If you’re trying to conceive and you wish to influence one way or the other the sex of your baby, new research may give you some tips.

Researchers from Oxford and Exeter universities found that women with the highest calorie intake before conception were more likely to have a boy compared to women on a low calorie diet.

They studied 740 first-time pregnant mothers in Britain (who were split into three groups according to the number of calories consumed per day around the time they conceived) and found 56 percent of those in the group with the highest energy intake at conception had sons, compared with 45 percent in the lowest group. Women with sons also had higher levels of nutrients in their diets, such as potassium, calcium and vitamins C, E and B12, the researchers found. Moreover, women who ate breakfast cereals were also more likely to have boys.

“The effect was linear, that is the more women ate, the more likely she was to have a boy – so the effect might be even larger if women had particularly high intakes. Cereals seem to be one of the key food groups. If a mother has plentiful resources then it can make sense to invest in producing a son because he is likely to produce more grandchildren than would a daughter. However, in leaner times having a daughter is a safer bet,” says Dr. Fiona Mathews of Exeter, lead author of the study, according to Reuters.

Dr. Mathews further says the findings could explain why over the last 40 years there has been a small consistent decline, of about one per 1,000 births annually, in the proportion of boys being born in industrialized countries, including the UK, the U.S. and Canada.

“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,” says Dr. Mathews, adding that there is also a link between higher national incomes and fewer boys.

Moreover, skipping breakfast in the developed countries has become a habit in the recent years. For example, in the U.S. only, the proportion of adults eating breakfast fell from 86 percent to 75 percent between 1965 and 1991.

However, women are not advised to skip breakfast if they are hoping to have a girl. It is already known that people who eat a healthy diet maintain a better body weight and have a better overall nutritional status. Women who skip breakfast just to have a girl could have nutritional consequences in the long run.

“I would urge women to not to start starving themselves in order to try influence the sex of their baby. It has been observed in some animal studies that even small changes in female diet can affect the life long health of the offspring, so it is important that the mother has appropriate nutrition at the time of conception and throughout her pregnancy,” said Dr. Allan Pacey, an expert in fertility at the University of Sheffield, according to BBC News.

The findings are not new, as scientists already know that in many animals more males are born when a mother had plentiful resources or is high ranking. The phenomenon has been most extensively studied in invertebrates, but is also seen in horses, cows and some species of deer.

The findings fail to show if there’s a link between the baby’s gender and a mother smoking and drinking caffeine prior to pregnancy. Also, there was no evidence of a correlation between the body mass index (BMI) of a mother and the sex of her child.

The study, funded by the Sir Jules Thorn Charitable Trust, appeared in the journal Proceedings of the Royal Society B: Biological Sciences.