Mom's diet seen as factor in whether baby is boy or girl

[Psihala]

Women can influence the gender of their child with what they eat before they conceive, according to new research that lends scientific support to age-old superstitions about pregnancy.

http://www.cnn.com/2008/HEALTH/04/23...iet/index.html

[zephyra]

If only we could force twins, like in The Sims.

[phaed2]

"The discovery shows higher calorie intake prior to conception can significantly increase the chances of having a son while women on restricted diets are more likely to produce daughters."

The meaning of the word "significance" is alway a bit confused among laymen. A result can be statistically significant, meaning that it isn't random, however the magnitude of the effect can be small. The problem is that when the media report something has a "significant increase/decrease", people think they are talking about the magnitude of the effect.

If you give an novel blood pressure medication to a large enough group of people (say, N=20,000), you can detect a 1 point drop in BP as statistically significant, but would anybody bother taking a BP medication that only drops their BP by 1 point? You have to look at the magnitude.

They say you can "significantly increase the chances of having a song," but the truth is revealed later in the article: "The researchers said that a higher calorie intake prior to conception can increase the chances of having a son from ten to 11 boys in every 20 births."

In other words, you can alter the chances of having one or the other gender by up to 10% (and who's willing to bet that "11 in 20 births" was rounded up? The study is here but you have to purchase it.)

In other words, don't hold your breath on this method.

[Grand Illusion]

Originally Posted by phaed2

The meaning of the word "significance" is alway a bit confused among laymen. A result can be statistically significant, meaning that it isn't random, however the magnitude of the effect can be small. The problem is that when the media report something has a "significant increase/decrease", people think they are talking about the magnitude of the effect.

I've always said that statistics is a key deficiency in many people's knowledge sets.

[BlushingBride]

Originally Posted by zephyra

If only we could force twins, like in The Sims.

You mean you can't?? Man, no wonder eating all that pre-whoohoo spaghetti didn't work. And here I thought I just didn't have enough meatballs.

[Mycroft]

I would have thought that the main difference would have been the survivability of the embryo (especially early on, mainly pre-implantation.

I also believe that X and Y carrying sperm cells are physically different (if i remember correctly 'male' sperm are faster whereas 'female' sperm have greater endurance and survivability in hostile conditions), and female internal environment can be affected by diet (or deliberate manipulation via douches), favouring one variety of sperm.

[Jahungo]

The researchers said that a higher calorie intake prior to conception can increase the chances of having a son from ten to 11 boys in every 20 births, according to the study published in the Proceeding of the Royal Society B.

They said it could explain why male births in richer countries are experiencing a slight reduction.

This statement is interesting, and I'm not sure I really get what it means. If higher calorie diets increase the likelihood of boys being born, then one would expect more boys to be born in rich countries, where people have higher calorie intakes. So are they saying that people in rich countries are eating lower calorie diets now than in the past, causing a reduction?

[Jahungo]

Originally Posted by Mycroft

I would have thought that the main difference would have been the survivability of the embryo (especially early on, mainly pre-implantation.

I also believe that X and Y carrying sperm cells are physically different (if i remember correctly 'male' sperm are faster whereas 'female' sperm have greater endurance and survivability in hostile conditions), and female internal environment can be affected by diet (or deliberate manipulation via douches), favouring one variety of sperm.

I think the difference would be due almost exclusively due to sperm competition and differences between X and Y sperm. After all, almost all early embryonic development is driven by maternal mRNA rather than the genes of the embryo itself, so whether the embryo is XX or XY should have little impact on survivability (unless there's something I'm missing).

However, X sperm are significantly heavier than Y sperm because of the extra DNA they carry. (The X chromosome is very large, while the Y chromosome is tiny). Therefore, in certain environments Y sperm will be favored, while X will be favored in other environments. I believe it has a lot to do with the consistency of mucus in the female.

