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*1 Many people say “vagina” when they mean “vulva” and mistakenly use the terms interchangeably. The vagina is the muscular canal-like tube inside the body that connects the uterus to the vulva. “Vulva” refers to the outer genitals that you can see (including the pubic mound, the labia, the clitoris, the vaginal opening, and the opening to the urethra).
*2 Labia are the inner and outer fleshy folds of skin of the vulva, found at the opening of the vagina.
*3 A major (for many, the main) area of sexual sensation, the clitoris is a complex network of erectile tissues and nerves located above the vaginal opening. The clitoral hood, about the size of a pea, is the only part that’s visible, but the whole clitoris is much bigger. The majority of the clitoris is internal, is about 3.5 to 4.5 inches long, and stretches down either side of the vagina in a wishbone shape.
*4 The Latin word given to the female genitalia, pudendum, literally translates as “part for which you should be ashamed.”
*5 Which sounds dramatic, but it’s true: Some STIs, such as HIV and syphilis, can be fatal if left untreated.
*6 Ovaries, by the way, are the female gonads. Gonads, or sex glands, are the male and female primary reproductive organs. (The male gonads are the testes.)
*7 When I asked a fertility doctor about why this range was so wide, she explained that we don’t really know, but that this is in part why egg count fluctuates based on the individual. If a woman has a lower egg supply than expected for her age, she was perhaps born with fewer eggs or went through them more quickly.
*8 Some women can release two egg cells per cycle, which can result in the conception of fraternal twins. Identical twins—genetically the same, unlike fraternal twins—are made when the fertilized egg cell divides in two.
*9 While it’s a biological reality that fertility in human females declines over time, most female mammals, including chimpanzees, maintain the ability to get pregnant for most of their lives.
*10 There are a few different terms used to describe freezing eggs for non-medical reasons: “elective egg freezing” (has insurance implications, best to avoid), “social egg freezing” (makes it sound more fun than it is), and “planned egg freezing” (better than the other two terms, the idea being you’re preserving your fertility now because you plan to have children later). The qualifier isn’t really needed, though, and most people refer to it simply as “egg freezing.”
3 Egg Freezing’s Rise
Mistress of Her Own Body
Brooklyn, 1916. On a bright mid-October day in Brownsville, then a poor and densely populated area of Brooklyn, the country’s first birth control clinic opened its doors at 46 Amboy Street. Margaret Sanger wasn’t sure what to expect and was taken aback when well over a hundred visitors came that opening day.[*1] The pamphlets advertising the clinic were printed in English, Yiddish, and Italian. They read: “Mothers! Can you afford to have a large family? Do you want any more children? If not, why do you have them? Do not kill, do not take life, but prevent. Safe, Harmless Information can be obtained of trained Nurses at 46 Amboy Street.” For the next several days, Sanger worked with her sister Ethel, a nurse, and their friend, an interpreter, distributing information about birth control to more than 450 visitors in all.
Ten days after it opened, local authorities shut the clinic down. Sanger was arrested, charged with disseminating information relating to contraception, and later served thirty days in the Queens County Penitentiary. But her mark had been made, a century-long process begun. The clinic pushed the topic of birth control into public debate, marking a seminal moment for the women’s rights movement and igniting a series of changes in how people regarded contraceptives. Sanger would go on to establish what became the precursor to today’s Planned Parenthood Federation of America.
“Woman can never call herself free until she is mistress of her own body,” Sanger wrote in an essay titled “Morality and Birth Control.” She was one of her generation’s leading female revolutionaries and activists, pushing for structural change and fighting back against repressive policies on contraception and abortion. In a deft show of marketing prowess, Sanger used the term “birth control” instead of “contraception,” to make it sound less draconian. Separating sex from reproduction was a key first step, but there was more to the movement than that. The new term didn’t invoke sexual connotations, declarations of independence, or threats. “Birth” was fine; without birth there could be no life, everyone accepted that. For Sanger, Jonathan Eig writes in his book The Birth of the Pill, “the key word was ‘control.’ If women truly got to control when and how often they gave birth, if they got to control their own bodies, they would hold a kind of power never before imagined.”
