How can one predict baby gender from ultrasound report at 12 weeks?

Depends on variables. Although the parts may be present it is difficult to be accurate on gender assessment at 12 weeks.In the hands of a skilled tech with a high resolution probe this can sometimes be suggestive.However, it is more reliable around 18-20 wks. Even then, I have seen folks who decorated a nursery based on us have to repaint when baby delivered.