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Conception date & ultrasound

If you measured farther along than your LMP when an ultrasound was done and the dr. used the ultrasound due date rather than the LMP due date, do you still count back 38 weeks to determine when conception may have occured? or 40 weeks?

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Asked by Anonymous at 10:22 AM on Mar. 28, 2009 in Pregnancy

Answers (4)
  • i say go with ur LMP... its probably most accurate if ur monthly friend is regular.
    According to my LMP, i concieved at the end of Jan. but everytime i went for an ultrasound the dr. would add on 4 wks. (idunno wht thats about) Anyway, according to the ultrasounds i was given due dates as early as sep. 25, I disagreed everytime i saw another dr. bt that was their story n they were sticking 2 it. I believed that i probably wouldnt deliver til Oct. Even still the latest they expected was Oct 14. I was right n they were wrong, my daughter was born OCt. 23... lol, who says i got pregnant in Dec???

    Answer by StarrCooKie at 10:36 AM on Mar. 28, 2009

  • mine isn't regular and the month i got pregnant it was 9 days late. so im pretty sure the ultrasound due date is more accurate. but i was just wondering when they give you a due date based on ultrasound do you still count back 38 weeks to determine when you conceived?

    Answer by Anonymous at 10:43 AM on Mar. 28, 2009

  • Unless you know the exact date you ovulated, it doesn't really matter. They will always go by your last menstrual period and/or the ultrasound date. They don't care about a conception date....especially if one is irregular because it is even harder to tell when you actually ovulated unless you only had sex one time that month.

    Answer by Anonymous at 10:46 AM on Mar. 28, 2009

  • The conception date is one date they never actually talk about because they can never know it for sure. Even if you had sex only once that month you might actually "conceive" two days later! They use dates they KNOW like your last menstrual period...even though generally speaking two of the weeks of pregnancy, you weren't actually pregnant at all. For me, it was easier to always focus on the due date rather than the number of weeks pregnant because of that. What is the difference what date you conceived anyway? Sort of water under the bridge....You could try asking the doctor that question, though.

    Answer by BJoan at 12:11 PM on Mar. 28, 2009

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