Noor: Today we have Dr. Barry Behr. He's an internationally renowned clinical and scientific leader in the research and advances of human reproduction. He's a board certified embryology lab director, and most recently was a professor of obstetrics and gynecology reproductive endocrinology and fertility at Stanford, as well as their IVF Lab Director.

Thank you so much for joining us. Thanks,

Dr. Behr: Noor. Happy to be here.

Noor: Great. Okay, cool. So we really have to start with just the most basic things. Can you just start by giving just a quick overview of when can people get pregnant? Forget about IVF, forget about embryology. Just how does it work the old fashioned way?

Dr. Behr: Well, you asking me the birds and the bees talk? Yes.

Noor: Basically.

Dr. Behr: But, um, people can get pregnant when there's a presence of an egg and the presence of the sperm in the human body. Uh, usually in the reproductive tract somewhere. So that they can unite, uh, form an embryo and implant in the uterus. It can happen as early as a young girl starting her menstruation in her early teens through typically the mid forties at the latest.

Obviously, their their exceptions to, to every situation, but that's the typical age for a woman to be able to get pregnant. For a man really as soon as he reaches puberty, which is also in your teen years, essentially, until he stops having a heartbeat. It's thought that men can really contribute to a pregnancy.

As long as you're alive making heartbeats, you're still probably making sperm in some way.

Noor: Could you talk a little bit about the embryology sides? Basically, I think something that a lot of people don't know is that when people are forming as embryos that I. Actually their gametes are some of the things that form first, right before their brain, before their logs for all these other organs, their gametes form first.

Can you talk a little bit about that, about how, uh, how gametes form in an embryo and how is that different between men and women?

Dr. Behr: Yeah, no, it's, it's, it's really fascinating how, uh, gametes form and where they form relative to where they end up. The gametes make a huge migration during early embryology to ultimately reside in an area.

That's called the genital ridge. And this area of the anatomy is for a certain period of time, undifferentiated meaning that there's not much difference between male and female or X and xy, uh, embryos, but as, uh, embryology proceeds as development proceeds. These germ cells differentiate the organs in which they reside, differentiate, and this is all through genetic programming because the XX and the xy, uh, chromosomes really determine the direction in which these initially undifferentiated gonads will diverge to become male and female genitalia, which house the sperm cells and the the future sperm cells and the future egg cells.

What's very interesting is that eggs go through a developmental pathway that really is on a finite mission. A woman is born a girl embryo. A girl fetus is born with all the eggs she's ever gonna have. In fact, from the minute she's born or from the minute, really they are, uh, deposited in the genital ridge, they go through a huge attrition.

By millions over the time of gestation, and by the time a woman reaches puberty to start menstruation and now actually ovulating these eggs. Whereas a man's XY path of differentiation really results in a self-renewing population of these future sperm cells that essentially allows men or xy, uh, gonads to make sperm perpetually.

There is no finite system of a, a particular number of, uh, primordial germ cells that will be deposited and become eggs for that reason. I mentioned earlier that men essentially in theory, can produce sperm from this renewal, this renewable source of sperm cells to become primordial germ cells. That is to become sperm as long as a man's healthy enough, and I mentioned before, essentially having a heartbeat to be alive.

Noor: Yeah. Yeah, yeah. So, yeah, that's super interesting. So basically a baby girl has more eggs, more viable eggs than actually a 20-year-old or 25-year-old woman because your eggs are just constantly being depleted over time.

Dr. Behr: Correct. It's thought that a woman loses about a thousand eggs a month.

Noor: Wow, that's crazy.

And does that actually, it decreases as you get older, like, so toddlers are losing more eggs than teenagers or,

Dr. Behr: well, I, I'm not an egg decline expert, but what I've learned and studied is that there's a pretty constant decline of about a thousand eggs a month. Even when you are not ovulating anything, you're still losing a thousand eggs a month.

