My first was a girl and it took a while for them to be sure. This one is a boy and he isn't shy about it
Mine wouldn't show her stuff. They told me they were sure it was a boy,then the next month they said they were sure it was a girl. I felt like our baby was a girl from the start though.
I've known a few ppl (mom, SIL,step mom, coworker) whose babies didn't show their stuff at the anatomy ultrasounds, each of these women had girls.