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Help - Totally confused by impossible but official due date!

27 replies

Picklingaround79 · 14/12/2016 14:34


I (think!) I am 29 weeks pregnant, having calculated my due date all along using both the first date of my last period (24th May) and the first possible date of conception (had sex for first time in that cycle on 6th June).

However, my midwives are militantly sticking by the 'due date' given by my 12 week dating scan, which is the 24th of Feb.

As I have a 29 day cycle, this would effectively means I would have conceived before or during my last period - impossible!

I know previous threads on this have said 'what's a few days?' (or a week in my case) but it's really worrying me to the point of anxiety, as for DD's birth I had a horrendous induction experience that put both me and her at risk, and this time around I want to avoid induction at all costs.

I'm also considering having an elective C-Section because of birth trauma, and I'm worried that they will pick a date which is far too early, putting the baby at risk of respiratory problems.

Can anyone shed light on how/why the NHS believes the scan result over what the mother is telling them, and whether you can contest it in the case of choosing a C-Section date for example?

Many thanks for your help!

OP posts:
froglou · 14/12/2016 14:43

Is it possible your last period was actually implantation bleeding so you was already pregnant?

My dates are about 2 weeks out to (I'm 27 weeks now) I went for a scan at what I thought was 8 weeks going by my dates but which was actually 6 weeks and I had ovulated late. Which is the direct opposite of your situation! The edd worked out by scans are based on your baby's size and development so surely that's the most accurate?

Snowflakes1122 · 14/12/2016 14:44

Yo can refuse induction so long as it's safe to do so. They would continue to monitor you closely when overdue.

With regards to a c section, I don't know what the rules on that are, as I haven't had one. Given you are only a week ahead according to scan, so long as your over 37 weeks according to your dates baby will be full term anyway. I know my friends was scheduled for 38/39 weeks.

My son always consistently measured a week ahead of my dates (dates I was 100% on as I was tracking ovulation)

He was born 2 weeks late and a very good size. He is still very tall for his age as a toddler.

Don't worry Flowers

mimiholls · 14/12/2016 14:46

Those dates seem to add up to me. Due date of 24th Feb would mean conception around 3rd June give or take a few days which fits with what you have said. The first two weeks of the 40 weeks you aren't actually pregnant because the dating system works from first day of last period even though it is done by scan nowadays. 12 week scan is pretty accurate. They wouldn't do section before 39 weeks unless there was a medical need.

Soontobenewmummy · 14/12/2016 14:49

Hi OP, hopefully someone with medical knowledge will be along soon to put your mind at rest, but I'm pretty sure this is totally standard. When they say you're x weeks pregnant it's on the basis that you were almost certainly not pregnant for the first 2 weeks of that. I'm 39 weeks tomorrow and I've just counted back and it takes me to before my last period too - just hadn't ever thought about it!

BaronessBomburst · 14/12/2016 14:49

You can fall pregnant at any point in your cycle, including during your period. And you can still have period-like bleeding and be pregnant. So it's not impossible.

froglou · 14/12/2016 14:50

To follow
What I was told at that early scan was there's a big difference between weeks in early pregnancy, which is why the 12 week scan is the most accurate she said there's no such thing at that point as different growth rates or a faster/slower developing foetus it's either healthy or not and if it's developing at a different rate there's a problem, which is why after that 6w scan I had to go back for another at 8w to check the baby was developing at a normal rate and the dates were just out, if it wasn't it would've indicated a problem.

savagehk · 14/12/2016 14:51

What's the due date if you calculate it?

SolomanDaisy · 14/12/2016 14:52

It's only three days out.

Rustler74 · 14/12/2016 14:53

Don't pin yourself on the date of conception. They still use an age old formula to get EDD based on your last period (+12 months - 3 months + 7 days) and most of the time babies still just come when they want to or when they are ready. Only in a small percentage of pregnancies do they come on the EDD. It's just a date to use for coordination of your antenatal care.
You're well ahead of me! Wish you all the best x

heebiejeebie · 14/12/2016 14:55

Have you misunderstood or are you really anxious about 4 days?

Your last period and cycle length make your EDD 1st March

Everyone is roughly 2 weeks pregnant at the time of conception.

Lmp (last menstrual period) is used as the pregnancy start date rather than conception as more women will know that date.

savagehk · 14/12/2016 14:59

FWIW, I was moved 5 days early by my dating scan last pregnancy. I knew my dates properly as I'd been charting my temperature.

I wanted a home birth but was refused in the end because I was "more than 2 weeks" late, despite telling them all along that their date was wrong and them agreeing to use my date (I went into labour at 41+6 by my date).

You can however refuse induction, even if you are 'over 42 weeks' by scan date, if you are happy doing so - I did. You should be offered a scan to check your placenta is still OK and you are then asked to go in for fetal heart monitoring every other day.

You should also be able to pick your own elective c-section date rather than having it imposed on you? Of course there's the risk you may go into labour naturally before the c-section date, so worth asking your midwives what happens in that instance.