Even when you get 20 eggs from an egg retrieval, you're still losing a thousand. You may be losing 980 eggs that month because you, you were able to retrieve 20, but yeah, yeah, yeah. Constant decline until it's thought that a woman runs out of eggs in her mid forties, which is about the time. That, or the average time that women begin the more serious effects of menopause when they run out of eggs.

Noor: Yeah. So just in terms of the, um, genetics, do you wanna talk a little bit about basically how DNA degrades or changes in eggs over time, and how DNA changes in degrades in, in sperm as well? How does it Sure. What are the similarities? What are the differences? Sure.

Dr. Behr: You know, one of the, one of the advantages that sperm have is that they're always young because they are being manufactured throughout a man's life.

The disadvantage an egg has is that an egg has been laid down prior to birth and it's been sitting in the person's body till it is ovulated or fertilized and fertilized hopefully, and hopefully makes an embryo and implants. The problem with that system is that the genetics of the egg are as old as the individual.

Mm-hmm. Not like sperm. Always a few months young. So, mm-hmm. The, the eggs that ovulate in an older woman have more fragile DNA and potentially more genetic defects than eggs that ovulate in a younger woman, relatively younger woman, and it is thought that the best eggs are ovulated when you're younger.

The worst eggs are remaining as you get older, and therefore the eggs that you ovulate as an older woman have demonstrated higher genetic infidelity. Therefore, the more genetic errors, less ability to correct these errors resulting in embryos that have, or eggs and embryos that have higher chromosomal anomalies or abnormalities than eggs.

Or eggs from embryos or embryos from eggs, excuse me, from younger women who would have a better machinery to correct any abnormalities and a lower baseline aneuploidy rate than an older woman, if that makes sense.

Noor: Got it. So sperm also accumulates mutations linearly over time versus eggs. They have a little bit more of a non-linear trajectory, like at a certain age.

The mid thirties you see a much higher rate of aneuploidy. Do you wanna talk a little bit about that?

Dr. Behr: I think it's just basically related to the age of the machinery in the egg. Mm-hmm. The sperm will have a constant rate of decay because the, the huge variable of age essentially eliminated in sperm production.

The eggs in a woman's body are gonna be exposed to any environmental stress or toxin that she may expose herself to, intentionally or unintentionally. Therefore, the, the accumulation of adverse environmental conditions inside the body could have a dramatic effect on the diplo, the ploidy, the genetic normalcy status of the egg because of its potentially altered environment in a negative way.

You would expect sperms DNA to degrade at a constant rate because it's always being replenished and the risk with sperm and euploidy may be related to the fact that it's reproducing so much that there could be a replication error or something like that, versus eggs that are sitting essentially in Myotic arrest until they're activated.

Noor: Yeah. So can you talk a little bit about sperm freezing and egg freezing? Should everyone do it at 15 now, it sounds really scary. What happens when you freeze eggs and sperm? How do you unfreeze them?

Dr. Behr: The sperm freezing has been around, or semen freezing, has been around for over a hundred years. Um, the idea of.

Preserving sperm is not new. There have been techniques that have evolved that are, to be quite honest, marginally different from the early, uh, attempts using cryo protectants to help maintain the sperms viability through the transition from a liquid semen, seminal plasma to a frozen, a solid, uh, pellet that then gets warmed up.

And sort of reconstituted, so to speak. So it's relatively easy. The techniques are relatively simple to preserve sperm through these various states I just described. Eggs on the other hand, have not been frozen for very long. Successful, really successful egg freezing has really only been around for maybe 10, 15 years.

Um, although we've, the first frozen egg successful frozen egg story was in the mid eighties, we rarely have not been able to do this well until the mid late two thousands. Egg freezing is a much more a technically challenging process. It's much more fragile than sperm freezing. You're dealing with far fewer cells that are harder to, uh, put viably through this transition and fortunately.

