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Study: Pregnant Smokers Have Girls, Not Boys

Posted by Karen Murphy

pregnant smokerA crude but fairly-effective low-tech method of gender-selection seems to have been stumbled upon by British researchers:  a new study of 9000 pregnancies in Liverpool, England* shows that moms-to-be who smoke are one-third less likely to have male children than moms who don't smoke.  If the dad-to-be smokes, the likelihood drops to almost one-half (this is taking into account other factors such as health and age).

The mother doesn't even have to be a smoker at all, as even second-hand smoke was found to have an effect upon the resulting baby's gender.  This is all pretty significant when you consider that 52%, or slightly more than half (I know you know this but I'm saying it for my own math-deprived brain), of babies born in Western countries are male.  What would the balance be like if no one smoked at all, I wonder? (or if everyone did?)

Researchers still haven't a clue as to the cause of this phenomenon, but they hypothesize that it has something to do with smoking has to do with the effect of nicotine upon the Y-chromosome (which determines gender), and also something having to do with the effects upon the mother (it's known, for instance, that smoking reduces estrogen and thins the cervix, as well as causes other bad stuff, but how this results in gender changes they haven't a clue).

So, if you want a girl, smoke 'em if you've got 'em!  

*damn, I couldn't work the term "Liverpudlian" into this article. 



Comments

 

ChrisH said:

Hm.  Now, I have a totally unprovable hypothesis, based on some factoid I heard a while ago (totally unverifiable, so big hunk of salt...) Male fetuses tend to be more delicate than the female variety, so maybe its not a case of smoking changing the sex of babies, and we know that sex is determined by the male gamete (sperm)... so maybe its just that if a mother's body is stressed by having to deal with the shit in cigarettes, the male fetuses just can't handle it and don't make it past the very early stages of pregnancy.  OR, nicotine might interfere with that first burst of testosterone that makes male babies male.  Hm.  Interesting... wish I was a scientitian...

These studies are always a bit bogus, because while they can demonstrate correlation, they have no way of pinpointing causation.  

April 10, 2007 3:27 PM
 

Ruyi said:

Studies published in New Scientist showed strong evidence that the more unhealthy (and also older) the mother, the more likely they are to have a girl; boy embryos are weaker, one theory, and the other was that a girl is more likely to have and raise a child (thus furthering your genes into one grandchild) while a healthy boy can 'sow oats' and all that stuff (unhealthy mother doesn't have an unhealthy boy to spread his unhealthy genes around). Take or leave the study.

But this could just be another aspect of that. A smoking mother is pretty much going to be of 'low socio-economic status' (as is a lot of Liverpool) and therefore she falls into the unhealthy category in the previous studies.

I always thought it was odd that out of 9 girls in my high school that got pregnant young, lived unhealthy lifestyles and smoked/drank throughout, all had girls. Nine out of nine ain't bad odds, less there's something in our water.

April 10, 2007 6:10 PM

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