[London Wolf]

Originally Posted by Jahungo

This statement is interesting, and I'm not sure I really get what it means. If higher calorie diets increase the likelihood of boys being born, then one would expect more boys to be born in rich countries, where people have higher calorie intakes. So are they saying that people in rich countries are eating lower calorie diets now than in the past, causing a reduction?

I don't know about richer countries but I read in The Selfish Gene that more girls than boys were born in the Depression and during wartime. Richard Dawkins seemed to think of it as a combination of diet and other factors 'telling' the woman that times were harder, and girls are more likely to survive to adulthood in times of stress, so the good genetic strategy is to have girls.

[imjustasteph]

Originally Posted by zephyra

If only we could force twins, like in The Sims.

Supposedly there's some herbal supplement you can take at a certain point to make the body either more likely to release two eggs at once, or to make the egg more likely to split. I don't remember what it is, though, or at exactly what point you take it (I think it's everyday for two weeks). And of course I don't know if it works. Even if what I read is accurate, it only increases the chances, there are certainly no claims it becomes a sure thing.

But what I was trying to say, before I distracted myself, is that there are some notions (superstitions?) that one can cause twins.

[mindiloohoo]

Apparently diet can contribute to whether you have twins, too!
http://www.africanloft.com/eat-more-...irth-to-twins/

There's a tribe in Africa that has a lot of twins. Scientists think it's linked to a certain type of yam.

I've always wanted twins, so I keep threatening to eat nothing but (specific, hard-to-get) yams when we're TTC in a few years.

[imjustasteph]

Originally Posted by mindiloohoo

Apparently diet can contribute to whether you have twins, too!
http://www.africanloft.com/eat-more-...irth-to-twins/

There's a tribe in Africa that has a lot of twins. Scientists think it's linked to a certain type of yam.

I've always wanted twins, so I keep threatening to eat nothing but (specific, hard-to-get) yams when we're TTC in a few years.

I bet that's what it was I read about- but it was in capsules, I think. I think I remember reading about that tribe.

But this was two years ago when I was pretending to myself that I'd wait until my girl was 5, have twins (through whatever hocus pocus necessary, be it spells or herbs) and then quit.

[RivkahChaya]

It takes more energy to make a boy. At about six weeks gestation, boys takes a Y-chromosome guided developmental detour, and when it's over, have to develop faster to catch up by delivery. A newborn girl is developmentally more like a three-week-old boy than a newborn boy, as a result, and this is why girls are more likely to survive difficult deliveries, peri-natal illness, and prematurity, as well as be alive one year after birth. As the stats claimed when I read them in college, about 105 boys are conceived for every hundred girls (based on stats of girl vs. boy pregnancies detected around 20 weeks gestation), but they are born in about equal numbers, and after one year, about 105 girls have survived for every 100 boys.

So I wouldn't be surprised if having a better caloric reserve increases the viability of conceived males, rather than actually causing more males to be conceived. Since sex can't be determined until the end of the first trimester, there's really no way to know just how many male vs. female sperm actually meet egg. At least not yet.

And umm, if women on restricted diets, rather than just slightly lower calorie diets (ie, women who are smaller or not very active, and have lower caloric requirements), are having more girls, that could be a result of girls being hardier, and more able to survive early gestation in a deprived environment.

The article doesn't seem to discuss health of resultant babies, ie, whther the girls of calorie-restricted mothers have higher levels of birth defects, low birth weight, prematurity, and so forth.

The fact that the influence of diet is pretty small probably accounts for the fact that you don't see an over-abundance of boys in poverty-stricken countries. Also the fact that we are talking calorie-restricted diets from a US/European perspective, no doubt, which probably means something like 1600-1800 calories/day, (vs. 2200-2500 for the non-restricted), and not the 900 calories a day that people in Rwanda may be averaging.

[Artemis]

Originally Posted by zephyra

If only we could force twins, like in The Sims.

Wow, you can do that on Sims? Not that I've played the Sims in years, but how?