A team of experts in Mount Sinai, Toronto conducted tests to see if some of the countless old wives' tales that have been used to predict gender for years actually do have some truth - in particular the effect of blood pressure.
Analysing more than 1,000 women trying for a baby, researchers followed them throughout their pregnancy, to delivery and through to clinical care.
Taking into account age, education, smoking, BMI, waist circumference, cholesterol levels and blood sugar levels, scientists found that systolic blood pressure before pregnancy was higher in women who went on to welcome boys, than those who had little girls.
In fact, those with highest readings had a 62 percent chance of having a boy.
The authors noted: “Indeed, higher maternal blood pressure before pregnancy emerged as an independent predictor of subsequently delivering a boy.”
However, Professor Adam Balen, chairman of the British Fertility Society told The Sun that it was "baffling" maternal blood pressure should have an influence on gender.
“I don’t think too much can be drawn from this study and it would have to be repeated in other populations.”