Kate Middleton and Prince William
Kate Middleton's baby bump doesn't determine the gender of her third baby. Pictured: Prince William and Middleton attend the EE British Academy Film Awards (BAFTA) held at Royal Albert Hall on Feb. 18, 2018 in London. Getty Images/Jeff Spicer

The gender of Kate Middleton and Prince William's third baby remains unknown.

There are rumors that Middleton and Prince William are expecting a girl because her bump is "high and wide." When the Duchess of Cambridge was expecting Prince George her bump was lower. However, according to an expert, there is no way to tell the gender of a baby based on the mother's bump.

"Kate Middleton's baby bump has nothing to do with the gender of her third baby with Prince William," Dr. Sherry A. Ross told Sunday Express. "There are no truths to any of these old wives' tales I've come across during my 25 years practicing as an ob-gyn."

According to Ross, the size and shape of a baby bump have a lot to do with the mother's size and shape but not with the baby. For instance, a tall woman tends to have smaller baby bumps than a short woman.

"Because they tend to have a larger midsection, taller women tend to stick out less and show later than shorter women," Ross explained. Meanwhile, shorter women are more likely to have a low bump.

Although the gender of Prince William and Middleton's upcoming baby is still a secret, many are convinced that they are having a girl. Most of the royal fans are betting on a baby girl name for the Duke and Duchess of Cambridge's third child.

Initially, the leading name was Alice, but this changed after a couple of weeks. The number one choice recently is Mary with odds 7-1.

"We can't quite put our finger on the link between Mary and the North West, but the overwhelming support means we have a new favourite in the royal baby name market," Jessica Bridge of Ladbrokes Betting Agency said.

"Punters are convinced the Duke and Duchess are expecting another little girl, and obviously it would be a lovely touch to honour Her Majesty's Grandmother, but it will be interesting to see if any boys' names are backed over the coming weeks before the birth," Bridge continued.

On the other hand, the most popular name for a boy is Albert with odds 12-1. Other popular choices in case Middleton and Prince William are having another little prince are Arthur, Frederick, Henry and James.