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Conception

When's the best time to get pregnant? Use our interactive ovulation calculator to work out when you're most fertile and most likely to conceive.

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Original poster

Conception confusion.

20 replies

IvyChime · 30/12/2018 14:34

So the date my period ended doesn't match how far along my scan says I am.
I'm really confused and have no idea how to work out when my baby was concieved.

Can't find information about it anywhere.

OP posts:

IfYouLikeALotOfChocolate · 30/12/2018 14:50

The scan is the most accurate way of dating a pregnancy

To work it out from dates simply google an online due date calculator and put in the first (not last) day of your last period

ILoveMaxiBondi · 30/12/2018 14:54

You are dated from the day your last period started. Not ended.

So if your period started on the 1st of December and ended on the 8th you would be 4 weeks pregnant today as it’s 4 weeks since the 1st of December.

Your dating scan at 12ish weeks will be the most accurate date so go with that.

ILoveMaxiBondi · 30/12/2018 14:56

If your dating scan says you are 12 weeks then you conceived 10 weeks ago. Conception take some place round about 14 days after the period starts as that’s when ovulation happens. Is there a reason you need to know when you conceived?

ILoveMaxiBondi · 30/12/2018 14:57

Takes place. Not take some place!

GeorgieTheGorgeousGoat · 30/12/2018 14:58

You go by the start date not end date.

Original poster

IvyChime · 30/12/2018 17:41

Well then it's even more wrong my period was weeks before that so I'm really confused

OP posts:

SoyDora · 30/12/2018 17:43

Maybe it would help if you give the dates?
How long are your cycles usually? Is there a reason you need to know when you conceived?

ILoveMaxiBondi · 30/12/2018 17:50

Right OP.

What date did your period start?

How many weeks did your dating scan say you are? And when did you have the dating scan?

Original poster

IvyChime · 30/12/2018 19:13

Ok sorry here are the numbers and yes I was mistaken on a few things! My apologies, really appreciate the comments thank you.

So my due date is 17th june according to my scan, which makes me 15 weeks and 6 days today (30/12/2018).
If I put that in a conception calculator it says my last period was on the 10th sept and I concieved between 19th and 23rd sept.
But I should have concieved the week before that and my last period was on 3rd sept, which is exactly a week earlier than it's saying it was which seems an odd coincidence.

So nothing matches up. Is that possible? I mean I know my dates aren't wrong which is why I'm so confused.
My periods last 5/6 days and are very regular.

OP posts:

ILoveMaxiBondi · 30/12/2018 19:19

Are your cycles 28 days? Or longer? Some women have much longer cycles.

It’s also possible that you ovulated a week later. This can happen for lots of reasons, illness or stress being a couple. Do you need to know precisely when you ovulated?

ILoveMaxiBondi · 30/12/2018 19:19

Sorry, conceived.

Original poster

IvyChime · 30/12/2018 23:26

I have no idea how long my cycles are. I've never counted. I always know when to expect it because I can just feel it and it's usually juat shy of exactly a month since the last one and that seemed normal so I never kept track, no women I know keep track tbh.

So the date of conception is definetly the week after I believed it to be?

OP posts:

C0untDucku1a · 30/12/2018 23:31

what is your concern over the dates specifically?

LaBelleSausage · 30/12/2018 23:34

Sperm can live up to 5 days in the female reproductive system so it’s entirely possible that you could have had sex on 14th, ovulated on 19th and be pregnant.

Equally, the scan could be a few days out - my last pregnancy I know for a fact the 12 week scan was out by 5 days as I know exactly when I ovulated. And I was measuring exactly right at an early scan I had at 8+2

So by that reckoning you could have had sex on 9th, ovulated on 14th and just have a baby who is measuring big if you see what I mean.

Does it matter when you conceived?

Original poster

IvyChime · 30/12/2018 23:45

I can't explain why I need to know without going into an insane amount of detail but essentially I guessed the date of conception using my period, and that made sense.
But the date the scan is saying doesn't make sense and doesn't match up with my period.

OP posts:

C0untDucku1a · 30/12/2018 23:52

The thing is, ovulation is difficult to predict without accurate cycle lengths. Nobody here can tell you when you ovulated.

Do the dates change the father?

Original poster

IvyChime · 30/12/2018 23:54

Ahh thank you that's such a relief!

OP posts:

Original poster

IvyChime · 31/12/2018 00:25

Could do yeah, essentially it's all innocent and just involves a month long break up/make up situation with my partner where I slept with a friend while single.
I didn't realize I was pregnant for a while because I'd not had unprotected sex so I didn't think it was even possible! And I had just started a new job so was very busy and preoccupied.

So we got back together before we realised I was pregnant and because we didn't know when conception had happened we went by the dates of my period, and by that logic it was definitely my boyfriend's. But the scan date makes it the other guys. I slept with him once and the condom didn't rip so that's some really bad luck if it is.

My boyfriend is happy to stick with me either way, and I'm pretty sure the other guy would sign over adoption to him as he hates kids, but I feel really upset. I want to have a child with the man I love, not some otger guy. I'm far more bothered about it than my bf is.

OP posts:

LaBelleSausage · 31/12/2018 05:09

Congratulations on the pregnancy Ivy. I can absolutely see how it could be a bit of a stressful situation but what matters is the healthy pregnancy. You can always do a dna test later if you feel strongly about it.

I know people always say the scan is totally accurate for dates but it really isn’t when you’re talking days rather than weeks. I was prepared to do battle over that when I ended up a ‘week overdue’ with DS and people started talking about inducing me, but I knew for certain I was only two days out as I’d been using ovulation strips.

Original poster

IvyChime · 31/12/2018 06:52

Oh wow, and thank you. Yeah there really is no way to tell for sure without a dna test you're right, and health is more important.

I'm trying to be positive about it. The moment I realised it might not be my bfs I started to feel like it wasn't my baby either. Which was a bit unsettling, I spoke to my bf about it and he was very reassuring, which helped.

I'll talk to a midwife about it and try to keep thinking about how much I'm looking forward to being a mum and having that first cuddle after labor.

OP posts:

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