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Any midwives out there - what's the official guidance on determining due date?

(40 Posts)
FruitSaladIsNotPudding Thu 22-Nov-12 18:32:00


I have an issue - I am 40+1 today by my dates but according to my 13 week scan I am 40+6. My hospital likes to induce at 40+12. I have already declined induction at that date on the basis the dates are wrong, but my midwife wants me to go into hospital anyway to start monitoring etc on that date (next weds.)

They will not change my dates, and are putting pressure on me re. meeting the consultant next week. But I want to wait - I feel like I want to give this baby a chance to come naturally, and whilst I'm not against monitoring, I feel like it's massive overkill to start at what I know is just 41 weeks.

Btw, I was using ovulation testers when I conceived, so I am pretty certain of my dates.

What I really want to know is what is the official guidance on determining dd? I would be really grateful if any midwives/docs could signpost me to some relevant literature. They won't take my dates into account at all. I have looked at the NICE website but can't find anything.

Of course, I hope I'll have the baby before then, but I feel really stressed about this, which isn't helping!

Worley Thu 22-Nov-12 18:38:02

officially it should be done by scan dates not lmp. I can't remember our exact guidelines.. ( am Sonographer not midwife) I'm sure we leave till 2 weeks max past due date. I can check tomorrow. we have mdt tomorrow so will talk to cons.

FruitSaladIsNotPudding Thu 22-Nov-12 18:40:13

Thank you!

There is a margin of error with scans though, right? And does the timing of the scan make a big difference? ie would a scan at 8 weeks be more accurate than one at 13?

lyndie Thu 22-Nov-12 18:45:26

Hi, scan dates are more accurate - you may know when your ovulation tests were positive but you could have released the egg up to 24 hours after the positive ovulation test. Also you have no way of knowing how long implantation took, anything up to 5 days it's thought. Or if you had already ovulated but had dtd prior to the ovulation test conception could have occurred earlier. The dating scan is very accurate!

Worley Thu 22-Nov-12 18:49:32

there is a 5 day accuracy. a scan at 13 weeks would be more accurate as baby should be dated by its head circumfrance from 13 weeks. CRL before 13 weeks can be used but a edd shouldn't given from an 8 week scan.

YouSeveredHead Thu 22-Nov-12 18:53:28

I'm a big believer in scan dates but that's probay because with both of mine I was t certain of when I got of, (one was after mc with no period and scans) so to give birth the day before my due date reassured me. However I understand others may not. Why not meet the consultant anyway and get all the information?

FruitSaladIsNotPudding Thu 22-Nov-12 18:54:15

Hmm, ok. I'm not just going on ovulation tests but also lmp. My cycles are very regular as well.

mayhew Thu 22-Nov-12 20:52:12

Scan dates plot the baby size and then estimate date as if the baby was average for gestation. But of course some babies are at the larger or smaller end of the size scale. If a mother is sure of her dates by lmp/conception and the variance is 5 days or less then i go by her dates. No consultant has yet contradicted me.

FruitSaladIsNotPudding Thu 22-Nov-12 21:00:15

Wish you were my midwife mayhew!

FruitSaladIsNotPudding Fri 23-Nov-12 11:14:01

Well, my midwife spoke to supervisor of midwives and they're not willing to take my dates into consideration. They want to induce at what I believe will be 41 weeks on the nose. Or start daily monitoring.

StarlightMcKenzie Fri 23-Nov-12 20:06:30

All my 3 children were given due dates 4 days earlier than I believed were correct. The first two came on MY date due date.

When I had the scan with my 3rd and the sonographer again said baby due 4 days earlier I think I must have come across overly cocky telling her she was wrong because for some reason, despite saying it was 4 days earlier, she actually WROTE 6 days. Grrrr

Anyway, the MWs refused to do anything but go with scan date, and they were pretty determined to find it as I ad already amended my notes myself to reflect what I knew was right.

But it was all immaterial tbh because although they booked a consultant appointment for me to attend when I went overdue by 6 days my date but 12 days theirs I told them I had no wish to raise my adrenaline levels by such an appointment and risk the baby staying put for longer than he wants.

Once I made things clear I was escalated to a senior midwife who was absolutely fantastic and supportive.

MrsRadicchio Fri 23-Nov-12 22:13:08

Ooh, a quick question from me to worley or any MW reading the thread. With DS1 my edd was brought forward by 10 days. I was induced at 40+10, ie my perceived due date!

But DS was very wrinkly, red, no vernix - would this suggest that he was overdue or could that happen even if he was term?

Expecting DS2 now and dates brought forward by 5 days so a little better.

mayhew Fri 23-Nov-12 22:18:51

There is no need to start daily monitoring at 41 weeks unless there are other risk factors. 41 weeks is a normal gestation, as is 42 weeks. You can politely decline! Nor do you have to meet a consultant unless you think it would be useful.

i am a mainstream NHS mw, working in a "bog-standard" trust. We only OFFER extra monitoring after 40+12 in order for the woman to reassure HERSELF that all is well. But not all women take us up on it. Its your flipping baby, not theirs and up to you to decide about IOL or monitoring.