The most recent iteration of egg uh, preservation is vitrification, which has proven to be the most viable alternative we have. It is very successful. Fresh is full, better than frozen on anything but vitrification of eggs was a huge breakthrough that's allowed us to give women options to delay childbearing that we never had before, and other options that we didn't have on our sort of menu before, since we're able now to.

Essentially viably preserve eggs routinely.

Noor: So when you freeze and unfreeze eggs, how many do you lose?

Dr. Behr: We are much more efficient with egg freezing than we are with sperm freezing.

Noor: Oh, really? We,

Dr. Behr: yes. When we freeze eggs, we recover 95 plus percent of what we freeze. Wow. The survival rate is very high with sperm freezing.

On the other hand, we lose about 50% of the sperm. But again, when you're dealing with, if you've got 20 million sperm and you lose 50%, you still have 10 million sperm.

Noor: Yeah. You have

Dr. Behr: 10 million sperm and you lose 50%, you still have 5 million sperm. We are not dealing with millions. We are dealing with a handful of eggs.

So we,

Noor: in order

Dr. Behr: to have a viable, clinically useful technology, it has to be that efficient.

Noor: How does that compare to embryos? When you freeze embryos, how many are you able to unfreeze? Well, you know, uh, it's about the same.

Dr. Behr: To make that a little more accurate, I would say eggs are 90% and embryos are 97%. Mm.

So, so why is there a difference? Embryos are multicellular.

Noor: Mm-hmm.

Dr. Behr: You can afford a cell or two to be damaged on an embryo and still have a viable embryo. An egg is, has one cell. Mm-hmm. If that cell is damaged, it has a far greater impact on the viability of that. Cell that egg, then an embryo that has a hundred cells, a blast may have a hundred cells.

So you can afford to lose one or two when you have a hundred. You can't afford to lose one or two when you have one.

Noor: Got it. And then in terms of sperm freezing, how many vials of sperm is it to fertilize? How many embryos?

Dr. Behr: It's really how many sperm are in the vial, to be quite honest. But on a normal man.

Noor: Yeah.

Dr. Behr: Uh, one vial of of semen. Has enough sperm to fertilize as many eggs as he could be challenged with. As I said, there are millions of sperm typically versus a handful of eggs. So one sperm vial, if it was reused or divided up, could be enough for multiple attempts of IVF. Now we don't recommend that because mm-hmm we don't want to have our back against the wall.

But typically on a normal male there, there is sufficient sperm from one ejaculate. Achieve is to achieve multiple IVF cycle.

Noor: Yeah. Can you talk a little bit about sperm sorting? Is there a way to tell which sperm has, uh, an x chromosome and which one's carrying, uh, a y Which one's gonna make it? 'cause obviously sperm determine whether it's gonna be, uh, a boy or a girl.

Is there anything that, uh, you can talk about there?

Dr. Behr: You know, sperm sorting is the. The breakthrough waiting to happen in our field or, or sex selection. Mm-hmm. There is no successful proven method that's clinically available to sort x and y bearing sperm in humans today. There have been approaches using flow cytometry that have worked, there have been approaches using differential density centrifugation that have not worked.

Right now the best way to select the sex of a, of an embryo is essentially sex. The embryo, not the sperm. Clearly, it would be much easier to sort sperm and it's done in domestic animals like cows, for example. Quite effectively, it just doesn't work in human sperm, and unfortunately there, as I mentioned, there is no FDA approved, uh, way to do that today.

Noor: Got it. Okay. Can you take us behind the curtain of the embryology lab? What happens there? How does it work? How are embryos made?

Dr. Behr: The embryology lab is the most amazing room that you can ever go into, in my opinion. It's certainly changed my life and my trajectory, uh, in careers when I witnessed an embryology lab in the mid eighties, so very early in the uh, uh, US world of IVF.

