WOMEN could increase their chances of having a baby boy by upping their calorie intake when trying to get pregnant, research revealed yesterday.
Eating a daily bowl of cereal was also linked to having sons.
The study found that women with the highest calorie intake before conception were more likely to have a boy than women with a lighter diet.
The researchers, from Oxford and Exeter u
niversities, said the results suggested that the dieting habits of women in the western world could help explain the falling male birthrate.
The latest research, published in the journal Proceedings of the Royal Society B, looked at 740 first-time mothers in the UK.
The women were asked to keep records of their eating habits before and during the early stages of pregnancy.
The study revealed that 56 per cent of women who ate more than 2,200 calories a day before conception had a boy, compared with 45 per cent of women who ate less than 1,850 calories.
The researchers found that 59 per cent of women who had cereal every day had a son, compared with 43 per cent of those who had less than one bowl a week.
Women with sons also had higher levels of nutrients in their diets, such as potassium, calcium and vitamins C, E and B12.
Over 40 years there has been a consistent decline in the proportion of boys being born in western countries – a drop of about one per 1,000 births annually.
Dr Fiona Mathews, one of the researchers from Exeter University, said: "This research may help to explain why in developed countries, where many young women choose to have low- calorie diets, the proportion of boys born is falling."
IVF research suggests that high levels of glucose encourage the growth of male embryos, while inhibiting female ones.
In humans, skipping breakfast depresses glucose levels and so may be interpreted by the body as indicating poor conditions and low food availability.
Dr Mathews said having a boy was also linked to higher levels of potassium – which could amount to as little as an extra banana a day before conception.
Higher levels of salt were also consumed by those having boys, though the researcher warned that eating large amounts of salty food could raise blood pressure.
"We could say that if you increase your calorie intake slightly while trying to conceive you may be flipping the odds of you having a boy slightly in your favour," Dr Mathews said.
Bridget Aisbitt, of the British Nutrition Foundation, said there were no specific recommendations for diet prior to conceiving, apart from taking folic acid supplements to prevent spina bifida.
Professor Stuart West, from Edinburgh University, cautioned against using diet to try to influence the sex of a child.
"First, the effect appears to be relatively small, with the sex ratio varying from only 45 per cent sons with low-calorie diets, to 56 per cent sons with high quality diets," he said.
"Second, similar data in animals such as non-human primates shows huge variation between studies, and so it would be key to determine the repeatability of these results.
"Third, diet will have other effects for both the parent and offspring."
The full article contains 550 words and appears in The Scotsman newspaper.
