Ultrasound dating accuracy early
I had a dating ultrasound early on which put my EDD at June 5, making me 31 weeks. I have to go back in 2 weeks (just went in yesterday) and she said they would put me on some monitors to check who knows what.
They resumed when DS #2 was 16 months..they would only come every 6 or 7 weeks. I had no reason to think i was pregnant until I started feeling sick..sore breasts! The longer you wait the less accurate an ultrasound is for dates. I had one at 7.5 weeks and it matched EXACTLY to my date of conception.
You might be able to guess based on your own and dad's birth weight but if you're at the opposite ends of the scale it is still going to be hard to guess.
Don't stress about it though, trust your body and baby to get the timing right.
Low and behold my beautiful baby girl was born naturally on April 23 - just 4 days before my LMP date.
So that's my story and that's why I am going by LMP date for me.