Melanie Cole (Host): Thanks for tuning in to Back to Health, the podcast that brings you up-to-the-minute information on the latest trends and breakthroughs in health, wellness, and medical care. Today's special episode is part of our Women's Health Wednesday series, which features in-depth conversations with Weill Cornell Medicine's top physicians on issues surrounding women's health throughout the life course. Listen here for the information and insights that will help you make the most informed and best healthcare choices for you.

Host: I'm Melanie Cole. And today, on this Women's Health Wednesday, we're discussing egg freezing with Dr. Isaac k Kligman. He's a Professor of Clinical Obstetrics and Gynecology at Weill Cornell Medicine, a Professor of Clinical Reproductive Medicine at Weill Cornell Medical College Cornell University, and the Ronald O. Perelman and Claudia Cohen Center for Reproductive medicine.

Dr. Kligman, it's a pleasure to have you join us today. Thank you so much. I'd like to start by asking you really the impact of a woman's age on her fertility potential. What happens as we get older?

Dr. Isaac Kligman: So, women have a finite number of eggs that they spend during their reproductive lifetime. The maximum amount of eggs occurs at 20 weeks of intrauterine gestation. When the baby is born, she has about a million available oocytes. But at the beginning of a reproductive cycle when a girl has her first menses, there are about 400,000 eggs available to spend during her reproductive lifetime. And those are spent between the initial period and when the woman reaches menopause. Those eggs not only are spent during the reproductive lifetime, but they also decrease in quality. So after age 35 to 37 years of age, the number of eggs that are available and the quality starts to decline. And that's why it's so important for women to know that they have a reproductive life span of the eggs that are available for them to reproduce.

Host: Wow, Dr. kligman, I didn't know how many eggs we have. That was so informative. Thank you for that. Tell us what is meant by the term ovarian reserve. What does that mean?

Guest: Yes, ovarian reserve is basically the number of eggs that are available at any point in a woman's reproductive lifetime.

Host: Well, that was simple enough. So, we hear about the term fertility preservation. What are some reasons patients may decide to explore fertility preservation options, the conditions under which a woman would consider this option? Because we're talking about egg freezing today. And so, that is part of fertility preservation. Why would somebody look to do that?

Guest: Initially, fertility preservation was developed to help women who were going to undergo what's called gonadotoxic therapies, meaning treatments that were going to affect the ovarian reserve, so women, young women with cancer, for instance, that were undergoing chemotherapy or radiation therapy. And that therapy was generalized to women who were freezing eggs for social reasons. And I think that's a very good alternative for women to preserve their fertility.

So, the first birth from a cryopreserved egg was actually reported in 1986. And since then, the technology has advanced. And in 1999, the technology changed completely because initially the eggs were frozen with a technology that was called slow freeze. So, the eggs were damaged because there were ice crystals that were formed inside the cytoplasm of the egg.

About in 1999, a new technology came about, which was called vitrification. And vitrification basically is a technology where the eggs are very rapidly frozen, so there is no chance for the ice crystals to form in the cytoplasm. And that really revolutionized the entire field because the success rates were significantly higher and the technology could be generalized to women who basically did not have any medical condition, but just wanted to preserve their fertility.

Host: Well then, tell us a little bit more about how egg freezing really works. How are they stored? I mean, we think to ourselves, "Do eggs freeze?" But they obviously do. So, tell us a little bit about the actual process. How are they stored? How long can they sit in the freezer? Tell us some of those details.

Guest: Let me walk you through the entire process of fertility preservation or egg freezing. So essentially, the woman comes to the physician and has a complete history and physical exam. And there is a test called the anti-Müllerian hormone, which is a blood test that gives you an idea of what your ovarian reserve is. There is another test, which is an ultrasound that is called an antral follicle count that counts at a given time how many little follicles are in your ovaries. Once you determine that, then you are given medication to stimulate your ovaries to make this process more efficient. So basically, based on the antral follicle count and the anti-Müllerian hormone levels, you give this patient a protocol which may vary the dose of medication, the dose of stimulation that the patient is going to get. She comes into the office, you do an ultrasound and blood test, and then we previously have instructed the woman how to inject herself gonadotropins, which are the medications that stimulate the ovaries, and then you monitor the cycle. The patient comes to the office every day, every two days, depending on her estrogen levels. So basically, she comes into the office in the morning, we do an ultrasound, we do blood work, and then we get those results. And in the afternoon, we call the patient with her instructions. We tell her what dose of medication she needs to use, and so on and so forth. We monitor the patient until the follicles that contain the eggs reach a certain size.