InTheDessert · 14/12/2016 15:14

When do you think your baby is due??
And how have you calculated that? A very quick look at a due date calculator, ignoring your cycle length as it is very close to average space me 28 Feb. 4 days is neither here nor there. Do you think your due mid march?

FlipperSkipper · 14/12/2016 15:47

I am also due on 24th Feb, my last period was 21st may which would give me an EDD of 26th Feb, but this was moved to the 24th by my dating scan. The 26th would also be my due date going by embryo transfer, as this was a frozen embryo from a previous IVF cycle, and you really don't get a more accurate conception date than when an IVF embryo was created! Personally I'm not worried about 2 days, and as others have said you can refuse induction if you feel it's too early. I'm going to be induced between 37 and 38 weeks for medical reasons and am going to be pushing to get as close to 38 weeks as I can, as long as it is safe for me to do so.

catx1606 · 14/12/2016 15:59

I have the same due date as you! 24th February. I was given the 28th going by my LMP and I thought I was exactly 12 weeks when I had my dating scan, turned out I was 12 weeks and 4 days and my due date is the 24th February. Personally I wouldn't be concerned if it's only a few days out.

ItsLikeRainOnYourWeddingDay · 14/12/2016 16:03

Sperm can live for five days in the right environment so that might be why? Also a slow developing embryo might have implanted layer. There are lots of possibles.

savagehk · 14/12/2016 16:07

itslikerain out the other way, the scan has moved her due date earlier (unless I'm misunderstanding) hence the concern about 'overdue' induction and/or early c-sec.

Picklingaround79 · 14/12/2016 16:20

Thanks everyone. Due date when I calculate it by last period is 1st March as I have a 29 day cycle. Really no chance of having got pregnant prior to the 6th June either as both of us away for work... no sex happened! Yes looked at this way it's just 5 days out but that's still important in terms of arguing against 'early' induction or c-section I feel... hence the concern.

It's really good though to hear your own experiences of due date estimation and the dating scan, good to see it's not uncommon!


OP posts:
mistermagpie · 14/12/2016 16:26

Induction/C-sections are the same as any other medical procedure in that you can refuse to have either done for whatever reasons you have. If you go 'overdue' they will just monitor you more closely. My MW told me that the latest baby she delivered was 18 days overdue and the mother had refused induction, there were some complications and the MW said it hadn't been a 'good idea' to wait so long, but that it was the patients choice.

savagehk · 14/12/2016 16:28

(I'm out this pregnancy as well by dating scan, although the scan was too late to estimate how far I was by length, so they did it by head circumference instead. Their EDD puts my LMP in the one week I know it wasn't.)

TerriB84 · 14/12/2016 16:54

No measuring system is perfect but the 12 week scan is the best estimate they have simply because most women won't know when they ovulated (and hence likely conceived, although a PP was right in saying sperm can live for 5 days in the woman's body) and many won't accurately remember the date of their last period. Once you throw in the fact that cycle length can vary by some way you can see how using anything but scan would result in wildly inconsistent due date estimates.

Annabrooke90 · 14/12/2016 19:45

Mine was put back by 4-5 days and I knew that simply wasn't possible as it Basically meant conception occurred 5 days before my positive test. It was rather scary when I started experiencing contractions at 23+4 by their dates because they don't intervene below 24 weeks at my trust, although I knew I was 100% over 24 weeks. Luckily she held on until 30+4. I do get it can be stressful when you know dates dont add up. But you can refuse induction if you do get to that stage.

Picklingaround79 · 14/12/2016 21:14

Annabrooke90 That does sound frightening. I'm really glad she held on till 30 weeks for you!
Yes, I think I will be able to more confidently refuse/delay induction if it comes to that this time around.

OP posts:
Dontwannabeabadmum · 15/12/2016 08:05

My edd was brought forward by 6 days... By lmp I was due 13/1 by 12 we scan I'm due 7/1. If I work out conception date from scan date it's impossible cos my oh was about 500 miles away that week!! Not worrying though as bubba has measured a little ahead at every scan even by just a couple days and already weighs 6lb 5 at 36 week growth scan!! I wouldn't worry too much about it if you have any concerns nearer your dd then tell them and like everyone has said you can always say no to early induction or anything if you're worried it's too early

InstantMom · 15/12/2016 08:32

None of my "official" EDDs were accurate. With ds I also was given a date that would mean I conceived during my period.

But they have to use their own methods and stick to their guns. Otherwise people would insist on dates to suit all sorts of reasons.

Fwiw I don't think the difference in your dates is going to pose any threat to your baby. If you are induced at 39 weeks their dates and your baby is really 38 weeks that's still considered term and shouldn't cause any concern. Hth and good luck with the rest of your pregnancy/birth Flowers

doingitdifferentlytoday · 15/12/2016 08:53

My IVF/Icsi baby's EDD was a week out due to dating scan at 12 weeks.

And I really did know the exact day of conception!

I had two EDD's.
This confused both consultant and myself.
We agreed to take the actual day of conception as a marker and adjust due date from this.

I can only assume the are sometimes not so precise.

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