Is an ultrasound dating with no given LMP based from when the baby was likely to be conceived?

[mlrrr]

Hello everyone, I'm wondering if anyone else has ever experienced this or have any understanding.

So at my dating scan on the 21st of September I was measured at 15+2 and my EDD is the 13th of March. When I attended my midwives appointment the other day I was a complete mess because during the month of June I slept with two people. I won't go in to too much detail as the midwife ruled out the second as this was at the end of June and she states I conceived very early on in June so would have already been 2 weeks pregnant by the time I slept with the other guy on the 20th.

I know that most midwives across the UK calculate gestational age by LMP however I wasn't asked. I live in Scotland so I'm not sure if things are measured differently and I was reassured by my midwife that I conceived early June but when I read different forums and articles this all goes against what she says.

According to the book I was given, in the section about the growth of my baby it states that during the first week conception occurs and implantation begins. However, everything else that I've read states that in the first two weeks of pregnancy you aren't actually pregnant, your body is preparing itself.

I'm in such a mess and starting to feel very anxious and overwhelmed by this situation. I trust my midwife but because this is my first pregnancy I'm unsure and this is all really new to me.

So to clarify is an ultrasound dating with no given LMP based from when the baby was likely to be conceived?

I'm sorry for rambling but any insight would be appreciated.

Hi, sorry this must be stressful,
My understanding is;

When conception happens you are 2 weeks pregnant already. The first two weeks the egg is developing and being released but has yet to be fertilised. So implantation etc. is week 3.

They go on LMP initially as they have nothing else to go on, but it's flawed because everyone has different cycle lengths and ovulate at different points in their cycle so the margin for error is really quite big.

Once you've had a scan the dating in this is seen as much more reliable, because it's based on the size of the foetus. At my scan I was told the margin for dating is 2 days either way.

Our dates are actually very similar, my EDD is March 16th. I conceived around June 26th/ 27th so I would think that your later date is more likely than the earlier one for conception.

Hope that helps.

Hey thanks for commenting @JuneySunshine!

From what you have shared everything I have read up on says the exact same. I am so confused as to my midwife would misinform me like this. Makes no sense whatsoever.

I do think she thought I was being very silly and overly anxious with regards to the situation because I shared with her around my fertile period I had regular sex with who I assume to be the baby's dad on the 17th, 18th and 19th and when I had sex with my friend on the 20th it literally lasted 2 minutes because we both decided it was awkward so he didn't finish. I am aware about precum and how it can sometimes contain sperm.

I think since things are starting to get serious between me and the baby's dad I am starting to feel really guilty which is why I'm starting to overthink and become very anxious and depressed about the situation. I know some people will probably judge but I'm young and just wasn't thinking straight at the time.

Hi, don’t mean to sound like I am being horrible, this is just my opinion. I think you should just be honest and tell him that you have slept with someone else before you got serious. With the dates being so close together I think it’s going to be impossible to tell unless you do a dna test. If you do this on the quiet when the baby is born and then find out it’s not actually his, how is he going to feel then!! A lot more angry than he would be if you told him now. Obviously if your friend did it finish then it’s much more likely to be the other one but you never know really.

No problem.

I do think she has it wrong with early June and is confusing week 0 and week 2, just an innocent mistake.

From what you've said it sounds like the overwhelming likelihood is that the guy who you want to be the baby's dad is the father- you had a lot of sex and his sperm can then live for 5 days inside you.

Don't beat yourself up about the situation. It's just a case of deciding what's best for you now- if you're able to let things be or if you need to know for sure. I've seen other threads on here about DNA testing etc. if that's something you'd consider.

@Whattodonowadays

Hi, don’t mean to sound like I am being horrible, this is just my opinion. I think you should just be honest and tell him that you have slept with someone else before you got serious. With the dates being so close together I think it’s going to be impossible to tell unless you do a dna test. If you do this on the quiet when the baby is born and then find out it’s not actually his, how is he going to feel then!! A lot more angry than he would be if you told him now. Obviously if your friend did it finish then it’s much more likely to be the other one but you never know really.

Hey don't worry you're not being horrible at all you're just sharing your opinion which you're entitled to.

It's just the likelihood of it being the other guys is very unlikely. I know theres a very very small chance it could be the other guys but it seems impossible when I compare it to how many times I slept with the other guy around that time. My cycle length is 26/27 days and if the NHS typically uses the average 28 day cycle i would have ovulated and conceived before then. Then again I will never really know. Our bodies work differently and we never really know when.

I've done my research on precum too and have used the withdrawel method in the past and have never had any issues. I think i'm just going to have to relax and wait until baby is here if I go from what my midwife has informed me. I don't want to be feeling stressed throughout the rest of the time I have left being pregnant.

@JuneySunshine

No problem.

I do think she has it wrong with early June and is confusing week 0 and week 2, just an innocent mistake.

From what you've said it sounds like the overwhelming likelihood is that the guy who you want to be the baby's dad is the father- you had a lot of sex and his sperm can then live for 5 days inside you.

Don't beat yourself up about the situation. It's just a case of deciding what's best for you now- if you're able to let things be or if you need to know for sure. I've seen other threads on here about DNA testing etc. if that's something you'd consider.

Yeah I just feel let down because she seen how upset and stressed I was about the entire situation.

Yeah I think I would know deep down if it wasn't his. It would be a completely different story if the opposite had happened with the other guy. I think once baby is here and if I have any doubts I will deal with it then.

I would say its who you assume is the baby's father.
I think your getting worked up because you slept with someone else so doubting it.
but it is best to come clean because it's better out now than it is when baby arrives.
For him and for you.

If I plug your dates in, it says you likely conceived around 20 June give or take a day or two.. so could theoretically be either. Hope it works out the way you want it to.