Could my Ultrasound be this OFF?

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Last seen: 1 year 5 months ago
Joined: 03/16/15
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Could my Ultrasound be this OFF?

I have been given two different due dates in the beginning of my pregnancy. Both of my ultrasounds were performed in my first trimester as dating ultrasound because I was unsure of LMP and I'm usually pretty irregular.

I had sex with #1 on June 8-9 and sometime in late June I remember getting a period.
I never had sex with that person again. Only my boyfriend from that point on. I found out I was pregnant late August and the first doctor I went to was at a free clinic and they gave me a Due date of April 21st but a few weeks later at my actual OB they gave me a due date of April 15th....
When did I conceive? Is #1 even a possibility??

WHY two different dates for a first trimester dating scan?? Can it be even further off?

MissyJ's picture
Last seen: 2 months 1 day ago
Joined: 01/31/02
Posts: 3289

# 1 is extremely unlikely unless you were mistaken and did have sex with him in July. With either due date your ovulation date would have been in July. For the April 15th due date, ovulation would have been on / around July 23rd. For the April 21st due date, ovulation would have been on / around July 29th.

Dating ultrasounds can vary in the first trimester due to a few different reasons. #1 both should have been transvaginal. The type / age of equipment being used and the experience of the tech also may play a factor. You can keep in mind that due dates are solely estimates that may vary +/- a few days at this (dating) stage. Typically, the first ultrasound would be considered more accurate *unless* you believe that the tech / equipment were better at the regular OB/GYN (probably.)

Hopefully your main relief will be in knowing that you should have conceived with your current boyfriend. Please come back and join your birth club to share the remainder of your journey.

All the best,