QuestionBased on my lmp, my due date suppose to be december 30(according to my doctor). On August 13th, i was 20 weeks 1 day, and measurements gave me a due date of December 25th. Two days ago, my doctor said i was measuring a little big for how far along i am. I know that there is some margin of error on ultrasounds, but is there anyway that it could be 6-8 weeks off. All of my dates match up to my boyfrieng being the father, but i'm worried because the three periods i had were closer together than usual and very light. Basically i just need to know the margin of error possible on a level 2 ultrasound if it measured a due date of december 25th.
Followup To
Question -
i am 22 weeks pregnant according to lmp on March 25. I bled on feb.4, march 1 and march.25. Could i have gotten pregnant before feb 4 and the ultrasoud gestation be wrong? When you bleed during early pregnancy (like during implantation or spotting) would that cause innacurate gestation in an ultrasound. I'm trying to figure out if i could be 29-30 weeks instead of 22, because this could cause problems with paternity if i could be.
Answer -
By now, you should have had your sonogram. If your last period started on March 25, you are now exactly 21weeks
0 days gestation. You did not mention what the calculation of the sonogram showed. The bleeding during the pregnancy has no effect on the dating by sonogram. If your last period started on March 25, then you would have ovulated around April 7 and could only have become pregnant if you had sex on April 6,7,8, or 9. That would agree with your last period being March 25 and a due date of January 31, 2005, and you would now be 20 weeks size. If the sonogram showed you to be 22 weeks, your last period would have started on March 19 and you would have conceived around March 31, April 1,2, or 3.
AnswerA sonogram performed at around 20 weeks has an error of + or - 14 days. If your last period started on March 25, you are due on December 31 (based on your dates) and you ovulated around April 7. You could have conceived ifyou had sex on April 6,7,8, or 9 (as I mentioned before). If the sonogram taken on August 13 showed a 20 week 1 day fetus, your due date is still December 25 (based on sonographic measurements). However, even if they calculated a due date of December 25, than your last period would have started on March 20, and on August 13 you should have been 20 week 5 days. That would mean that you ovulated on April 2, and could have conceived on April 1,2,3,or 4. There is no way that you could have conceived after April 9 and there is no way you can be larger than 22 weeks, at most. You certainly are not 6-7 weeks larger.
