Heart rate girl vs boy

Nicole

Had my ultra sound the other day, 8w4d (measuring ahead at exactly 9w) didn’t get to hear the heartbeat but doc said it was around 176. Everyone who knows is saying it’s a girl, how true is this theory that the faster the heart rate it’s a girl? I’m happy with either gender, it’s my first baby and I’m just so excited! But everyone is convinced it’s a girl based on the heart rate. ❤️