Anyone else confused by the due date system?

[CassieSims]

So I just went to the doctor to confirm my pregnancy! She gave me the proof of pregnancy letter and all that, told me what I should and shouldn't do while in Hawaii next week. And then told me my due date was March 15th.

Uh... wait. I definitely conceived on June 22nd... I should only be 3 weeks and 5 days pregnant. but according to their system I'm 5 weeks and 5 days pregnant! I understand they calculate from the day of the last menstrual cycle but I just don't see how that makes any sense!

 

[AMAS86]

They will go by your lmp. until you have a dating scan

 

[IrishTwins]

it doesnt really make sense..

Apparently its done that way because years ago it was the only way for women to keep track of their pregnancies..

I have the same DD as you and know date of conception beyond a doubt but still am stuck with being 5+weeks



needless to say the 2 weeks is included in the 40 week total

 

[londonangel]

They do it that way because it will provide an approximate due date for those of us who don't have a clue when we ovulate ;-) They can't actually use my LMP to track as my cycles are so long. I was shocked yesterday though as doctor and I decided to date my pregnancy at 4 weeks from the date I tested (based solely on the fact that the pregnancy test came up the colour it would be if you test around your period) and when I had my dating scan yesterday it exactly matched, to the day. I am a bit disappointed really as thought I must be a few days ahead, surely?! Nope!

My last LMP was 24th March by the way but I'm actually 12 weeks pregnant today (!).

For women with normal cycles the LMP is a pretty good indicator though and you get a better idea at the scan.

 

[carlyjade86]

It doesn't really matter in the grand scheme of things... The 40wks include the 2 extra weeks, and that baby will come when it's ready - be it early or late! I didn't know my O with DS and he came on his EDD and I didn't confirm O with DD but knew the only time we'd BD'd and she came at 40+2. My dating scans were always spot on to the date I had been given - and it sounds much nicer being 5 weeks pregnant right now than 3! Lol x

 

[lynnikins]

its just the way they always have done things, using the system that is in place pregnancy is assumed as 40wks from the first day of your last period of course it works out different from O date or Implantation date but this is what is used and always has been.

 

[SpringOrchid]

I have a question too! You know when you go on these sites that say "by week 7 your baby's heart will have begun beating..." etc? Are they referring to week 7 according to LMP or according to conception date?

It is very confusing!

I know my conception date and was told to book my first antenatal appointment when i'm 8 weeks along. Again, do i book when 8 weeks according to LMP? If you're 12 weeks by LMP when you have your first scan, wouldn't they be alarmed when the baby was measuring small because O day wasn't actually until CD17?

 

[carlyjade86]

Always LMP. Always goes from then assuming everyone has a usual 28day cycle. So when you go for your 12 week scan, your baby will be 12wks from you LMP so that's exactly what they would expect to see. If u went from your Conception, when you have a scan they'd date you as 14wks - if u get me?

 

[SpringOrchid]

Always LMP. Always goes from then assuming everyone has a usual 28day cycle. So when you go for your 12 week scan, your baby will be 12wks from you LMP so that's exactly what they would expect to see. If u went from your Conception, when you have a scan they'd date you as 14wks - if u get me?

Thanks! That's very helpful.