I've just come back from a midwifery conference where the most senior Supervisor of Midwives for the north west described how she supported a woman's decision to go 35 days after her due date! The woman was getting a lot of pressure from her local trust but the SOM told them to "back-off". She had a homebirth without complications. That's the longest i've ever heard of.

Worley Fri 23-Nov-12 22:20:50

I don't know.. the only experience of babies on the outside of the womb in rl are of my two dc (induced early with them both) and ones on scbu. sorry..
not a midwife so maybe one about can help with that bit?

brettgirl2 Sat 24-Nov-12 18:01:52

DD1 was red and wrinkly at 40+4 (dates agreed). Dd2 wasnt (also at 40+4) but I was told my placenta was gritty. Personally if I went to 41 weeks I would be requesting monitoring.

nickelbabeuntiladvent Sat 24-Nov-12 18:08:03

i think it's this document you need

just remember, they can't force you to do anything, and that NICE recommends that you aren't classed as overdue until 40+14, and that if you believe that 40+14 is different from their guess, then you can force them to go by those fates.

write it down in your antenatal notes on the "other thing i might want to ask" pages (ie the blank ones) "i believe my dates to be wrong and i am using ddmmyyyy as my due date. I insist that my birth plan is worked around this"
if you need to, force your MW to sign that she's read it.

if they start to get heavy state "i am opting for expectant management" which they will try to start from 40+12 (date of refused induction)
and quote NICE guidelines that you have read, over and over again.

and good luck smile

(ps, DD was born 40+16 and she wasn't red or wrinkly at all)(my dates were accepted as correct)

RooneyMara Sat 24-Nov-12 18:09:37

Oh this is dates have been put back by about 9 days since my 12 14+3 week scan.

I was meant to be due on 16th January according to LMP, and 13th according to when I think I conceived (OPK + temping chart) but they have me down for the 7th now.

So I'm worrying about being pressured to be induced, too.
I hope you can figure it out and do what you feel is best x

nickelbabeuntiladvent Sat 24-Nov-12 18:12:49

another link

and google "nice guidelines refusal of induction"

nickelbabeuntiladvent Sat 24-Nov-12 18:16:27

this is a copy of an article in a midwives' magazine

SchroSawMummyRidingSantaClaus Sat 24-Nov-12 18:26:31

I don't believe the dating scan is very accurate.

With DS I was using conception indicators as well and had a regular cycle. At my first scan I was pushed a week ahead then another something says ahead days ahead on another later scan.

DS was born (by induction) at 38+2 their dates and 36+5 by mines.

There could be no margin of error by my dates as we only had sex once that month and that was the day I got the positive conception test.

We were also told after a scan to expect a 9 and a half pounder, he was 6,1 when he was born. hmm

RooneyMara Sat 24-Nov-12 18:31:29

Thankyou so much for all the links Nickel smile

nickelbabeuntiladvent Sat 24-Nov-12 18:34:21

it's okay Rooney - i've been there , done that, been shouted at by an hysterical Reg who was convinced I was going to kill my babeeeeeeee

OrbisNonSufficit Sat 24-Nov-12 18:41:57

This is such an interesting thread, I've always been baffled by how this works. For those of you who know how the dating scan works - how much variance is there in baby head size during development (ie how often is the dating scan inaccurate because of big or small headed babies) and how do they know how big the baby's head is supposed to be (ie there is variance in how long a pregnancy is +/- a couple of weeks, you would only be able to measure head size:age correlation based on working backwards from birth, but you don't know if the birth is exactly at 40w therefore you don't know if the measured head size is exactly at that age IYSWIM - so surely the data must be prone to inaccuracies)?

FruitSaladIsNotPudding Sat 24-Nov-12 19:34:49

Thank you so much for the links nickel. I'm just so annoyed they won't listen to me re. dates. I know i can (and will)refuse early induction, but i don't need the stress of having the argument with them. Hardly going to help me go into labour!

I'm booked for a homebirth too, so am worried I'm going to have a battle on my hands over that as well.

Here's hoping i go into labour tonight/tomorrow!

fuckwittery Sat 24-Nov-12 19:40:58

i was told by the sonographer that there was a +/- 7 day margin of error for a scan done at 12 weeks. Just say, no thank you to induction. Ask for extra monitoring. See the consultant if you want, mine was great, it was the MW pushing for induction (even though this is extremely risky after a first c-section, risk of scar rupture much higher than the verrry slight increased risk of harm from going overdue!) consultant was happy for me to go to 40+14 with daily monitoring in the last week. in actual fact I went 18 days over due. they were also not delighted about sending a mw to my home but agreed to do so. good luck!

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