is a problem, then obviously I'd go for it. But they may want to book me in 'just in case'. So not sure what to expect at this point...

Am really hoping baby comes sooner than my LMP date, to avoid this worry!

My VBAC baby was born at 42+1 scan date but 40+6 lmp date, 9 days difference. I had a helluva fight to refuse induction, but remember that they can't drag you in!

Of course their scan is correct, you weren't there at the conception and you have no idea about your own menstrual cycle do you?

If you don't want induction just say NO! I'd back you all the way

Kent midwifery practice's article on Induciton

Natural induction discussion on Radmid archives

Natural induction methods, remembering that the old wives tales are not considered worth trying these days! I think that anything that uses your own body's hormones is worthwhile.

also remember that baby triggers labour so there's not much point trying too hard to get it going, you're just likely to start some contractions that then fizzle out but leave you worn out if you've not slept.

Hi Klaw - thanks v much for the advice and links.

I'm booked for reflexology on Tues but am aware that nothing may happen if baby not ready to be born yet; our NCT class teacher suggested that natural induction most likely to work if baby within around 4 days of being born. However am willing to try anything just in case, so long as baby doesn't get upset by pineapple munching sessions... Perhaps will lead to lifelong aversion to pineapple?

Re cycle, as I'd only just come off pill I'm not too sure what my natural cycle would have been. Before going on the pill a few years back I was always being caught out by my period, so not too clever about these things .

Really pleased you managed to have your VBAC as planned, I think it is the idea of failed induction leading to C-section that worries me most... although friend recently had just that and after all palava of failed induction the C-section was blessed relief.

By the way, the Kent Midwifery article is great - i knew I'd seen this before but couldn't remember where. Think i will print it out and carry it around along with my NICE guidelines (saying that monitoring should be offered) just in case!!

Hi Tumshie - if your family has a tendency to long pregnancies then that explains it, there definitely seems to be something of an inherited thing. 10 days past seems to be a common "comfort zone" for most docs but they will often agree to wait especially if you agree to a session on the CTG to check that baby is doing okay. I actually asked for a stretch and sweep at 10 days past my EDD as my doula was going overseas and I really wanted her to be there for the birth - I was already 3cm dilated and it was a second baby, and I was comfortable with the risks (possible rupture of membranes etc). I did go into labour fairly soon afterwards but then I was 10 days over when I had it done so not surprising! I didn't find it painful at all, and my doc was very gentle so I was happy that I had it done. Agree with Klaw - there is a lot of evidence that it is the baby who triggers labour - as baby matures they secrete hormones which in turn stimulate the mother to produce prostoglandins which ripen the cervix and so on and so on. So it's really up to you in terms of how keen you are to avoid induction and how much you are prepared to fight your corner.

Good idea, Tumshie!! Don't underestimate the power of your own instincts either!

Ultimately tho, you call the shots, it's your baby, your body and your birth! If any recommendations are made which you are at all uncomfortable with, just ask for research based evidence to support their claims. Then you can make an informed decision.

This is the midwife we were going to have

Actually I've found some other info on internet which I might also take, re accuracy of scan dates. One, from the Perinatal Care NHS site, actually supports scan date as being more accurate than LMP date, with 95% confidence in scan date within 4-6 days (after all I may have odd cycle, I guess) - but does still give extra 6 days to play with . The other (an Australian Ultrasound Care provider) says that scan 'is within 10 days accuracy'. So this info gives me a bit more confidence in understanding how my dates could differ so much. At least these acknowledge scan date is not set in stone!

Still not sure how long I'll dare wait though, having said that - waiting beyond 28th Aug sounds like a long time. Will definitely check movements/fluid and how big bump is etc as advised.

Thanks for all your advice and support .

My dates and scan dates were very different since I have an extremely irregular cycle. LMP gave me a due date of September 6th, my early scan changed it to October 2nd, and then later scan to September 30th. I've been going by the scan date since I knew my LMP date was unreliable.

Tumshie, you may have an irregular cycle and you may just come off the pill but you are still 'allowed' to refuse induction and opt for expectant management instead. You've been doing your research, keep it up and make your own informed decisions!

