If traveling to the hospital is a problem and you don't want the inconvenience then you could ring your midwife to discuss it with her again.

how accurate are dating scans at 17 weeks-11

I thought this seemed a little late and I knew I couldn't have conceived on a wednesday anyway as my OH works away (but I presume they have a couple of days either way for margin of error?

) Anyway every time MW measures my fundal height it's always a couple of cm bigger than average.

One thing to remember is that conception rarely happens the very day you have sex. I was going to post with a short comment but figured just in case I didn't remember correctly I should look it up. Quite often a good method is to have sex a couple days before ovulation as well as the day of due to timing issues.

So basically all I'm trying to say is the sex that caused conception could have taken place a few days before ovulation.

Transvaginal ultrasound is safe and commonly performed during all stages of pregnancy, including the first trimester. Transabdominal ultrasound involves scanning through your lower abdomen.

A small amount of ultrasound gel is put on the skin of the lower abdomen, with the ultrasound probe then scanning through this gel.

I will just have to be prepared incase baby happens to be early then !

all they're doing really at a dating scan is measuring baby, which can't be 100% accurate, I'm sure, and if adults and kids and even newborns are all different sizes are all 12 week old foetuses really exactly the same size? Both me and my husband and both sets of parents are really small so expected a small baby therefore small at scan therefore to measure as a later date than she might actually be (based on no scientific research whatsoever, I might add!

For many women, especially after 8 weeks gestation, sufficient information about the baby may be obtained with transabdominal ultrasound only.