So labs were not as sophisticated as they are now, but it's really an area, a room where life is created. It's a, a room that has limited access due to its high value cargo, due to its exquisite conditions that need to be maintained to allow this process to continue effectively and efficiently. And due to the, the equipment and conditions settings and things that are and are at high risk of changing, that could affect things in a negative way.

So it's essentially a room that has microscopes, incubators. A lot of other medical equipment like centrifuges and water baths and pH meters and uh, liquid nitrogen tanks, gas fittings, water bottles, gas bubblers. Filters, syringes, Petri dishes in a very controlled air environment. So the temperature and the particle count is very strictly controlled.

We wear special clothes, we wear scrubs, we wear very much like you wear in an operating room.

Noor: Yeah. So could you give us sort of the play by play from when the eggs get retrieved, what happens? How many days does it take? Who is, how many people are involved? How many Petri dishes? Just kind of, uh, walk us through the story.

Sure.

Dr. Behr: After about 12 to 14 days of shots and ultrasounds and blood tests, a woman is ultimately ready to have her eggs retrieved, and this is determined by a variety of of interrogations. To pick the apple at the perfect, ripe, ripe stage, IE go into the follicles and retrieve the eggs at the perfectly ripe time.

An average of 10 to 15 eggs is re, are retrieved from a woman of which 80% are mature. IE are ripe. So not every egg that is is harvested from a woman is, is usable, but the majority are, once the eggs are retrieved, they, the eggs are, are delivered to the laboratory in a test tube that is fooled with follicular fluid.

So the egg floats in a follicle in the woman's ovary and the reproductive endocrinologist doesn't suck the egg out. They empty the follicle. It's like popping a blister and empty the fluid, and hopefully the egg comes along with it. The embryologist then looks through that fluid to find the egg and collects all the egg from the tubes that come.

This is where test tube baby comes from, by the way. It's the only place an egg sees a test tube is when it's retrieved.

Noor: So how are those eggs collected?

Dr. Behr: So the, the fluid is poured out into it's aliquot, into several Petri dishes. The Petri dishes are scanned physically under the microscope by a trained embryologist to identify them, and once the eggs are identified in the follicular fluid, a pipette, a pasture pipette.

Which is like a, a very finely controlled eyedropper, if you will, is used to pick up the egg in the fluid and put it in, collect it in culture medium that is being kept at body temperature, at the right, acid-based balance at the right humidity during the egg egg retrieval procedure.

Noor: Is there a difference between embryologists in terms of if you get them out faster, do more eggs survive?

If they get them out slower, do fewer survive well or is it They're pretty strong and they can handle anything.

Dr. Behr: The, a good embryology lab has conditions to. Help maintain body temperature throughout the retrieval process and the identification process. You definitely have some wiggle room rushing and trying to be too quick is not good.

Leaving your eggs out while you go have lunch. Obviously it's unacceptable, but do we want wiggle room to take your time to identify the eggs? We have eat surfaces, we have guest bubblers. We have things that maintain the conditions while we find the eggs. Of course. Being efficient, being able to be fast and effective is better than being slow.

But qualified, trained, embryologists, do it in a, in an appropriate amount of time, that should not negatively affect the viability of the eggs.

Noor: Great. Okay, cool. So we, we have our eggs, culture media. Oh. We

Dr. Behr: have the, uh, all eggs on one basket now. And while the eggs are being collected and evaluated, a sperm sample essentially is being produced or is being received by the lab so that the sperm processing for, uh, the specific type of insemination can commence.

We do not typically inseminate or do, uh, intra cytoplasmic sperm injection, which I'll explain in a minute, sooner than two hours after collection. We only inseminate eggs or inject them between two to six hours after collection, and this relates to their most viable fer fertile window. Mm-hmm. There are two ways that an egg can fertilize.

One is through natural insemination where sperm is washed, it's processed, and it is essentially dumped on the eggs and let them swim together for an overnight date. Uh, and we check them in the morning to see who got in and who didn't. Versus Ixi Intracytoplasmic sperm injection, which is a procedure where we take a single sperm and inject one sperm into each egg.