At that point, we give the patient a trigger shot, which is a different medication. And 35 hours later, we bring the patient to the operating room, give her light sedation. And with an ultrasound probe and a needle, we go to aspirate all those follicles and put the eggs in little test tubes and send them to the lab. The lab gives us an idea of how many mature eggs are available. And at that point, we clean the eggs and freeze them. The eggs are frozen in liquid nitrogen actually. There are the special little tubes that are plunged in liquid nitrogen to make those eggs freeze very rapidly and they can actually be conserved for years and years and years. There are studies that have shown in the literature from embryo freezing which is about the same, that these eggs can be frozen for 10 or 15 or 20 years without having any impact on their chances of turning into a baby, on the chances of being successful.

Host: Wow. What an incredible process that is, Dr. Kligman. So, tell us what you would like women to think about as they go through this. I mean, tell us about lifestyle. Are there certain things you like them to adhere to, whether it's abstaining from alcohol and/or sex, or any of those things while they're going through this procedure?

Guest: It's very interesting. The first thing that I would like to underscore is that women should be aware of age and reproduction, right? Up to age 35, 37, the chances for success are great. And those chances start to decrease after that age. There really are not very important lifestyle changes that need to be made in order to prepare for this process, but it's a good idea to abstain from intercourse during the later phases of stimulation because the ovaries reached three to four times their original size, number one. And number two, you want to prevent a pregnancy when the ovaries are so hyperstimulated and have instead of the one egg that is ovulated every month, you're going to have 5, 10, 15, 20 eggs available. Although you are going to retrieve them, you may not retrieve all of them, and there would be a risk for pregnancy when there is a hyperstimulated ovary.

Host: How long can a woman's eggs remain frozen and still be viable? Can you tell us a little bit about success rates?

Guest: Yes, women's eggs can be frozen for long periods of time, for years actually. There are different ways of looking at success, like what percentage of frozen eggs result in pregnancies and, more importantly, result in live births, in babies? Or how many eggs do women need to freeze in order to be successful later on? So, the way we refer to that is how many eggs does a woman need to be frozen, per baby? So, the younger the woman, meaning between 30 and 35, the woman needs about eight to 10 mature eggs per baby. Between ages 30 and 34, a woman needs like 14 eggs; 35 to 37 years of age, about 15 eggs. And older women, meaning 38 to 40, need about 26 oocytes per baby. That doesn't mean that a woman cannot get two babies from 10 eggs that are mature and so on and so forth. But those are basically the statistics that we have based on previous experiences.

In terms of delivery rates, of live birth rates, those statistics are a little bit more difficult to obtain because the number of women that come back to get their eggs is not very high because women can freeze their eggs, but then when they find a partner or when they decide to pursue their fertility, they can start obviously with their own live eggs and try to achieve a pregnancy through natural conception or even with the different assisted reproductive technologies, and leave those frozen eggs as a last resort because it's like, although they're banked, of course, once you spend them, you have to thaw them, fertilize them, see how many fertilized and, more importantly, see how many progress to what's called the blastocyst stage and are amenable to either be transferred back to the uterus or tested for chromosomal abnormalities.

Host: What if she decides not to use those stored embryos, Dr. Kligman? What happens to unused eggs?

Guest: A woman can keep, as I said before, the eggs frozen for a long time. And if let's assume a 35-year-old woman decides to freeze her eggs and then she decides to get pregnant, and then she gets pregnant and has three babies without resorting to those eggs. The eggs are frozen and then they can be discarded if the woman decides not to use them. It's a little bit different between eggs and embryos, of course. Because with embryos, there is sperm involved, so there is sperm involved either from a partner or from a sperm donor. So although the embryos can be frozen for long periods of time as well, once you decide to discard the embryos, you are discarding the embryos. If you used donor sperm for instance, then it's your consent. But if you used sperm from a partner, then both partners need to consent to discard those embryos.

Host: I'd like you to leave us with one lasting bit of advice. Dr. Kligman, you are obviously so knowledgeable on this subject. What would you like to tell women that are considering fertility preservation technology and specifically freezing her eggs?

Guest: I would advise women to be aware, first of all, that this technology is available, that there are many ways to preserve fertility for social and medical reasons, and that they should be also be aware that age is an important factor on women's reproduction. The optimal age to freeze eggs or to pursue fertility preservation is between 35 and 37 years of age. And women who have no immediate intentions of pursuing parenthood should definitely take advantage of this option because it's widely available.

Melanie Cole (Host): Thank you so much, Dr. Kligman, for joining us today and sharing your incredible expertise. What a nice man you are. Thank you so much. And Weill Cornell Medicine continues to see our patients in person as well as through video visits, and you can be confident of the safety of your appointments at Weill Cornell Medicine. We're so glad you joined us for Women's Health Wednesday. We hope you'll tune in and become part of a community and a fast-growing audience of women looking for knowledge, insight, and real answers to hard questions about our bodies and our health. Please download, subscribe, rate and review Back to Health on Apple Podcasts, Spotify and Google Podcasts.

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