How to know in 20 week pregnancy boy or girl?

Get an Ultrasound: At 20 weeks, it is usually possible to see if your baby is a boy or a girl by ultrasound. Sometimes a baby will keep their legs crossed and prevent visualization of the genitalia but if the ultrasound is repeated in a few weeks you can see it. There is a common belief that if the fetal heartbeat is fast (>140) its a girl and if it is low (.