(Closed) Due date calculator

posted 7 years ago in Pregnancy
Post # 3
Member
1263 posts
Bumble bee
  • Wedding: September 2009

Most doctors calculate due date from the 1st day of your last period – so, technically by the time you actually get pregnant (around day 12-14 of your cycle, you are considered 2 weeks pregnant.  At your first ultrasound your doctor will be able to date your pregnancy to figure out how far along you are.

The thing is you might have had unprotected sex on 12/23, but you may not have ovulated until 12/27 or 12/28 (12 or 13 days into your cycle).  In fact, it’s unlikely that you ovulated on 12/23 (9 days into your cycle).  Sperm can live for up to 5 days so it’s likely that the 12/23 guys lived for a few days and you actually got pregnant a few days later.  

Congrats!

Post # 4
Member
2142 posts
Buzzing bee
  • Wedding: August 2010

Your due date is calculated on the first day of your last menstrual period. So technically if you conceive that cycle even before conception you are already pregnant by the due date/how long you are pregnant.

I agree, I think it’s weird! Whoever thought of this system is wonky. 😀

Post # 5
Member
5654 posts
Bee Keeper
  • Wedding: April 2011

It’s right for me….. I used my LMP and the day I ovulated (and 2 days after)

I believe that the day you BD isn’t the most accurate date b/c it can take 1-5 days to actually conceive depending on when you ovulate. I think.

Post # 7
Member
9053 posts
Buzzing Beekeeper
  • Wedding: June 2010

I agree with the above posters.  40 weeks of pregnancy is calculated from the start of your last period before becoming pregnant.  Which is usually roughly two weeks.  So, you kind of get two of those weeks for “free”.

Post # 8
Member
5654 posts
Bee Keeper
  • Wedding: April 2011

@bride21:  Idk why does it like that with your dates… must be a glitch b/c putting in my dates of LMP & then conception date give me exactly what we got from my midwife.

Post # 9
Member
1263 posts
Bumble bee
  • Wedding: September 2009

I think your conception due date coming up so much earlier than your LMP due date becuase you are saying you conceived 9 days after the first day of your last period…most women don’t conceive until 14 days after the first day of your last period, making you due a whole week earlier.  The only real way to know your due date is by ultrasound.

Are you putting in the FIRST day of your last period?  Ie, the day it began?

Post # 10
Member
71 posts
Worker bee
  • Wedding: May 2010

The normal calculator based on LMP assumes conception occured 14 days after the first day of your LMP. That would put conception around 12/29 vs. your estimated 12/23 and why it says you are not as as far along.

It is possible that either you ovulated early or the sperm survived for a few days or most likely a combination of both. It certainly is possible that you ovulated on CD 9 – I charted and used opk’s which both confirmed I ovulated around CD 8. Either way, the doctor should be able to give you an estimated due date when you have your first appointment or ultrasound. They based my first appointment on my LMP so I will not be going until I’m around 10 weeks by my calculations.

Post # 11
Member
494 posts
Helper bee
  • Wedding: November 2011

That calculator is only one day off of my due date of August 23rd. As others have said, it goes off of LMP and 28 day cycles. Other due date calculators use cycle length as well. The What to Expect one says that I’m 10 weeks pregnant when I’m more like 9w2d.

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