Pre-pregnancy diet linked to sex of baby

Women with a higher calorie intake before conception are more likely to bear boys, according to research published online April 22 in the Proceedings of the Royal Society B.

British researchers analyzed data from food diaries of 740 nulliparous white women, most of whom provided information on their diet in the year before conception. Women in the highest third of energy intake before conception were 1.5 times more likely to have boys compared to women in the lowest third. While analyzing 133 items from a food questionnaire, the investigators found that only breakfast cereal was strongly associated with infant sex. Women eating at least one bowl daily were 1.87 times more likely to bear boys compared to those who ate one bowl or less weekly.

“Over the past 40 years, there have been small, but highly consistent, declines in the proportion of male infants born in industrialized countries. This has caused considerable concern, and is regarded as a health sentinel, possibly of exposure to toxins. However, population-level changes in the diets of young women may explain the pattern. Trends of declining mean energy intake over time among adults and children are reported by most though not all large-scale studies, with the current obesity epidemic being ascribed to declines in physical activity and alterations in the distribution of energy intakes. At the same time, there is good evidence that the prevalence of breakfast skipping is increasing,” the authors write.

Mathews F, Johnson PJ, Neil A. You are what your mother eats: evidence for maternal preconception diet influencing foetal sex in humans. Pro Bio Sci. 2008, April 22. [Epub ahead of print]