Boy or girl

Harshita
I went for my 13 week ultrasound and the lady said she was certain and 95% sure it was a boy but today I went for my 20 week ultrasound and the lady said its a girl ... I am so confused ...  Has anyone every had a 13 week ultrasound and they said a boy and it turned out to be a girl when you went back at the 20 week ultrasound? Thank you for reading and have a good day