For much of history, women had very little say when it came to their bodies—especially in the bedroom. Married women were typically barred from employment, spending countless hours raising children, confined inside houses under the direction of their husbands. Saddled with childbirth and childcare, they had little power or self-determination. Sanger made it her life’s work to see to it that this changed, that women gained autonomy at least over their reproductive lives. But with no reliable methods of birth control available, many women found it difficult to free themselves from being trapped by multiple pregnancies.
They did try. One of the worst examples of the lengths women went to avoid getting pregnant was using Lysol, the harsh cleanser for mopping dirty floors and scrubbing toilets. Women would use it as a douche, and Lysol’s advertisements actually encouraged women to employ the disinfectant as birth control. At one point during the Great Depression, it was the bestselling method of contraception. (No, Lysol is not effective at preventing pregnancy; yes, it is dangerous to use Lysol in this way.) Women experimented with a few other means of contraception, but the big shift didn’t come until the late 1950s, when oral contraceptive pills were first introduced.[*2]
The U.S. Food and Drug Administration (FDA) approved Enovid, the first birth control pill, in 1960.[*3] Since then, hormonal birth control has allowed millions of women to exert control over their fecundity. Still, it was a rocky start. Even though the Pill was available, doctors in many states could not legally prescribe it. The federal government and many states had anti-birth-control laws in place. Before laws were on the books allowing for birth control services, whether or not a woman could legally take birth control was largely determined by her relationship status. In 1965, the Supreme Court deemed the Pill legal for married women. It wasn’t until 1972 that it was ruled legal for all women, regardless of their marital status. Meanwhile, companies had begun to develop and sell various types of IUDs, or intrauterine devices, inserted into the uterus; today’s IUDs are T-shaped devices about the length of a large paper clip, made from flexible plastic and sometimes copper. By the early 1970s, nearly 10 percent of women in the United States using contraception relied on the IUD.
Then came the Dalkon Shield.
During the first few years of the IUDs’ heyday, over two million American women were fitted with this particular IUD—advertised as a safer alternative to the Pill—and it quickly became the most popular one on the market. Then women started getting sick. The Dalkon Shield, it turned out, was defective in detrimental, life-changing ways. Created by a doctor and an engineer, this new IUD—called a shield because it resembled a police officer’s badge—was nearly circular, with five small plastic fins along two opposite sides that secured the device in place in the endometrium (the tissue that lines the uterus). The device’s larger surface area necessitated a more durable tail string compared to the tail strings of other IUDs. The doctor and the engineer identified a string they thought would work well called Supramid, a cable-type suture material made of hundreds of small fibers wrapped by a single sheath. It was the device’s multifilament string that caused bacteria to get trapped in the string and therefore the uterus. Thousands of patients suffered infections, miscarriages, and a host of other significant problems. More than three hundred thousand claims were filed against A. H. Robins Company, the firm that sold the device. After paying billions of dollars in damages, the company filed for bankruptcy protection, and the whole thing became one of the most famous mass personal injury cases on record.
All this resulted in the 1976 mandate that the FDA regulate and approve medical devices, including IUDs. The Dalkon Shield’s serious design flaw was corrected; modern IUDs use monofilament strings, which pose less risk of bacteria traveling into the uterus. But the Dalkon Shield dented the legitimacy and popularity of IUDs in the United States, and its legacy is one reason the Pill has remained so popular for so long. The Pill was incredibly important for women on a personal, day-to-day level, but it was also crucial in changing society. In a word, the Pill offered women agency. It had far-reaching implications for women’s social mobility, marriage choices, and economic independence. It paved the way for droves of them to enter the workforce. It helped make it possible for women to get degrees and climb the corporate ladder without getting fired because of unintended pregnancy. It was effective, it was inexpensive, and it offered women a say over their reproductive capabilities in ways they’d never had before. For that reason in particular, the Pill took the notion of controlling one’s fertility to a whole new level.
—
More and more people are attempting to have children later in life. Across the globe, women and men are increasingly waiting until their mid- to late thirties, and even forties, to start families. One reason we’re putting off having children is that we’re marrying later. From the early 1940s through the early 1970s in the United States, women’s median age at marriage was twenty. Now it’s twenty-eight. Another reason is that women are getting more education and work experience before having children. Women with college degrees are more likely to have a child at age thirty or later than women with lower levels of education. They have children roughly seven years later than women without college degrees, using those years in between to finish school and focus on career goals.
