After a slip of the tongue prompted headlines declaring the sex of the former Kate Middleton's unborn baby, here's a look at some of age-old, but unproven techniques parents-to-be have used to predict what's coming.

Morning sickness

Little girls may not always be sweet -- nausea early in the pregnancy indicates a little girl, while a lack of first-trimester morning sickness points to a boy. This myth may offer another hint that Kate’s carrying a little girl, after she was hospitalized early on in her pregnancy for acute morning sickness.    

Swing a ring

Suspend and swing a wedding or engagement ring over a pregnant belly and take note of how it moves. If it swings side to side, it’s a boy, while a circular motion indicates it’s a girl.

How do you look?

Is a change in hormones causing acne breakouts? Is your hair thin and dull and your face swollen? If so, urban legend indicates you’re have a girl who is apparently stealing some of her mother’s beauty.

If you’re projecting a ‘pregnancy glow’, get ready for a boy.

The Drano test

While a pregnant woman should not handle Drano, the myth goes: If you pour some Drano into a pregnant woman’s urine and it turns green, brown, black or blue, it’s a boy. If it turns red or yellow or there’s no color change, it’s a girl.

Weight gain

Probably one of the most prominent folklore tales of a baby’s gender comes down to where a pregnant woman carries her weight. If she’s carrying the baby in front, it’s a boy. If the baby weight spaced all around her middle it’s a girl. 

If dad has put on a few pounds during a pregnancy, it’s another sign of a girl.

High or low?

This one can be done just by looking south: if an expectant mother is carrying high, break out the pink. If her bump is low, she’s carrying a boy.

The Mayan test

They may not have been right about the doomsday, but legend has it that the Mayans determined a baby's sex by looking at the mother's age at conception and the year of conception. If both are even or odd, it's a girl. If one's even and one's odd, it's a boy.

More traditional gender test

While the aforementioned tests generally have a 50 per cent success rate, doctors say an ultrasound is the most accurate way to determine a baby’s sex.

Typically ultrasounds at 18 to 20 weeks into the pregnancy can determined the baby’s sex and its accuracy depends on many factors including the age of the baby, the equipment used, the technician, and the cooperation of the baby.

Prince William and Kate had previously said they would not reveal the baby’s sex before its birth.