Women's Health: Postpartum Community
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Avatar universal

Due Date Accuracy

I am pregnant and due to a previous ectopic, I have had 4 ultrasounds so far and I am 24 weeks along. When first asked by my practioner the first day of my last period, I explained that the "last" period in Feb. was extremely abnormal and very different from my normal periods. Not only was it almost 1 week early (although I am always off a few days) but the flow was very light and sort of on and off if you will. I remember wondering if everything was okay. Then, I did not have a period in March and later found out I was pregnant. Anyway, my practioner counted that Feb. period as the last period I had. Every untrasound that I have had has my due date around Nov. 20th. I can only assume that it really was a "real" period in Feb. and I conceived during ovulation later in the month of Feb. My question is how accurate are the unltrasounds. What are the chances that I am actually futher along, meaning I conceived during ovulation in January? I would hate to go into labor when I am not expecting it at all. Can I rest assure that I am due around Nov. 20th based on the ultrasounds that I have had? Are the ultrasound dates calculated freely or is information entered based on the last period? I am wondering what their accuracy is. I just cannot forget how different that "last" period was and I am worried because my doctor is using that one as a normal one. Thanks!
3 Responses
Avatar universal
With my second son I did not know when my last period was and they calculated his due date as Jan.5th.  I had him on Dec. 20th and with my first son I had fertility and new exactly when my last period was and his due date was Feb. 4th and I had him on Jan. 19th.  The ultrasounds are fairly accurate based on the measurements of the baby.  But the baby will come whenever it is ready.  I'm sure that the baby will come around the 20th of Nov. and that they have calculated by the measurements of the baby.  Best of luck
175662 tn?1282217256
With my first daughter I didn't know when I had concieved.  They dated my pregnancy and changed the date 4 times (from the end of October till the end of December.)  She was finally born 12/21/92.

With my 2nd daughter I again had irregular periods, so they used the u/s to date.  They gave me a date of August 16th.  I went into labor August 16th and she was born 8/17/97.  

I think it depends on the tech and how cooperative the baby is.
Avatar universal
Since you have had 4 ultrasounds I assume they are pretty accurate...assuming also you had them early in your pregnancy.

How far along were you "supposed to be" when you had the first one?  There is a big difference between 8-9 weeks, 10-11 weeks and even 12-13 weeks.

I've had 3 so far...7 1/2 weeks, 10 1/2 weeks and 12 weeks....and let me tell you there was a huge change from bean to baby.  With that, you wouldn't see a "bean" at 10 weeks...and by 12 weeks there would be a baby with arms and legs.  Soooo....I would say they are pretty accurate....they get less so specific further into your pregnancy.
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