Selecting Male or Female Child? Here's How It Works | Dr. Andrew Huberman
00:00:00.000 | [silence]
00:00:02.680 | There are now emerging methods that people are using
00:00:07.100 | in order to separate out the sperm
00:00:10.480 | that will indeed give rise to a male offspring
00:00:14.200 | versus a female offspring.
00:00:15.620 | Now, this of course is done in the context
00:00:17.680 | of in vitro fertilization.
00:00:19.460 | We haven't talked too much about in vitro fertilization,
00:00:21.760 | but in vitro fertilization involves, as the name suggests,
00:00:24.940 | taking an egg and taking a sperm, pairing them in a dish.
00:00:29.200 | This can be done a number of different ways,
00:00:31.820 | but just to briefly describe the IVF procedure,
00:00:34.900 | IVF involves administering supra,
00:00:38.560 | meaning greater than normal, supraphysiological levels
00:00:42.280 | of follicle-stimulating hormone and luteinizing hormone
00:00:45.800 | during the follicular phase of a woman's cycle.
00:00:48.480 | What that causes is the maturation of not just one egg
00:00:52.840 | that would be ovulated, but multiple follicles and eggs,
00:00:57.600 | and then ovulation itself is suppressed
00:01:00.780 | also through the administration of exogenous hormones.
00:01:04.080 | And then under ultrasound guidance,
00:01:06.480 | an OBGYN goes in and collects the mature eggs and follicles,
00:01:10.380 | puts them in a dish,
00:01:11.560 | and then sperm are delivered to that dish,
00:01:13.640 | and those could either be sperm
00:01:14.920 | that were frozen previously, or more typically,
00:01:17.760 | or ideally it would be live sperm collected that day
00:01:21.080 | that are washed through a very straightforward procedure.
00:01:25.040 | And then those sperm either are allowed to compete
00:01:27.540 | for those eggs and fertilize those eggs
00:01:29.680 | and allow them to advance to a very early embryo stage
00:01:33.560 | before those embryos are frozen
00:01:35.080 | and eventually implanted into a woman
00:01:37.320 | in order to have them be carried to full-term, ideally,
00:01:41.200 | or there's a procedure in which specific sperm are selected
00:01:45.120 | because they have the best morphology, motility,
00:01:47.320 | and so forth, and in a process called ICSI,
00:01:50.200 | I-C-S-I, in which the sperm themselves
00:01:53.720 | are literally forced to fertilize that particular egg.
00:01:57.860 | Now, under those conditions,
00:02:01.060 | typically a couple or a woman,
00:02:04.860 | if she's doing this on her own with a sperm donor,
00:02:07.100 | will get multiple fertilized embryos, okay,
00:02:10.500 | that are carried to a multicellular stage
00:02:14.100 | so that it's clear that they could grow into a child
00:02:17.300 | if they were implanted into a viable host,
00:02:20.620 | sometimes the surrogate,
00:02:21.500 | sometimes the woman who wants the child herself.
00:02:24.200 | And under those conditions,
00:02:25.440 | it is possible to look at the genetic makeup,
00:02:27.600 | including the karyotype of those early nascent embryos,
00:02:31.680 | in which case people really can select the sex
00:02:34.680 | of their offspring.
00:02:35.520 | That is, they will have some embryos that are XX,
00:02:39.760 | some embryos that are XY.
00:02:41.440 | It's very likely also that they will have some embryos
00:02:44.760 | that have karyotypes or genotypes which are not ideal
00:02:48.720 | in that they would potentially lead to a miscarriage
00:02:51.160 | or some other genetic defect.
00:02:52.440 | And so typically people do not select
00:02:55.320 | to implant those embryos
00:02:57.960 | if they have the option to implant embryos
00:03:00.840 | that are of either XX or XY karyotype
00:03:04.500 | and the normal chromosomal arrangements
00:03:07.520 | for obvious reasons.
00:03:09.320 | So the whole point here is that sex selection is possible,
00:03:14.080 | but only using in vitro fertilization.
00:03:17.220 | The other thing that is becoming clear to us
00:03:19.560 | in more recent years is that sex selection
00:03:22.560 | is actually possible at the level of the sperm
00:03:24.960 | even prior to fertilization.
00:03:27.100 | This is an emerging dataset,
00:03:29.240 | and this is largely happening in clinics
00:03:31.200 | outside of the United States,
00:03:32.560 | but there are some clinics that have figured out methods
00:03:35.120 | in which they can take a sperm sample
00:03:37.160 | and they can spin that sperm sample in a centrifuge
00:03:40.760 | at a rate that separates out the sperm
00:03:42.920 | into what are called different fractions.
00:03:44.600 | So for those of you done a little bit of biology
00:03:46.240 | with centrifuges, when you spin any kind of substance
00:03:49.180 | that includes multiple things in it of different weights,
00:03:52.440 | when you spin them, the things of different weights
00:03:54.120 | segregate out into different fractions
00:03:56.320 | along the depth of the tube,
00:03:57.440 | and then you can take out one fraction or the next
00:03:59.740 | simply with a little pipette,
00:04:00.720 | you take out the top fraction,
00:04:01.840 | the middle fraction, and so forth.
