XX, XY, XHow
January 12, 2020 10:34 PM   Subscribe

I'd like to read about methods for increasing the odds of conceiving a baby of a specific sex. Anecdotal, traditional, superstitious, or, better yet, supported by (even vanishingly small) scientific data- open to all.
posted by nouvelle-personne to Science & Nature (13 answers total)

It seems like IVF (in vitro fertilisation) would be the way to go here. So long as it is legal in your jurisdiction, you can have a pretty much 100% chance of determining the sex of your child by doing it in the lab, and implanting the embryos that meet your sex criteria.
posted by Meatbomb at 11:37 PM on January 12, 2020 [4 favorites]

Eat Veggie to raise chances of conceiving a girl (Same link also mentions time of conception: Y sperm are fast but die quicker, X sperm slower but last longer.
posted by freethefeet at 11:59 PM on January 12, 2020

Shettles method.
posted by cincinnatus c at 2:55 AM on January 13, 2020

(re cincinnatus c's link)

Experts - "Daily is enough, the testes can't supply quality sperm at a very high rate and more frequent intercourse can be detrimental to their viability".

Shettles - "Intercourse should occur from 5 am and continue every 2 hours during the ovulation period"

Every 2 hours from 5am?! The "ovulation period" is usually considered to be a 2 or 3 day window. I'm beginning to suspect this guy's motives... hahaha.

For what its worth I think the "science" best practice way of doing this is Flow Cytometry sorting of the ejaculate prior to insemination. There are commercial providers of this in most countries for animal use, but in less countries for human use. I know Microsort have published research claiming a ~90% success rate when selecting sex in humans.
posted by samworm at 4:14 AM on January 13, 2020 [2 favorites]

There’s a delightful Roald Dahl short story in which a cattle farmer is able to dictate the sex of calves by controlling which way the cow faces during copulation: toward the sun vs away. There’s some general nonsense about gravity and the mass of X vs Y sperm. The story ends with a reveal that the farmer only has male children.
posted by SaltySalticid at 5:18 AM on January 13, 2020

If the male partner eats a lot of bananas, he will produce male children. No science behind it, just something a relative told me once.
posted by lakeroon at 6:44 AM on January 13, 2020 [2 favorites]

There's an enormous amount written about this, what research have you already done? Or are you just looking for a chatfilter of people sharing their favorite folk tales?

As for actual science, the Wikipedia article is a good place to start. The Economist has also written extensively on this topic for years, mostly in the context of selection for boys over girls in China and India. See for example The worldwide war on baby girls and From too few girls to too many men. Selecting gender is very easy if you choose some method that involves artificial conception; you can separate sperm on the basis of X vs Y chromosome.
posted by Nelson at 7:43 AM on January 13, 2020 [1 favorite]

This is a well-researched topic, have you done any reading so far? From what I understand, only methods that actually 'work' (= increase your odds above random) are those involving artificial conception, e.g. sex selection of embryos in IVF or sperm sorting. Those methods are certainly possible but ethically complex and I doubt you'll find medical providers willing to cooperate, but if you really really wanted it, that's the path.
posted by epanalepsis at 8:35 AM on January 13, 2020 [3 favorites]

One of my friends has three children that she claims to have 'selected' the sex of by timing around ovulation.

According to her theory, male sperm reach eggs faster but also die quicker. Female sperm swim slower but live longer.

So when trying for a boy, you have sex on the day you ovulate. For a girl, you have sex the day before you ovulate. Getting the timing right is key, so you need to be temperature tracking daily for several months prior to accurately determine the day you ovulate.

YMMV, but I remember her deciding on the sex this before each pregnancy and she was right every time.
posted by ananci at 8:42 AM on January 13, 2020 [1 favorite]

Came here to mention the Roald Dahl story! The “theory” is that, like the tides, the moon’s gravitational attraction works on sperm. X chromosomes are heavier than Y chromosomes, so the attraction between female sperm and the moon is greater than between male sperm and the moon. So for daughters, the couple should lie with heads pointing towards the moon, and for sons, feet towards the moon. Almost certainly nonsense but it’s a fun hook for the story.
posted by chappell, ambrose at 9:18 AM on January 13, 2020

MicroSort does commercial sperm sorting (with certain conditions) to allow parents to choose gender; it's illegal in the US but can be obtained in Mexico and Switzerland.
posted by crazy with stars at 10:25 AM on January 13, 2020

Lady-Comp, which makes devices that make it easier to chart your cycle previously had a version they sold in Europe that would indicate if you were more likely to conceive a girl or a boy based on where you were in your cycle. Info on their blog here from 2016.
FWIW I started trying to conceive from the earliest possible time through the whole ovulation window for both my pregnancies and both times had girls... so I suppose that's 2/2 anecdata in favour of the earlier = XX; day of = XY.
posted by dotparker at 10:49 AM on January 13, 2020 [1 favorite]

lakeroon that sounds like an unusual application of the Doctrine of Signatures!
posted by unearthed at 1:24 AM on January 14, 2020 [2 favorites]

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