The new study may give credence to common belief that women who want a boy should eat more red meat, salty snacks and fish, but should plump for vegetables, chocolates and sweets if they want a girl. However, nutritionists advise that all pregnant mums should eat a well-rounded healthy diet and avoid having too much sugar.
The scientists, who carried out the research at the University of Pretoria in South Africa, found that mice with low blood-sugar levels – a good indicator of a sugar-rich diet – produce more female than male offspring.
Researchers gave 20 female mice a steroid, dexamethasone, which kept their blood-sugar levels low. The sex of their litters was then compared with that of 20 mice on a regular diet.
Those eating normally produced offspring that were 53% male. But those on the steroid produced litters that were only 41% male.
The results showed that, in mice at least, a diet that is high in sugar can lead to more female offspring and the researchers say the same could be true in humans.
But Elissa Cameron, who led the project, said it was unclear how blood-sugar levels affect the sex of the offspring, though previous research suggests food may affect the environment in the womb, creating conditions which are more favourable to male or female sperm.