However, not all hospitals will give parents-to-be the option to learn if they are expecting a girl or a boy, as it's not actually part of the National Screening Programme, says midwife Tracey Owen.
Your 20-week scan is a screening procedure to look at the structure of your baby, their bones and organs, and also find out your due date.
Owen advises parents-to-be to chat to each other before they go to this scan to find out in advance if you both want to find out the sex.
If the sonographer offers to tell you, you can then give them a thought-out answer.
"Remember, if the hospital does tell you even they may get it wrong sometimes," Owen adds. "It's not always 100%.
"Regardless if you find out or not, it's a great time to bond with your baby and realise what's growing inside you."
Watch the video above to hear all of Owen's advice.