(Closed) Confused about changing due date!

posted 5 years ago in Pregnancy
Post # 3
Member
5655 posts
Bee Keeper
  • Wedding: April 2011

Early u/s are the most accurate for dating. Once you hit 2nd trimester they aren’t…… Personally I would *always* be happy accepting a new later edd just b/c I know how doctors get itchin’ for inductions when they get close &/or are passed. lol

Post # 4
Member
1151 posts
Bumble bee
  • Wedding: March 2015

@Sunshine09:  Another bee posted something very similar and I’ve heard this quite a few times but definitely go with the first (later) date, that will be the most accurate. Sometimes there is a tendancy to get excited if the baby is slightly larger and predict a sooner due date – reality is the baby is just a little bigger at that scan (it may continue to stay a little bigger but that doesn’t mean it will come early!) Go with the first date 🙂

Post # 5
Member
452 posts
Helper bee
  • Wedding: May 2013

The most accurate way (if you have regular cycles) is the first day of your last period so you can calculate from that. US are not as accurate as we want to believe and are (should be) used for mostly when people don’t know when their last period began.  So was 12/23 the FIRST day of your last period or the last day?

Post # 6
Member
1622 posts
Bumble bee
  • Wedding: September 2012

@memorialbride13:  The LMP is not always the most accurate way to date a pregnancy.  First, the woman’s cycle needs to be regular and second, she needs to know the first day of her LMP.  Most health care providers I know put the LMP into the wheel and spin to find the EDB.  This is inaccurate because it doesn’t account for cycle length.  Naegle’s rule (LMP + 7 days – 3 months) is based on a 28 day cycle and needs to be adjusted for shorter or longer cycles.  Furthermore, some women ovulate twice a month, some women ovulate day 16 of a 28 day cycle, etc.  A first trimester ultrasound based on crown-rump length is accurate to 3-5 days.

@Sunshine09:  As the PP asked, what was the first day of your LMP and how long were your cycles, and were they regular?  A 28 day cycle would give you a due date of Sept. 30.  Then, the first ultrasound you had, thinking you were 12 weeks, said the baby was measuring 13 weeks….do you know if this was based on crown rump length or biparietal diameter or composite measurements? (bit complex, I know…just asking in case they told you)

It’s frustrating to have your due date changed.  I say to women all the time that solidifying the most accurate due date possible as early as possible is one of the best things we can do to avoid unnecessary interventions.

Post # 7
Member
1081 posts
Bumble bee
  • Wedding: June 2012

I was tracking my cycle by charting/temping/using OPKs, so I am pretty sure about when I ovulated at least within a few days.  My LMP was 12/11 but I didn’t ovulate until CD20…so my OB is all, “you’re due date is September 18th!” and I know from charting it is actually September 22…makes me wish I would have just told them my last period started on 12/16 instead of 12/11.  If your last period STARTED on 12/23, a 9/22 due date would mean that you would have had to ovulate on about CD7, which is pretty darn early (although not impossible).  I would say the later due date is probably the more accurate one anyways, and I agree with PP that you would want to take a later due date over an earlier one if nothing else but to avoid being induced because they think you are too far past your due date (I have heard inductions are WAY more painful contractions than natural…gahhh I want to avoid being induced so badly).  In all reality, it doesn’t matter TOO much, though, being different by a week is not that much of being different if that makes sense. Haha…either way for both of our sakes, let’s hope our babies decide to be natural September babies and not induced-September babies or October babies!!!! 😉

Post # 8
Member
1096 posts
Bumble bee
  • Wedding: June 2011

@cdncinnamongirl:  +1

I do not have a 28 day cycle so using my LMP is not going to be accurate. My cycle is 32 days and I was using the clearblue easy fertility monitor so I know my peak days were days 20 and 21. The prenatal nurse agreed with me but we’re keeping both options open until my first u/s. They like to do the first u/s at 8 weeks and we are going to do it on April 23 which is 8 weeks from my LMP but that’s with both of us knowing that I may only be 7 weeks at the u/s. The heart should still be beating at 7 weeks, my best friend was actually going to be OOT at 8 weeks so they did her u/s at 7 weeks and the heart was beating. 

Post # 10
Member
1622 posts
Bumble bee
  • Wedding: September 2012

@Sunshine09:  LMP of Dec. 23+31 day cycle = EDB October 2 (NOT Sept. 29 or22!).  CRL of 67mm = gestational age of 13 weeks.  Now, the standard where I practice is that if the due date by LMP and CRL differ by more than 5 days, we take the CRL since that is considered to be most accurate. Babies grow on a very specific blueprint until 12 weeks, which gives a highly accurate EDB when the CRL is used.

I’d have to know what the date of the ultrasound was to tell if it agrees or disagrees with an EDB of Oct. 2.

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