how accurate is a ultrasound determining age?

[bj512]

i have a girl saying she's pregnant and its mine,today  she went for an ultrasound, blood test, etc. and was told she is 6 weeks pregnant, i was with her 8 and a half weeks ago, can these ultrasounds be out or? her due date is the 31 july i was with her on the 8 october

[LosingMyMindInGA]

First trimester ultrasounds are usually pretty accurate.  With the timeline being so close together, the only real way to know would be to have a paternity test done when the child is born.

[diamondintherough79]

Ultrasounds can be off from 1-2 weeks. If it was a dating scan they do a measurment of the fetus and go by there, Hence, why its isnt completely accurate.
Its still highly likely this child is yours, get a DNA test to be certain

[mm22732]

to be honest i would of thought if baby was yours then it would be bout 15th of july to be fair it seems to be it two weeks out. i would say dna test when baby born would be good