How much a mother eats at the time of conception may influence whether she gives birth to a boy or a girl, a new report shows.
The sex of a child may depend on a mother’s diet. (Paul Hilton for The New York Times)The report, from researchers at Oxford and the University of Exeter in England, is said to be the first evidence that a child’s sex is associated with a mother’s diet. Although sex is genetically determined by whether sperm from the father supplies an X or Y chromosome, it appears that a mother’s body can favor the successful development of a male or female embryo.
The study, published in the journal Proceedings of the Royal Society B: Biological Sciences, shows a link between higher energy intake around the time of conception and the birth of sons. The difference is not huge, but it may be enough to help explain the falling birthrate of boys in industrialized countries, including the United States and Britain.
The reason food intake may influence the development of one sex of infant rather than another isn’t fully understood. However, in vitro fertilization studies show that high levels of glucose encourage the growth of male embryos while inhibiting female embryos.
It may be that male embryos are less viable in women who regularly limit food intake, such as skipping breakfast, which is known to depress glucose levels. A low glucose level may be interpreted by the body as indicating poor environmental conditions and low food availability, the researchers said.
The findings are based on a study of 740 first-time pregnant mothers in Britain who didn’t know the sex of their fetus. They provided records of their eating habits before and during the early stages of pregnancy, and researchers analyzed the data based on estimated calorie intake at the time of conception. Among women who ate the most, 56 percent had sons, compared with 45 percent among women who ate the least. As well as consuming more calories, women who had sons were more likely to have eaten a higher quantity and wider range of nutrients, including potassium, calcium and vitamins C, E and B12. There was also a strong correlation between women eating breakfast cereals and producing sons.
The data are limited by the fact that they are based on self-reported food intake, which can be unreliable. However, the consistency of the trend offers an explanation for the small but consistent decline in the proportion of boys born in industrialized countries over the last 40 years, where even though women in general appear to be consuming more, eating habits have changed.
In the United States, for instance, the proportion of adults eating breakfast fell from 86 percent to 75 percent between 1965 and 1991. And although women may be eating more overall, a nutrient-poor diet could be less favorable to a male embryo. Glucose levels may also fluctuate in women who are dieting and trying to lose weight prior to pregnancy. In animals, more sons are produced when a mother ranks high in the group or has plentiful food resources.
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From 1 to 25 of 429 Comments
Did the study say anything about diabetic mothers and frequency of male children? Since diabetics would probably have higher glucose levels in general, would there be some correlation there?
— Mere KnightFROM TPP — No, that issue wasn’t studied.
I don’t know if this will hold up to further study, but it is interesting.
I do think that I had a faster metabolism and was eating breakfast more regularly when I conceived my son at 31 than when I conceived my daughter at age 28. I was exercising and eating more at the time my son was conceived. Thankfully, I have continued that and haven’t had to battle the middle age bulge…yet. (my kids are 10 and 13).
I do think that we eat more calories now, then ever before, though. So if this theory is true, then we should be producing boys in record numbers. Maybe only breakfast calories count?? That would be a weird finding, but you never know.
— rini10Seems to me that the obvious answer lies in genders of children born to diabetic mothers - whose bloodsugars are usually higher than the average nondiabetic woman.
— NicEat food. breakfast through dinner. Make boy.
— KatieYet another poorly conceived study with unimpressive data that falls well within the margin of error and outlier. How the hell do these funding attention ploys keep making the news?
— dumbI wonder if there is an evolutionary function in this: in times of little food and a population in trouble, future-child-bearing girls are more valuable for sustaining the population than a boy. Interesting!
FROM TPP — Yes, the authors cited that bit of evolutionary logic in their paper.
— ColleenIf this hypothesis would be true, overweight women would “produce” disproportionately more boys, which isn’t, apparently, the case.
FROM TPP — Not necessarily because the quality of the food they eat appears to be a factor as well. So a lot of nutrient poor calories may favor girls.
— Konstantin MonastyrskyThe phenomenon described is interesting, but the headline and the way the phenomenon is described are misleading–Mom’s eating habits don’t affect genetic sex, they affect the viability of embryos that are already sexed by Dad. Women have long been erroneously and illogically blamed for not producing sons, and this specious language just provides more ammo for their ignorant accusers and more reason for misguided guilt on the part of son-less mothers.
— beckyHave there been any studies looking at the rates of male vs. female births in women who have diabetes?
Since diabetes is characterized by higher levels of glucose, do mothers with poorly-controlled diabetes have a greater chance of having a son?
— jillSo is this study saying that a fertilized egg with a y chromosome will not even be able to survive in the womb at all, resulting in no pregnancy?
What about what the father eats? Could the amount of nutrients provide better stamina for males and the opposite for females?
The numbers just seem too close for me. There is only an 11% difference between those who ate the most and those who ate the least in bearing male children. You could switch it around and say 55% of those who eat the least have girls and 44% who eat the most have boys.
