Expectant mothers are asking strangers to predict their baby’s sex in new online phenomenon

Fast-growing worldwide trend sees explosion in dedicated online forums using esoteric theory to guess gender

Expectant mothers are asking strangers to guess their baby’s sex by posting scan pictures online, in an obscure new internet craze.

Traditional medical scans cannot determine whether a baby is male or female until 20 weeks.

But some experts think it is possible to predict the foetus’ sex at 12 weeks, by analysing the skull shape and nub area between the legs.

Boys predominately have squarer chins, a chunkier skull shape and more pronounced brow ridge, whereas girl’s skulls have a smaller brow ridge and more pointed chins.

Babies with a nub – or genital tubercle – angled at greater than 30 degrees are likely to be boys, while girls’ nubs sits below 30 degrees.

The growing worldwide trend has seen a number of dedicated online nub and skull forums spring up, where medics guess the infant’s sex.

“The nub and skull theory is the fastest-growing gender prediction technique simply because it is so social," said Lisa Lum, a gender expert at parenting website Channel Mum, which commissioned a study into the craze.

"While no non-medical technique is 100 per cent accurate, it is fun and brings people together, which is exactly what children should do at all ages.”

The theory claims boys have square chins, a chunkier skull shape and more pronounced brow ridge whereas girl’s skulls have a smaller brow ridge and more pointed chins.

The most popular method remains asking at the 20-week scan with 63 per cent of mothers questioning medical staff on their child’s sex. Also fashionable is the Chinese gender prediction calendar which guesses the sex based on the date couples conceive and is tried by over half of mothers (57 per cent).

A further 48 per cent try to work out of they are having a girl or a boy by the size and shape of their bump and 45 per cent use the heart rate theory which claims a foetus’ heartbeat above 140 beats per minute is more likely to be a girl.

Meanwhile, 44 per cent analysed their food cravings and 30 per cent tried an old wives tale of dangling a ring on a piece of string above the bump, with a circling ring indicating a girl and side-to-side movement meaning a boy.

One-in-five even tried to guess their baby’s sex from the amount of morning sickness they suffered, with worse sickness believed to show a baby girl.

SWNS