BABY BOY: A study of 740 first time mothers in Britain shows that whether moms eat breakfast cereal or not might determine whether their bundle of joy is a boy or a girl.
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Want a son? Pack on the calories. Biologist Fiona Mathews of the University of Exeter in England and her colleagues surveyed 740 first-time mothers on their pre-pregnancy eating habits and found that 56 percent of those on high-calorie diets had sons, compared with 45 percent of those on leaner menus.
But it wasn't only calories that contributed; specific foods also appear to play a role, say researchers. "Prior to pregnancy, breakfast cereal, but no other item, was strongly associated with infant sex," the researchers write in the journal Proceedings of the Royal Society B. "Women producing male infants consumed more breakfast cereal than those with female infants."
The reason is a mystery, but Mathews speculates that glucose may be key. This type of sugar, converted by the human body into energy, is a by-product of the breakdown of carbohydrates such as those in breakfast cereal. Women who do not eat breakfast tend to have low levels of glucose, and other studies have shown that glucose enhances the growth of male fetuses in vitro.
Matthews notes that low glucose levels may indicate to the body that food is scarce, signaling that it would be more prudent to produce a female fetus, which has been found to need less energy to grow. Scientists have also found that cows, deer and horses produce more male offspring when they have bountiful diets.
The researchers took into consideration variables such as the education, size, weight and age of the would-be moms. But there are other variables, such as temperature, hormone levels, and even frequency of sex, that may contribute. "It remains to be seen whether women with greater nutritional intakes, and higher frequency of breakfast cereal consumption, prior to conception are also those with more active sex lives," the researchers write.
But the finding may explain a persistent and puzzling drop in the ratio of male to female births in well-fed industrialized nations, a fact that Mathews ascribes to the decline in the proportion of women eating breakfast. She notes that the number of adolescent girls eating breakfast in the U.S. dropped from 85 to 65 percent between 1965 and 1991.
Such an intriguing finding will need to be replicated in other populations, such as those in developing nations who are chronically underfed, before any definitive conclusions are reached, according to biologist Virpi Lummaa of the University of Sheffield in England, who was not involved in this research but studies human evolution. Researchers in the future might also survey women about their diets before they get pregnant (while their eating patterns are fresh on their minds) rather than after the fact in their quest to prove whether we are, indeed, what our mothers ate.
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10 Comments
Add CommentI thought this was "Scientific" American? You mean if a woman eats a good breakfast, she has a 50/50 chance of having a boy? I'll bet if she stood on her head while eating that breakfast she'd increase her chances of having a boy to about 50/50!!! C'mon, I can understand that scientists get funded for this type of stupid research, but does SciAm really have to report on weak results like these?
Reply | Report Abuse | Link to thisThey stopped being "Scientific" the moment they started pushing Junk Science; letting political agenda dictate scientific results, rather than forming theory from data.
Reply | Report Abuse | Link to thisA gender swing of about 10% is not a weak finding - this sort of thing would have a significant effect on population demographics. It's interesting if it's just a matter of increasing the survivability of the fetus with extra calories, though. As it is, male fetuses are more likely to be conceived (51% to 49%), but tend to reach term less frequently than females, leaving us with a relatively even gender ratio. Let's not forget that with 70% of conceptions resulting in spontaneous abortion, there's a pretty enormous amount of room for gender-selection factors to throw our gender demographics around. With this one playing a role, the more our eating habits will tend to make us fat, the more of a sausage-fest we can expect the place to become. Harsh.
Reply | Report Abuse | Link to thisOh gosh, all those years I blamed myself for having daughters and never suspecting my wife was not having a healthy breakfast! No telling what Henry the VIII would have made of this. No more big feasts in the evening, henceforth they'll be held in the early morning!
Reply | Report Abuse | Link to thisMy goodness. The sex of a fetus under normal circumstance is determined by the DNA provided by the sperm. You know that. Has science changed its perspective on this? If not, then commons sense dictates that swings in the gender of infants at birth would need to accommodate genetic norms. Perhaps the lifestyle of the women in the statistical analysis drives similar attributes (e.g., low glycogen levels) in their male, sperm producing, mate. Who knows? We all do get too wrapped up in mis-interpreted and mis-collected statistics, don't we. What concerns me is that people fret over the gender their offspring and studies like this don't help the situation. Who cares if it's a boy or a girl? They are born human (so far).
Reply | Report Abuse | Link to this> My goodness. The sex of a fetus under normal
Reply | Report Abuse | Link to this> circumstance is determined by the DNA provided by
> the sperm. You know that. Has science changed its
> perspective on this?
No... The survey queried new moms on their [b][i]pre[/i][/b]-pregnancy eating habits. Basically, their diets dictated whether they [i]conceived [/i]a male (XY) or female (XX) baby.
I wonder... did their high blood glucose levels somehow influence which sperm were successful (ie, encourage Y sperm and/or discourage X sperm).... OR, did their high glucose levels increase the odds of a spontaneous miscarriage of a female fetus (or vice versa.... [i]low [/i]glucose = increased odds of [i]male[/i] fetus miscarriage)?
A 56%/45% disparity does seem pretty dubious, especially considering the factors they [b]didn't[/b] take into account.... I imagine hormone levels may be somewhat relevant here. :) Interesting initial data, but they've got a lot more work to do.
I had three sons and never ate breakfast cereal prior to pregnancy, but I was eating a high-calorie diet loaded with sugar.
Reply | Report Abuse | Link to thisI have [b]enjoyed[/b] reading this article and everyones comments.
Reply | Report Abuse | Link to this--
Edited by LDantonio at 04/29/2008 8:48 AM
Why is it so hard for you commenters to understand that in times of famine, an adaptation suited to preserving the species might have an impact on the sex of infants? You NEED more females than males to keep the population going. One man can fertilize 1 million females. Each average female might have 20 offspring at most. Maybe y'all don't like feeling expendable.
Reply | Report Abuse | Link to thisThere are too many variables in this report. They have examined more than 50 types of food for women, and drawn the conclusion that cereals correlate a tiny bit with the number of sons.
Reply | Report Abuse | Link to thisProbability theory says that there will be some significant variable, at least one, which will correlate in this particular survey, but will not correlate when the survey is repeated.