And this is really designed for people who have risks of poor or failed fertilization, although it's being far more widely used now across, I would say most patients have this done, even though by. Diagnosis. They don't technically need it.

Noor: Got it. And then what would people expect in terms of the funnel from eggs that survive long enough for this window to be fertilized, whether by ixy or conventional?

What's the drop off that they should expect?

Dr. Behr: I think it's reasonable to expect that 80% of eggs are mature. So let's say you get 10 eggs, only eight will be candidates for being fertilized because of their, mm-hmm. Their maturation status. Of the eight, you would expect about 75% to fertilize. Okay? So I would expect out of 10 eggs, I would have six fertilized out of those fertilized eggs, which by the way, the day after the eggs are collected, you know the fertilization, it's about 16 hours or 18 hours after you do the fertilization event, can you determine the fertilization status?

Four to five days after the the eggs are fertilized. They should form a blasto cyst, which is the stage at which you would freeze them, transfer them, biopsy them.

Noor: Mm-hmm.

Dr. Behr: About out of your 10 eggs, I would expect three blast assists on average. So that is the drop off. 10 eggs, eight mature, six fertilized, three blasts.

That's the textbook scenario.

Noor: Got it. And then what is a blasty? How is that different than an embryo? Yeah,

Dr. Behr: good question. A blast assist really is the first differentiated embryo that is visible. An embryo prior to the blaster assist is really like a bunch of grapes. Mm-hmm. It's ought to be eight to 16 identically, or 20 or 30 identically genetically identical cells.

They're just sort of budding. They divide one to two, two to four, four to eight, et cetera, et cetera. Once the embryo starts forming a blasts, you now have different types of cells. So the cells, not only do they look different, they actually have different roles. You have cells now that are destined to become the placenta, and you have cells now that are destined to become the fetus, and that's what you have in a blasts.

You have cells that are fetal destined, and cells that surround it, that are destined to become the placenta and involved in implantation in the uterus.

Noor: Got it. So, yeah, can you talk to us about how the, how the biopsy works? Does it harm the embryo? How many cells do you need? Does it come from the fetal DNA or does it come from that placental, DNA?

Dr. Behr: Sure, sure. Embryo biopsy or blasts. Biopsy, or more accurately stated trifecta, derm biopsy, which is the placental layer of the blast assist, is becoming very commonplace now, and I really believe that if a biopsy's done well. That it has a minimal impact on the, on the blaster assist, the, the biopsy really involves the removal of three to five cells on average from the trifecta derm, which makes up probably 60 to 70% of the cellularity of the total blaster assist.

So let's say a narcissist has a hundred cells, 70 cells will be in the trifecta, and 30 cells will be in the inner cell mass, which becomes the fetus. So if we are taking. Two or three to five cells from the embryo. We are really taking a very small percentage, three to 5% of the embryo, let's say, for analysis.

And we are not taking the part from the blasters that that becomes the fetus. We're taking the part that becomes the placenta. And there are plenty redundant cells there that are able to be lost without affecting the viability. But remember what goes along with bio biopsy most times is freezing. Mm-hmm.

So it's not just the, the risks or the. Impact of the biopsy itself. It's the upcoming freezing and hawing or the vitrification and warming of that blast assist that has to be considered part and parcel of the biopsy itself.

Noor: So how exactly does the biopsy happen? Is it with a pipette? Is it the laser? How does it happen?

Dr. Behr: The biopsy happens by placing a blast assist on in a dish, on a microscope that has pipettes on it. That allows us to. Position and anchor the Blast Assist so that we can use a laser to actually cut some of the cells off the Blast Assist so we can pull them off into a pipette. And get them into a tube for analysis ultimately.

