[English] o/t: gender and mum's diet

[stephen at melbpc.org.au]

April 23, 2008,  12:59 pm  http://www.nytimes.com

Boy or Girl? The Answer May Depend on Mom’s Eating Habits

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 eating habits. (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 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. 

==

Cheers people
Stephen Loosley
Member, Victorian
Institute of Teaching




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