how accurate are early ultrasound measurements ? i’ve been measuring ahead at both ultrasounds. for my first one, based off my lmp i should’ve been 5 weeks 4 days, but i actually ended up measuring 5 weeks 6 days, then at my next one 3 days later i was measuring 6 weeks 3 days when it should’ve been 6 weeks 2 days. i usually have longer cycles like 30+ days so i honestly thought i would measure behind if anything.