Another trick to try is to forget all about dating etc and relax! Once you are not worrying about stuff and your hormones realise that you are feeling 'safe' rather than pressured, you may sudddenly be surprised by labour see this also

(Easier said than done, I accept)

BTW have they offered to try a Sweep? There are pros and cons with this but if it is successfully performed they can then give you a Bishop's Score

NAB3 - I know that babies don't come on their EDD BUT it's important for me that they take my EDD- if I go over like I did with dd then I won't want ot be induced too soon

Klaw: I think hospital may offer sweep on Weds when I go for monitoring. Thought I'd say yes, but not sure of pros and cons. Is it possible to get internal exam and ask for sweep only if cervix is beginning to look favourable?? I don't know how these things work at all. I did read on another thread that someone had two sweeps some days apart, the second of which was successful... would certainly have sweep if by doing so I avoid induction, but is there danger of waters being broken? And therefore leading to induction??

Pixiefish: suggest you print out the NICE Induction guidelines just in case, I think hospitals tend to present these as being 'after 10/14 days you should be induced' whilst forgetting the option about monitoring... perhaps useful to have printed a reminder for them!

Tumshie, yes there are risks to Sweeps, small ones, as most risks are in childbirth but then it's about weighing up what's important to you.

From my perspective and personal experience I would say not to bother. I had 3 attempts from 41wks scan edd as I was desperate for my VBAC and did NOT want chemical induction. The first, mw could not even reach cervix, the second she could barely reach and only the 3rd at 42weeks was successful, with a Bishop's Score of 8. This only showed that my body was beginning to get ready. A sweep only tells you the state of play at that particular moment in time and all could change within the hour, or not!

Now, if you are going to be going into labour anyway if a sweep is successful, is there any point risking bacteria from your vagina being taken to your cervix, having your waters accidently broken, the discomfort and indignity, or even that it can't be done and so therefore you become more dispondent?

I have decided that if I have another baby I won't be bothering with sweeps but will stay away from the hospital, get some brisk walks in, do some nipple stimulation, maybe even sex, relax, enjoy the bond me and my baby share before I have to share it with everyone else, stay well rested, well fed and watered, empty my bladder frequently, spoil my dd, enjoy some nice food, get dp to massage and pamper me and stay stress free!

But, of course, that could all go out the window when I'm dealing with pg hormones!

Listen to your instincts, what are they telling you?

Tumshie, my scan date put me about a week ahead of where I thought I was. I queried this with my consultant and he said that it's not just your LMP it's when you ovulated in your cycle. I even know that to within 2 days, as I used ovulation predictor kits, so I told him that and he said that it's not even down to just that - you may know when you ovulated but you don't know on what date you actually conceived. He was absolutely insistent that the scan is far more accurate than anything I could know. Mind you, that would explain away a week, not sure how it would account for your 16 days!

Tinkjon - I guess I wouldn't mind so much if scan date was AFTER my LMP date, as that way if baby came 'early' everything would still be OK as far as the NHS were concerned. My concern is that scan date is so much earlier than my LMP date, so baby is now considered 'overdue' by scan date, whilst not yet being anywhere near my LMP date! And I still have no idea how they can explain how scan date conception is possible, surely no-one has such an odd cycle as that ... though I accept that I may have ovulated early, which is why I'm trying to encourage baby to come with a few natural induction remedies (not overdoing it though!!).

However yesterday I found a couple of internet links from NHS/doctor websites that suggest '95% confidence' in date being between 4-6 days of scan date (or even 10 days). So scan date does NOT appear to be set in stone, even if it is presented as such. Having worked as a researcher in the past it always worries me the way that statistics can be presented...

my LMP date and scab date were 2 weeks dfferent with ds1. I had my dates as mid april and their date was 26th. when he was born on the 25th my placenta showed signs of packing in if i had gone over he would most likely have been still born
With ds2 the same midwives paid more attention to my dates towards the end but there was only a few days difference in them anyway. turns out he was 4 days later than the latest date iyswim