Noor: Got it. Okay. And could you talk a little bit about, now people are doing egg freezing for multiple reasons. Can you talk a little bit about, is there anything known about the actual quality of the eggs and embryos that survive this whole process compared to. The eggs and embryos that maybe would have met in a traditional way at the same age?

Dr. Behr: Yeah. No, I really believe that vitrification, the breakthrough of egg vitrification really has allowed us to, for the most part, freeze time for, for the eggs. There's no question that there's the potential for some damage or some loss to occur that would essentially not be a level playing field, fresh versus frozen.

The question always is how many eggs to freeze? Since there is no technology yet to really establish whether an egg defacto can fertilize and make a blast assist or not, we tend to error on getting more eggs than running out of eggs. But you could have, you could have a hundred eggs that are not good.

So we still are at the mercy of, without fertilizing an egg and challenging it. To go to a blast assist. We're at the mercy of the risk of low or poor fertilization that would result in low or poor blast assist formation. But with fresh eggs, there's probably slightly less of a risk of a poorer outcome, but certainly vitrification using.

Using vitrification with fresh cytes has really allowed us to extend the reproductive age of women, has allowed us to allow women who may undergo some gran toxic treatments. To still have children, uh, without after they survive these, these trying treatments and toxic treatment.

Noor: Chemotherapy, yeah.

Dr. Behr: Therapy. It can allow XY individuals to potentially, uh, have babies. So there are many positive ramifications of the breakthrough of egg vitrification that go beyond just giving a woman reproductive freedom, which I think it has.

Noor: Yeah, so those five to six cells that are sampled, so those are sent off for genetic analysis.

Can you talk a little bit about what excites you about whole genome sequencing for embryos? Yeah.

Dr. Behr: Well, I mean this is the area of most excitement for me, at least in the field, is the genetics and what can be done with those three to five cells. The technology is rapidly evolving. Especially with Orchid, being able to do whole genome sequencing now on a representative number of cells from the embryo is remarkable.

I truly believe it's gonna be, it's gonna be life changing with the type of information that we are gonna be able to get from a single biopsy. I think, uh, arguably in the future it could be irresponsible to to, to conceive without knowing what's in your hand before you play it, so to speak. What we know now and what we don't know really is what excites me because of course, it's a slippery slope, and we have to do this with the utmost caution, with, with weigh in from bioethicists and just make sure we're going down the path of most caution and most potential benefit.

Uh, too much of a good thing is not a good thing, but I'm most excited about being able to do this responsibly. And again, the things we don't know about excite me too. Because as I've seen, as I've gotten better perspective and better vantage points, as I've learned more about the potential of these technologies, it's really, it's excited me even more about what the future holds for procreation through our technologies.

Noor: Can you talk a little bit about how genetic testing has changed since the beginning, uh, of IVF and what the differences are and, and what types of information is available? Right now?

Dr. Behr: It's genetic testing has evolved unbelievably over the last several decades, and I think we're, we're in the middle of a genetic revolution, if you will, so I think they could, they're changing as we speak, but we've gone from whole chromosome level detection down to.

Single gene level detection using easier approaches for the embryologist, which is unbelievable because I can tell you, when we did our first chromosome, whole chromosome counting using fish, we had to do things as embryologists that we were never trained to do properly to fix nuclei on cells and worry about overlapping nuclei and making calls that were very difficult to make, putting geneticists in tough positions.

We've gone from that where there have been arguably several papers that have argued its utility to getting to absolute definitive results that are irrefutable, clearly gone from shades of gray to pretty much black and white with resolution that we never had before. We've gone to versions of, of encyclopedias down to, not book chapters, but down to misspelled words in the volumes of exci encyclopedias.

Noor: And it's basically requires basically the acceleration of technologies from so many different fields, from chemistry, from bioinformatics, for sequencing to get cheap enough for the databases to get large enough. So it's really building on the backs of many different fields and many different giants. No,

Dr. Behr: it's absolutely.

