Confusion about dates and longer cycles

[Em_325]

I know this should be simple to work out but I have gotten myself all confused

According to my LMP i would be 5 weeks and 6 days today but as i know that is based on a 28 day cycle and I have 32 day cycles should I subtract 4 days and say I am 5 weeks and 2 days? I have been going with the subtraction of 4 days but my Doctor keeps saying no it is counted from LMP regardless of cycle lengths but I cant see how this could be accurate for people with longer cycles.

[Teeki]

Your doctor is right on this one, they always go by lmp, whether it's correct or not. Have you had a dating scan? If you're certain the edd they've given you is wrong due to your longer cycles, I'd be requesting a dating scan and asking that they go by that edd.

Good luck, and congratulations on your pregnancy!

[TeniBear]

No, that's wrong. At first they would go by LMP, but once you explain your long cycles they should believe you and/or send you for a dating scan. As an example, if I'd managed to get pregnant on my longest cycle last year and they insisted on using LMP, my "EDD" would have been about a month after I found out I was pregnant.

[Teeki]

No, that's wrong. At first they would go by LMP, but once you explain your long cycles they should believe you and/or send you for a dating scan. As an example, if I'd managed to get pregnant on my longest cycle last year and they insisted on using LMP, my "EDD" would have been about a month after I found out I was pregnant.

Having not dealt with this personally, if you didn't get a dating scan would the doctor take your word that the edd is wrong? Or should they automatically refer for a dating scan?

[Em_325]

No, that's wrong. At first they would go by LMP, but once you explain your long cycles they should believe you and/or send you for a dating scan. As an example, if I'd managed to get pregnant on my longest cycle last year and they insisted on using LMP, my "EDD" would have been about a month after I found out I was pregnant.

Thats what I thought too Teni. I know I am only talking about 4 days here but for people with loooooong cycles how could it possibly be accurate?

I should add that it is not the EDD I am confused about (there are a heap of due date calculators that take long cycles into account so I am happy with that) it is how many days pregnant I actually say I am. I know technically they count it from the LMP but I dont want to say I am xx when I am really 4 days behind as I ovulated etc 4 days later. I have a referral for a dating scan but that is actually what prompted me to ask this question as given my previous experience I dont want to be told I am measuring behind if it would be due to having a slightly longer than average cycle (I hope that makes sense)

[Jaycee]

I would definitely request a dating scan if my cycles were longer than average!

[PumpkinZulu]

Do you know when you ovulated? I have incredibly irregular cycles, I have either said I didn't know when my lmp was, or counted back 14 days from my ovulation and given that as my lmp.

[Pholi]

... I dont want to be told I am measuring behind if it would be due to having a slightly longer than average cycle (I hope that makes sense)

I think that since it is specifically a dating scan, ie, a scan to determine how pg you actually are, whatever the scan says will be taken as the date. When they ask when your lmp was, say it was 'around the ...th of February' or what ever, and that you have long cycles. if they ask how many weeks along you think you are, just be honest - say that you reckon you're X weeks and days, cos you have long cycles.

[TeniBear]

Yeah, I'd probably say you don't know exactly when my last period was or lie about it - "it was around [date that fits their LMP estimation], I think, should I have a dating scan?"

[Eenee]

Yeah it's stupid how they work it. That's why I told them this time I didn't know when my LMP was. As it was over 12weeks ago but I'm only about 8weeks. You think they'd get up with the times. That's why it's easier just to lie about your LMP and bring the date forward a bit.

[Teeki]

I guess that's what happened with mine. I told the gp I definitely had af 25/12, but may have had one 16/01. I just asked outright for a dating scan.

[HomeStyleMumma]

If you have a good understanding of your body and cycle length etc then any half decent doctor SHOULD listen to you and at the very least use that to help gauge edd. Sadly this is very often not the case and many drs especially those that don't regularly deal with pg beyond writing the initial referral to ob/mw will just insist on going by lmp unless you REALLY put your foot down.
In my experience because I've always been able to explain in detail my circumstances and logic behind NOT using lmp to determine edd I haven't had a problem getting the edd that I know to be true, but I have a good relationship with my gps and they are willing to listen to me.
For eg if I didn't know when I Od with dd1 my lmp would've been a whole year earlier because I didn't have one between those to pregnancies lol. And this time not only would it have been impossible to get pg when the 'normal' time would be (dh was away for a wk either side of O) but it would also put my edd about 4 days out like you. Which in my case could mean a lot of unnecessary fussing and attempted intervention should I birth this baby early like previous babies. (my last cycle was actually a fairly average length I think wouldve been 27days or something but I didnt O until cd16 (very early for me) and only have an 11d luteal phase so still doesn't fit into to normal as normal is considered)
If it were me I'd tell them what date you Od and they can work back two wks from there to get the so called all important lmp

[Cassius2]

i always inform them of my 'special length' cycles and they adjust for me...that way i also get to avoid the dating scan.

[Taryn]

That's a good idea PZ. I'm going to do that next time.

I also have a long cycle, a bit longer than you. And when I had my first ob appointment they were going by my lmp then he did a dating scan because I told him when I ovulated etc & my due date was pushed.

It's silly that they just go by lmp I reckon.

Good luck

[Taryn]

That's a good idea PZ. I'm going to do that next time.

I also have a long cycle, a bit longer than you. And when I had my first ob appointment they were going by my lmp then he did a dating scan because I told him when I ovulated etc & my due date was pushed.

It's silly that they just go by lmp I reckon.

Good luck

[onthefly]

I would just calculate my own LMP based on ovulation date and tell them that at the outset, to avoid all the kerfuffle

[Heaven]

Yep, for number 2 I did the same as PZ and just lied. They wouldn't believe me the first time, apparently they knew my body better than me and they couldn't get their head around the fact that I ovulated later than the 'perfect' time. Soooo frustrating!!

[Em_325]

Thanks for the responses everyone! I will add 4 days on to my LMP and stick with being 5+2 today. This is only my GP i have been dealing with so when I see my OB I'll give him the amended LMP date and hopefully the scan will correspond with that.