Yet science and folklore both give us clues that suggest Prince William and Kate Middleton will have a girl.
For starters, Kate Middleton’s debilitating morning sickness, hyperemesis gravidarum, is more commonly found among women expecting girls.
And her slim build may also hint at a royal daughter. A 2008 study at the University of Exeter showed women who consumed lower-calorie diets were more likely to have girls because female foetuses can survive on fewer nutrients.
Then William’s occupation as an RAF search-and-rescue pilot could also play its part. An American study found pilots had an 80% chance of having girl babies.
One theory is that exposure to radiation on planes reduces the number of sperm carrying male chromosomes, but sperm carrying hardier female chromosomes are unaffected.
And if Kate Middleton is spotted leaving a Kensington dermatologist, it’s odds-on for a daughter.
French researchers found that mothers who suffered acne while pregnant were 90% more likely to give birth to a girl due to excess levels of the female hormone oestrogen.
On the other hand, there may be some truth in the idea that women who suffer cold feet will have a son.
Cold feet are a symptom of poor circulation – and German scientists have found that this condition during pregnancy is often experienced among women expecting boys, though they haven’t yet been able to explain why.
If all else fails, there is one final method of prediction: ask the Duchess whether she thinks she is expecting a boy or a girl.
According to scientists from Arizona, women’s intuition is the most accurate gender predictor of all.
Asked to guess the sex of their child, mothers-to-be are correct 70% of the time.