don't forget to ask where to umbilical cords are so we can see if that whole gender prediction thing is right!
Found it!
The article said its all in the location of the placenta -- 97.2 percent of boys had their placenta on the right side of the uterus at that 6 week ultrasound, and 97.5 percent of girls had theirs on the left. Crazy, isn't it? According to their study, this method should be considered "highly reliable" in determining gender within the first few weeks of pregnancy.
Ohh and apparently if your first ultrasound was transabdominal, the image is flipped, so you'd reverse the sides.