Several old wives’ tales suggest that morning sickness can offer a clue to the baby’s sex - and there might just be a grain of truth to it.

Severe morning sickness - which blighted both of the Duchess of Cambridge’s pregnancies - means that the mother is more likely to give birth to a girl.

Researchers analysed 1.7 million pregnancies and found that women who suffered from ‘hyperemesis gravidarum’ had lower odds of having a son.

Hyperemesis gravidarum strikes one in 100 pregnancies and is characterised by vomiting up to 50 times a day.

Lena Edlund of Columbia University in New York said that women with hyperemesis gravidarum gave birth to daughters 56% of the time.

‘Normally, slightly more boys than girls are born, we don’t quite know why that is,’ says Edlund.

The researchers say that it’s possible that the reason is that women with hyperemesis gravidarum are more likely to miscarry and that a male foetus is more likely to be lost than a female one.