I think one of the cornerstones of this breakthrough is the, um, synergy between multiple professions and technologies to get to the place where you can actually do it in a cost effective way and have a meaningful outcome.

Noor: Yeah, so IVF is becoming, I would say, much more normalized than it was 20 years ago, 10 years ago, where there was a lot more stigma around it, taboo around it, it didn't work as well.

So for couples that are considering doing IVF, not for infertility, but just because they want to have children later or they wanna get results for their genetic screening, how do they weigh that decision between. Traditional conception versus IVF in terms of the quality of the egg, in terms of the quality of the verb.

Does it make sense to freeze now and use later? Or how, how, how do they make that decision? How can they start thinking about that in an intelligent way?

Dr. Behr: It's having, starting a family is no, is no simple decision. Having options in your family building is one of the, the luxuries that most people can't afford, but giving.

Given what IVF can offer nowadays, I think it's something that we're not gonna be able to afford not to do in the future, given the information that we can get before we commit to who's gonna be born. There's no question in my mind that IVF is gonna be the most common way to conceive. In the future. Now, whether that's in a decade or two or three or five, I, I don't know, but there's no question in my mind, given the kind of information that we can derive from an embryo about the health of an of the individual to be born, it makes no sense for me to roll the dice and just hope I have a normal healthy kit.

Clearly, this one size dot does not fit, fit all across our planet. But I'm speaking now in United States, in western countries, in cosmopolitan cities where, uh, human beings have this luxury. It's gonna go that way. I have no doubt. I.

Noor: Yeah, you talked a little bit about, hey, you know, 900 eggs are, are lost every month.

Is there anything that's known around the, just the biology or the mechanics of which ones are lost versus which ones are able to be retrieved just from the egg retrieval, and then similarly, which ones actually survive? Is there any way to compare, Hey, this is the egg that would've been fertilized naturally and this is this, the.

The quality of the egg or the embryo that was created in the lab?

Dr. Behr: No, unfortunately not. There's a highly complex selection process that goes on in the ovary during each menstrual cycle mm-hmm. Of about a thousand eggs that start this journey to recruitment and ovulation. Only one makes it. Mm-hmm. And it is not extremely well understood.

What makes one egg, the egg and whether that egg is that much better than the egg next to it or two eggs down. But it's involves a very complex feedback system with growth factors and differentiating factors that ultimately culminate in a single egg being ovulated. So we don't know when we get 10 eggs, which was that egg that was gonna be the chosen one.

We don't feel, there isn't really evidence to show that out of those 10 mature eggs or the eight mature eggs out of 10 that we got, that there's any sort of hierarchy in egg quality out of the mature ones. And to be quite honest, a lot of my research and and current interests revolve around try to develop, uh, an interrogation system for egg viability because it would be quite helpful to help make decisions in, in family building.

Noor: Got it. So basically just in terms of the science, there's not, it's not really well understood what the mechanism is for, this is the egg that was ripened and it's, is it similarly not well understood for which sperm is the one that is able to fertilize the egg, or is there more known about the winning sperm?

No, there's

Dr. Behr: nothing much known about the winning sperm or the winning egg, to be quite honest, other than. They need to have certain prerequisites. IEB Chromosomally normal have certain physical constraints that allow the them to meet IE enough sperm with enough motility to get into the egg. But no, there is no way to differentiate or identify those.

Noor: So what do you think the biggest misconception is for patients who are going through IVF today?

Dr. Behr: I think the biggest misconception is that patients think that IVF is a one shot deal. And IVF should be viewed as a course of treatment. We're lucky if it works the first time. We try our hardest to get it to work the first time, but you need to set your expectations right, that it typically takes more than one shot to, to hit the bullseye and you need to expect to do the more than once.

Noor: Got it. Thank you so much. This was such a exciting discussion about all things from eggs to sperm to embryos, and it was a really a pleasure to host you. Thank you so much. Thank you

Dr. Behr: very much. Take care. Bye bye.

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