00:04:03.360 | And what these clinics have figured out
00:04:05.200 | is that if they spin the sperm sample
00:04:07.480 | at the correct spin rate,
00:04:10.100 | that the sperm that will give rise to male offspring
00:04:15.100 | and the sperm that will give rise to female offspring
00:04:17.520 | segregate out into different fractions,
00:04:19.560 | allowing them to take each of those fractions separately
00:04:23.740 | and to apply them to eggs, if it's in vitro fertilization,
00:04:27.780 | and give rise very reliably,
00:04:30.140 | certainly much more than chance,
00:04:31.680 | to either male or female embryos.
00:04:35.380 | They also, of course, can choose to do this
00:04:37.780 | outside the context of in vitro fertilization.
00:04:39.940 | So some people are now opting to have their sperm samples
00:04:43.100 | spun out in this way,
00:04:44.600 | separate out the sperm that give rise
00:04:46.700 | to male or female offspring,
00:04:48.140 | and then to only use the fraction
00:04:51.420 | that they are interested in, right?
00:04:52.900 | So if they want a boy, they'll use one fraction.
00:04:54.460 | If they want a girl, they'll use a different fraction.
00:04:56.820 | And then to use those fractions in the context
00:05:00.180 | of what's called IUI or intrauterine insemination,
00:05:03.540 | which is, as the name suggests,
00:05:05.260 | rather than having the man deliver the ejaculate
00:05:08.640 | with his penis and the sperm with his penis,
00:05:10.300 | they have a device.
00:05:12.300 | The devices are now commercially sold.
00:05:14.380 | Believe it or not, they're sold over the counter
00:05:15.740 | and on the internet.
00:05:16.580 | So people will even do this at home.
00:05:17.900 | And so what they're doing is they'll take the sperm
00:05:20.020 | and they'll do IUI in order to bias the probability
00:05:25.020 | that they're going to get a male or a female offspring.
00:05:27.580 | Again, this is something that's now emerging.
00:05:30.240 | It's not commonplace.
00:05:31.780 | Most of the time, people simply roll the dice, as it were,
00:05:36.180 | by having either intercourse and just hoping for,
00:05:39.860 | or not caring if they get a male or female offspring,
00:05:42.980 | or in the instance of IVF,
00:05:44.380 | selecting male or female offspring.
00:05:45.940 | Sometimes, largely on the basis
00:05:47.540 | of the chromosomal arrangements.
00:05:49.100 | So of course, some people might prefer to have one
00:05:53.580 | or the other biological sex as their offspring.
00:05:55.940 | But of course, the healthy chromosomal arrangements
00:05:59.020 | are going to be paramount for getting a healthy child.
00:06:01.900 | And as I mentioned before,
00:06:04.020 | unhealthy chromosomal arrangements
00:06:05.520 | or abnormal chromosomal arrangements
00:06:07.180 | often lead to miscarriage and/or birth defects.
00:06:10.380 | So selecting for healthy chromosomal arrangements
00:06:13.380 | is always paramount.
00:06:14.660 | But some people are selecting for biological sex.
00:06:16.700 | And indeed, some couples who can conceive naturally
00:06:21.440 | are opting for IUI in order to be able
00:06:24.900 | to select biological sex because of this ability
00:06:27.580 | to spin out the sperm samples to different fractions
00:06:30.880 | and select the male or female sperm.
00:06:33.820 | That is the sperm that would give rise
00:06:35.480 | to a male or female offspring.
00:06:36.760 | So this is a rapidly emerging theme, believe it or not.
00:06:40.780 | Who knew?
00:06:42.100 | And of course, it has nothing to do
00:06:43.500 | with Aristotle's assertions
00:06:44.740 | about what people are thinking about
00:06:46.020 | at the point of ejaculation,
00:06:47.540 | nor does it have anything to do with body position
00:06:50.260 | at the point of ejaculation.
00:06:51.840 | But I do find it rather interesting
00:06:53.340 | that even in this day and age,
00:06:55.220 | people seem to be continually pursuing
00:06:58.680 | new and different ways to understand
00:07:00.500 | why one sperm or another sperm
00:07:02.420 | happens to fertilize the egg.
00:07:05.500 | And when that information is not available,
00:07:08.100 | because frankly, it's not available yet,
00:07:09.580 | we don't know why a sperm containing a Y chromosome
00:07:12.860 | or a sperm containing X chromosome
00:07:14.280 | is more likely to fertilize an egg.
00:07:16.060 | I mean, there's some ideas, for instance,
00:07:17.480 | that older fathers tend to have more daughters
00:07:19.620 | as opposed to sons.
00:07:20.840 | But when you really look at the data, it's pretty mixed.
00:07:22.900 | So if you've heard that before,
00:07:24.660 | has a particular nickname
00:07:26.660 | that I'm not going to describe on the podcast,
00:07:28.460 | you can look it up online.
00:07:29.720 | But if any of you are aware of any other kind of ideas
00:07:33.660 | or lore, no matter how ridiculous or crazy,
00:07:36.360 | please put them in the comment section on YouTube.
00:07:37.980 | I'd be very curious to learn about those.
00:07:40.620 | (upbeat music)
00:07:43.900 | (upbeat music)
00:07:46.480 | (upbeat music)