Was there any statistical data to show that these numbers are statistically and significantly different to reject the null hypothesis?
— EmilyOr perhaps the gender determines the dietary cravings of the mother. If the male fetus requires more glucose to thrive, then it’s logical the mother would need more glucose — craving it — and be less likely to skip breakfast. In biology, making a person hungry is a much easier process than switching the sexes of an animal.
This study seems to be determining cause and effect based off correlation and negotiably supporting evidence.
— JamesIf consummation during conception influenced the sex of the infant, wouldn’t we see patterns? You would think there would be more females in starving countries and more men in affluent countries.
— Steve BilanThis may turn out to be just the tip of the proverbial iceberg once more information is discovered about this miraculous process.
For instance, isn’t it also true that the ph level of the birth canal - whether it be slightly more acidic or slightly more alkaline at the time of conception - slightly favors either X or Y sperm as they swim to fertilize the egg ?
— Joe ParisThis is an informal study based on unreliable data. This study implies that if women are perfect in there eating habits they will more likely produce boys than girls. This is the stupidest thing I’ve ever heard! The only thing that will determine sex of a child is which sperm manages to crack the egg first! Are these researchers trying to say that a better nourished uterus will have an adverse affect on x chromosome bearing sperm? Whether you have a boy or a girl is a coin toss. What women do with there eating habits will have no effect on there children’s sex. If anyones eating habits should be examined it should be the fathers because they are the only ones who can bring that crucial y chromosome to the party!
FROM TPP — Yes, the sperm determines the sex of the embryo but whether or not that embryo is sustained may be decided by the mother’s body.
— BeccaThis is well known from the history of religions…When there is a threat to survival of some species , it takes more females that can be impregnated by few males in order to ensure the highest probability of species survival..
— unity4diversityInteresting article…so maybe my eating all that “crap and vitamins” will help me conceive a boy!!
— AnneYou have to eat more and be sure to eat a breakfast cereal every morning!!
— JasonThis helps me make sense of a theory I heard on NPR a while back: A woman who is living with her sex partner at the time of conception is a little more likely to have a boy than a woman who gets pregnant while not living with the baby’s father.
Girls are more likely to survive infancy than boys are, so it makes sense that a woman who has a baby without the day-in, day-out financial and social support of the baby’s father is more likely to have a girl. I wondered what the physical mechanism for gender selection was, though, and nutrition as the deciding factor makes sense.
I know there are independent single mothers who have the financial and social resources to raise a baby well, no matter whether they have boys or girls, of course. All power to them! I find the idea that environmental factors play a part in whether a woman has a boy or a girl very interesting, though.
Here’s the original NPR story:
http://www.npr.org/templates/story/story.php?storyId=4758495
Here’s an article about why female infants are more likely to survive their first year:
http://www.dailymail.co.uk/pages/live/articles/news/news.html?in_article_id=544069&in_page_id=1770
I don’t vouch for the correctness of the studies mentioned in the above links, but I thought them germane to this discussion.
— HeronVery informative. In Kuala Lumpur, I also noticed that women are producing more girls than boys, and I did wonder about the trend since my first born is a girl too and yes, I had low-calorie breakfast prior pregnancy.
“A nutrient-poor diet could be less favorable to a male fetus” - in other words, the studies seem to conclude that males are basically weaklings compared to their female counterparts. *LOL*
— syAre there more daughters born to women in developing countries?
— DianaSo confusing!
The study was produced in England, and I’m in England.
But I’m American - does this mean my habits are as an American, or as a person in England?
I’d like to stay thin, as would many women, so this means I need to eat healthily, not necessarily a hearty way to eat.
Does this mean healthy eating, to stay fit, and eating heartily, for better nurture, are incompatible?
True, the research’s just been done and published, yet what are women to think?
Can I now eat malteds, fried potatoes (whether called chips or French fries, or by any other name), a feast of fattening cheese, nuts, healthy but calorie-ful, or stick to broccoli, lean protein, fruits, no trans-fats, etc?
For Americans in the U.S. it’s confusing enough. For Americans out of the U.S., what are we to do?
Carole
http://www.Americans-Away-From-Home.com
Carole@Americans-Away-From-Home.com
— CaroleThis is old news. Why do you think they call it a “feed us”?
— YukThe idea of the mother being under stress with scarce food resources producing females because it takes less energy to nourish smaller females could be a factor. I know of a friend who adopted a stray pregnant cat which produced nine females and one male. The health of the lone male also was not so good, despite getting good food from the adopting person. It died after living about 18 months.
— Amy WongNot sure I buy this at all.
— AndreaDoes this mean diabetic moms (who have high blood sugars) have even more sons???!
Looks like a bunch of overblown, headline-grabbing conclusions from a study with serious design flaws. I’m sorry the media only pays attention to reports like this one, instead of well-done studies with negative results.
Andrea
Not really terribly useful, but marginally interesting.
— louisa