How to tell if you're having a boy or a girl - signs your ultrasound reveals about the sex of your baby

When you're expecting a baby, the 20 week scan is incredibly important for many reasons.

Also called an anomaly scan, not only does it signal the halfway mark, but it's also crucial in checking your baby is developing as they should.

Parents-to-be also look forward to it because it's at this stage they can find out the sex of their child.

Of course, with no shortage of theories and old wives' tales out there, they may already have their suspicions.

Yet as much as you may think you can spot a gender clue in those grainy images, to the untrained eye, there's no way of telling.

Many parents look forward to the 20 weeks scan (Westend61)

But what is it sonographers look out for themselves?

Firstly, it's not always possible to tell the sex of your baby.

Baby's position may hinder this, as the sonographer may not be able to get the view they need to ascertain if you're carrying a boy or girl.

Some babies are exhibitionists, others are a little shyer.

A lot of tummy fat could also make it harder to see.

You can only be 100 per cent certain it's a boy (Getty)

Secondly, an absence of a penis does not necessarily mean you're having a girl.

If the ultrasound technician fails to find a penis, don't automatically assume the baby is a girl, warns VeryWellFamily.

At this stage in your baby's development, a penis and clitoris tend to be roughly the same size, so your sonographer will look for different things to determine the sex.

Turtle sign for a boy.

If it's a boy they're looking for, the ultrasound technician will look for something called the turtle sign.

This is when they can see the tip of the penis just about peeking out from behind the testicles.

With some babies, this is easier to see than others, so they'll also be looking out for other signs too.

An erect penis for a boy (unsurprisingly).

Yes, even from the earliest of ages, men have this functionality.

If this happens during the scan, it will show a very clear and defined penis.

Don't worry, it's normal, and they never grow out of it.

Hamburger sign for a girl.

As for signs you're having a girl, your sonographer will look out for three lines which show the external female genitalia, called the hamburger sign.