To ask for your help explaining this to my boyfriend?

[ufgh]

So, I'm trying to explain to DP about due dates and the fact they're calculated from your last period.
We know full well I conceived 2.5 weeks after that as we hadn't slept together for ages before that.
So now he's confused that we slept together and conceived say 12 weeks ago but baby is measuring 15 weeks.

How do I explain this?

Can you show him a menstruation cycle diagram and explain again thst all pregnancies are dated from beginning of last period but conception happens around ovulation?

I do hope the underlying message of this isn't that he's accusing you of cheating?

Is he a bit stupid ?

And why are you needing to expend so much energy "explaining" it to him ? What is his problem ?

You’ve made a mistake. The measurements are actually standard in the first trimester. If you baby is measuring 15 weeks then you must have conceived 15 weeks ago.

@Podemos I'm not sure, I hope not.

No , Boggles. If baby is messuring 15 weeks then she conceived (approx) 13 weeks ago although exact day of conception will depend on the length of yoir cycle.

If as above he is querying this due to thinking baby isn't his then you don't explain it, tell him talk to a GP, another adult or Google it. He needs to find it out for himself.
If it's not above and he just isn't aware then he probably isn't aware of a lot of pregnancy related things. Buy him a book. It will have all the info incl how to calculate due date.

Op, you do think he is questioning paternity don't you ?

It’s weird but that’s how it’s done. You’re usually 2 weeks pregnant when you conceive. There will be plenty of online sources to explain this.

Boggles are you OP's DP? [wink}

oops

I would just have my midwife explain how it works to him, she'll be able to explain technicalities to him without any emotion.
Dating is one of those things that in theory makes sense, but can be confusing.
It threw me because by my dates I'm a week behind what my midwife and first scan showed.

Sounds like you've explained it to him. Pregnancy is dated from the start of the last period. That's it. My friend had ivf. She knew the exact date and time that the eggs had been transferred. By which time she was officially 2 weeks pregnant.

He's still confused. He just isn't grasping that on the day you actually conceive, baby measures 2 weeks/you're 2 weeks pregnant!

Midwives have better things to do than explain simple concepts to hard of thinking men

He's also confused because he says he understands why they count it that way to begin with but surely after a scan it should show baby measuring to when it was conceived.

By that token, you too have better things to do

Point him to google and tell him to stfu

Has he form for controlling behaviour ?

@AnyFucker not even slightly!

What does it matter? Is he as obtuse about other things?

It is confusing. I knew the exact date of conception too but DP didn’t question the due date being 2 weeks later iyswim. I always thought they had my due date wrong as well, I hadn’t been having any periods so when I conceived it was all guess work as to my cycle. They gave me a due date but I actually think it was 1 week incorrect, she arrived 3 weeks early (4 weeks IMO) and was low birthweight which made me think I was right!
Anyway why is he questioning instead of just happy?

Maybe explain why. I think it’s because before scans the last time you were known not to be pregnant was end of last period and even once scanning became common I guess it took a while to have the stats to do dating by measurement. Also point him to online resources or get him to ask the midwife at your appointment. If he’s not listening to you he might take it from someone else. It’s not difficult to understand, sounds like he doesn’t want to understand.

*He just isn't grasping that on the day you actually conceive, baby measures 2 weeks/you're 2 weeks pregnant!

*
To be fair, it is a stupid system! I find it confusing too!

He needs to use Google and understand the info himself. You've told him the facts. Now he needs to study them and get his head round it.

He's still confused. He just isn't grasping that on the day you actually conceive, baby measures 2 weeks/you're 2 weeks pregnant!

Wait, what?

I am infertile and therefore not totally up to date on this shit, but surely on the day you conceive, the baby is like 1 day old?

@FuriousVexation exactly his words!

It’s the age of the egg.