Diet and Gender Determination

I have been hearing and reading for some time now about the belief by some that a mother’s diet can help determine the gender of a fetus.  Generally, this possibility is rejected by scientists and physicians alike.  I too reject this notion–in general.  A British study performed in 2008 argues that “you are what your mother eats.”  In a nutshell, the study argues that women who eat more calorie-dense foods such as cereal are more likely to give birth to a boy.

In a recent string of articles, skeptics and supporters alike have issued responses to this new study.  A recent piece by NPR presented both sides of the issue, but tended to give enough of a shadow of doubt so that the British study remains credible.  However, an article on WebMD is more dismissive of this study.  One researcher interviewed for this article said that trying to influence the sex of an unborn baby has been “of enormous interest forever [and] if something as simple as eating cereal would have made any difference, we probably would have figured it out by now.”  A fertility specialist interviewed for the article added,”What we’ve learned about sex selection in the recent past is that it’s ultimately determined by the father,” although he adds that there may be some factors in the mother’s reproductive tract that may make it more likely for “girl” or “boy” sperm to meet the egg.

It should be pointed out that the impetus for the study was the research done in mammalian biology that indicates that the females of other species of mammals do bear more male offspring when resources are plentiful and/or the mother is high-ranking within the group.  Within the laboratory setting, there has been some evidence that nutrition does directly influence gender-based changes in rats.  However, within humans, there is still no hard evidence that indicates that diet, or anything other than the chance of sperm, influences the determination of gender.

Going back what the fertility specialist commenting in the WebMD article argued, it is probably of most interest and use to study what, if anything, affects the uterine-vaginal-fallopian environment that may prohibit or inhibit the promotion of sperm based their chromosomal contents.  On the surface, it appears unlikely that there is any way that vaginal conditions can differentiate between X-sperm and Y-sperm as there is no real structural or outward difference between X- and Y-sperm.  (Remember the blog entry on sperm.)

So, yet another purported way of predicting or influencing the gender of a baby that has cropped up but is being shot down by scientists.  (Another such proposed way of influencing the gender of the baby is the timing and positioning of sexual intercouse.)  Do you have any theories about this subject?  I would like to hear from you.  Other comments or questions?  My ears are open.

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2 thoughts on “Diet and Gender Determination

  1. Of course, nearly everything I’ve seen about gender determination has either been anecdotal or aimed at selling something. There was an interesting study in the Proceedings of the Royal Society B where the pre-conception diets of mothers were compared to the eventual sex of their children and certain factors such as eating breakfast or eating more nutrients were said to tip the scales slightly (something like 5%). Anyway it wasn’t rigorous, but it was based on the theory that Y containing sperm aren’t as hardy as X containing sperm and therefore any factor that influenced the environment in the vagina would be able to influence which sperm win the race.
    I personally think that a simple survey of fraternal twins could shed some light on the debate. If twins occur in a very even spread: 25% male-male 50% male-female 25% female-female, then I think it would be very unlikely that such factors influence the sex outcome. If there is a significant effect of any external factors, then the female-female and male-male pairs should be (at least slightly) more common than just 25%.

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