Which EDD is more accurate - ovulation or dating scan date?

SpringTime2023 · 2023-04-15T06:59:20+00:00

I am 100% sure on my ovulation date (I get that pain) but my EDD is 5 days earlier than it would be based on dating scan. Is one more likely to be more accurate than the other? Understand baby will come when ready, but I'd rather be mindful of things re. Induction dates. Eg midwife would class me as 'overdue' 5 days earlier. Thanks

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Gloriam · 15/04/2023 09:01

I'm not 100% sure tbh. I know medically they more go off the due date based in the scan. But a babies generally tend to be born between 37-41 weeks.

tiredpuppymum · 15/04/2023 09:04

I hear you, but if you know your ovulation date then why does the NHS EDD actually matter?

You mention IOL dates... but if you know your actual edd what does it matter?

tiredpuppymum · 15/04/2023 09:04

I mean if the mw classes you as overdue 5 days earlier, why does that matter? Hope I've made sense!

Tryingtoconceivenumber2 · 15/04/2023 09:08

I had this with my first DC. By my dates I was due the 13th. I had a scan at 10 weeks and they said due 16th.

12 week scan moved me to 18th and I actually had DC on 20th. Went in to labour on my own.

After birth the midwife said that as she was so dry it was likely that she was more than 2 days overdue so I'm assuming that my original date was closer.

I've had the opposite with current pregnancy and they have moved me on 4 days. I thought I ovulated on CD13 but finding it hard to think I ovulated much earlier than this x

Original poster

SpringTime2023 · 15/04/2023 09:39

tiredpuppymum · 15/04/2023 09:04

I mean if the mw classes you as overdue 5 days earlier, why does that matter? Hope I've made sense!

I think mainly because the Trust has their policy on when they want to induce you by, and I don't particularly want to be induced. Although, I know I can decline it. I suppose I'm looking for reassurance of declining an induction sooner than needed if the research suggests that ovulation is a better predictor of how cooked a baby is.

OP posts:

Scroobydoo · 15/04/2023 12:37

Hi OP,

Unfortunately I think once the dating scan is done, the date they give the is the date on paper and can't be changed.

However you absolutely can decline induction, just be prepared to stick up for yourself. My experience was my official NHS due date was three days earlier than my 'ovulation due date'

I went overdue, luckily had a nice midwife who booked me in for the induction a couple of days later than 'protocol' because she knew I didn't want one. 41+ 5 Instead of 41+2.

I asked her not to book it at all as I knew I would decline, but she said she had to and I could just decline it on the day. It further turned out I wasn't able to ring and decline over the phone, I had to go in to decline. I think they do this on purpose in the hopes that once you're in hospital you'll go for it anyway. They put quite a lot of pressure on, made me feel a bit guilty and went over the 'risks' over and over but I was allowed to leave after some monitoring. As it happens, baby was born early morning the next day at 41+6 (or 41+3 by my dates)

Don't forget, in France 42 weeks is considered term, theres really no line in the sand and baby will come when they're ready. Dont let them pressure you just for NHS protocol!

Sorry that was long but hopefully helpful, it might be different in your trust but always helpful to hear experiences and be prepared. Good luck!

(As an aside I'd also really recommend reading Milli Hill's Positive Birth Book, or Give Birth Like a Feminist which will help with these matters)

Original poster

SpringTime2023 · 15/04/2023 13:07

Scroobydoo · 15/04/2023 12:37

Hi OP,

Unfortunately I think once the dating scan is done, the date they give the is the date on paper and can't be changed.

However you absolutely can decline induction, just be prepared to stick up for yourself. My experience was my official NHS due date was three days earlier than my 'ovulation due date'

I went overdue, luckily had a nice midwife who booked me in for the induction a couple of days later than 'protocol' because she knew I didn't want one. 41+ 5 Instead of 41+2.

I asked her not to book it at all as I knew I would decline, but she said she had to and I could just decline it on the day. It further turned out I wasn't able to ring and decline over the phone, I had to go in to decline. I think they do this on purpose in the hopes that once you're in hospital you'll go for it anyway. They put quite a lot of pressure on, made me feel a bit guilty and went over the 'risks' over and over but I was allowed to leave after some monitoring. As it happens, baby was born early morning the next day at 41+6 (or 41+3 by my dates)

Don't forget, in France 42 weeks is considered term, theres really no line in the sand and baby will come when they're ready. Dont let them pressure you just for NHS protocol!

Sorry that was long but hopefully helpful, it might be different in your trust but always helpful to hear experiences and be prepared. Good luck!

(As an aside I'd also really recommend reading Milli Hill's Positive Birth Book, or Give Birth Like a Feminist which will help with these matters)

Thanks so much, yes that's very helpful and I've started following a lot of hypno accounts who advocate for being firm on what you want / don't want. Very interesting about France! I believe their weaning guidance is also earlier, so there's always two arguments to everything isn't there.

OP posts:

tiredpuppymum · 16/04/2023 23:31

We offer induction, you don't have to accept. It really is as simple as that
Best of luck

Lhdale · 17/04/2023 06:56

I’ve had exactly the same and it really annoys me. NHS will apparently stick to their dating scan EDD. I know it’s physically impossible I am further ahead as my husband was away for two weeks and I did ovulations tests. I’ve got my 20 weeks scan coming up this week and it makes me so nervous because at the 16 week one I did privately baby was measuring at lower percentiles according to the EDD I gave them (based on my ovulation) so I’m worried NHS are going to think she’s even smaller as they will be thinking she is older than she is!

when I think about how far along I am I use my ovulation date. And just have to accept that the nhs are using a different date

tiredpuppymum · 18/04/2023 09:09

Lhdale · 17/04/2023 06:56

I’ve had exactly the same and it really annoys me. NHS will apparently stick to their dating scan EDD. I know it’s physically impossible I am further ahead as my husband was away for two weeks and I did ovulations tests. I’ve got my 20 weeks scan coming up this week and it makes me so nervous because at the 16 week one I did privately baby was measuring at lower percentiles according to the EDD I gave them (based on my ovulation) so I’m worried NHS are going to think she’s even smaller as they will be thinking she is older than she is!

when I think about how far along I am I use my ovulation date. And just have to accept that the nhs are using a different date

Well it depends how different your dates are but I'd request a consultant review if it's a huge difference. They will change the EDD if pushed and you can explain what you've explained here. Your MW can't do anything about it.