I had my first scan in Spain at about 13+4 and the doctor was able to tell the gender of my baby from the bone structure of the genitals area - he said he was about 96% certain.
I just read a thread from a women in France who said that same - that her doctor could tell the sex at 12 weeks, he said with 99% certainty in her case - I guess it depends on what position they are in as to the degree of certainty.
I get the impression that both these doctors are at the forefront of the profession in their countries, but I assume there are equally expert doctors here in the UK.
Does anyone have an experience in the UK of being told the sex early on? I realise the 'usual' expectation of finding out the gender is around 20 weeks. I just found the range quite intriguing and wondered about other peoples experiences.