Determining due date.

[BronzedGoddess]

Hi ladies. Yesterday after I had my ultrasound they changed my due date from the 5th of May to the 30th of May, but I am 100% sure of the first day of my last period becuase I always mark it on a calendar. Is the ultrasound more accurate than going by the date of your last period? Thanks everyone.
Carolyn

 

[rockette]

Iwould think the ultrasound is more accurate. The closer you ovulated to day 14 the more accurate the LMP(last period) date would be since that's what doctors base your gestation on. The further you ovulated from day 14 the less accurate that date would be. For instance, if you ovulated on day 30 instead of day 14 then based on your LMP your baby may measure a little smaller than normal and so the doctor would probbaly need to adjust the due date to account for that.

In the end though, it's al1 an approximation. No one knows for sure.

Hope this makes since.
Valerie

 

[amynicole]

Valerie is right. Also, sonogram due dates are only accurate if they are taken before 20 weeks. Most accurate in first trimester. My first 2 children were born on the due date of the sonogram! Isn't that funny. The sonogram and my due date based on my period were always a few weeks off and both baby number one and two were born on the songram date. Baby number 3 was also born on the songram date but since he was induced we will never know if that would have been the case.

the baby will come when he/she is ready!!

 

[mogambo]

I learned while pregnant that the sonogram due date used the "day the baby reaches the average size for a newborn". That to me seems arbitrary and silly compared to the estimated date of conception if you know it. I mean, what if you have a larger than average baby? My sonogram due date was Jan 5, my estimate based on periods was Jan 13. My daughter was born Jan 19 (18 years ago) so if they used their dates they would have induced me. Instead I ignored their dates and did a home birth. Logan weighed 8 1/2 pounds at birth. So, use the sonogram information, but take it with a grain of salt.

 

[BronzedGoddess]

Thanks everyone for your replies. My heart tells me that my son is going to come before his new due date. That's just my motherly instinct. Thanks again.

 

[Storm2]

I don't know how accurate this is, but I have read and have also been told by some nurses, that an u/s done during the last half of pregnancy, is not as accurate, as those that are done during the first half. Judging from your original due date I would say you are around 25.5 weeks. Is that right?? Did you have an earlier u/s, and if so when did they date the pregnancy then? Also, do you know when you ovulated? How soon after your last period did you get a positive on a pregnancy test? Do you remember the date? How many weeks were you when your doctor first heard the baby's heartbeat with a doppler? I was told with one of my pregnancies that I wasn't due until the end of April, (my EDD was originally April 1), I knew this couldn't be true, because according to the u/s, it would have been impossible to have gotten a positive on my home pregnancy test, when I did. Sure enough, my baby was born March 24th. I did have an earlier u/s and it had my dates as being correct. My doctor never changed my original due date. HTH

 

[brendainwa]

As has been mentioned, an ultrasound done this late in pregnancy is not that accurate for deciding on a due date. That said, be glad the date was changed for later rather than sooner. If they are right and you are due later, then your baby will be given the time to develop and you can go into labor on your own rather than being induced. If they had moved the date up so you were "due" earlier, you would be taking a big risk that you would go past the new due date and possibly be induced with an early baby. It's happened before.... I gently suggest that you prepare physically for the little one to come early, but prepare mentally for him/her to come later. I have done the 10 days of waiting because we thought he would come earlier--longest 1.5 weeks of my life. Now I always assume the baby will be late so I can be pleasantly suprised

If you know when you conceived, the date figured from that day will be more accurate than the date figured from first day of last period. I'm very regular but have long cycles. With my youngest son, my LDMP was Oct 31, giving me a due date of Aug 7. I conceived at around Nov 25-26, which made my due date Aug 17. That's a 10 day diference! I then learned that pregancy averages longer than 40 weeks (41 wks and 1 day), my midwife and I changed the due date to Aug 19 or so. He was born Aug 21, almost right on time. If I would have gone with the first date he would have probably been induced and been a little early.

Sorry this got to be long--hope something was helpful,
Brenda