The median age of U.S. women giving birth is now thirty, the highest on record. The average age of first-time mothers has gone up considerably in the past fifty years. In 1972, it was twenty-one. Now it’s twenty-seven. This may seem young, but it’s actually not. And in part because women are waiting longer to have their first child, they’re having fewer children overall. This isn’t a new phenomenon; the number of women who are still childless after age thirty has been steadily trending up since the mid-1970s. Since 1976—around the time IUDs improved and the Pill was deemed legal for all women—the number of women ages thirty to thirty-four who have not yet had a child actually doubled, from about 15 percent to 30 percent of all women in that age group. None of this necessarily means women aren’t choosing to be mothers; in fact, 86 percent of American women are, according to a Pew Research Center analysis of U.S. Census Bureau data.[*4] What it points to is that women are simply having children later. The phenomenon of deferring motherhood has become increasingly common in the United States over the past three decades, as birth rates have declined for women in their twenties and jumped for women in their late thirties and early forties.
The takeaway from all these statistics is that these trends—marrying later and waiting longer to have children—won’t change anytime soon. Money is one reason why: Many women delay pregnancy to hold out for a higher salary. Data compiled by a Census Bureau working paper points to an interesting fact: If women have a baby between ages twenty-five and thirty-five, their earnings take a significant hit. This ten-year window is a significant chunk of a woman’s fertile years. It’s also, of course, prime time to build a career. According to the paper, giving birth during this ten-year span—when a woman’s prime window of fertility largely overlaps with her salary-building years—exacerbates the gender pay gap. American women already earn, on average, only 83 percent of what men earn, and for Black and Hispanic women, this inequity is even greater. If biology had its way, that ten-year window—ending at thirty-five—is the age when all the women who hadn’t started having babies in the previous decade would begin. Yet it makes sense that women want to avoid getting pregnant in this period of their lives, now that they have become a permanent fixture in the workforce. And so they spend this decade leaning into their careers, breaking glass ceilings rather than breaking bread with children they don’t yet want.
Women in professional careers want to delay childbearing but are no less keen to have a child than women who opted not to delay. They delay, in part, because they want a better economic platform from which to launch their families. They wait to have children because they want to avoid what’s been called the “motherhood penalty,” the decline in earnings that I’ve just described that women can expect with each child they have, often locking them into lower incomes throughout the rest of their careers.[*5] Women don’t want to have to choose between a career and children. And so, many don’t.
These overlapping—and to some degree, competing—desires are music to the fertility industry’s ears. Because while American society has been hugely changed by modern contraceptives, the number of years during which a woman’s body can reliably bear children has remained fixed for millennia. It’s all about the eggs, remember? We cannot escape the inconvenient truth: Fertility wanes as a woman gets older. And yet. In 2021, about one in five babies were born to women aged thirty-five and older, and nearly 20 percent of women in the United States today have their first child after age thirty. Also, for nearly forty years, the proportion of American women giving birth in their forties has been on a steady rise.[*6] This, as we’ve established, is not exactly when our bodies would like to be having babies.
On the one hand: a dramatic historical shift when it comes to women having children later in life, coupled with the power of contraception. On the other: the fixed window of time a woman’s body can bear children. So how do we solve this insoluble equation? By finding ways to extend the fertility window with new technology. In the face of these demographic changes, women and men are turning in increasing numbers to assisted reproductive technology (often abbreviated as ART) to help them overcome fertility issues stemming from age and medical conditions. ART is an umbrella term for techniques that involve the handling of eggs and embryos outside a woman’s body to help her become pregnant. Hence the rising demand for medical intervention and fertility treatments for more people than ever before, and the industry that has rushed to meet it, eager to capitalize on a very real biological conundrum: As more aspiring mothers delay childbirth to climb the career ladder or find the right partner, it makes a whole lot of sense that they would also be eager to buy into what egg freezing companies are offering.
For those with sufficient means, ART helps millions of people have biological children who otherwise could not. More than nine million babies have been born from IVF since 1978. The most common ART and one of those most widely available, IVF is now considered mainstream medicine in many countries; in the United States, the number of ART procedures—mostly IVF—has jumped nearly 80 percent since 2015. The technique to unite sperm and eggs outside the body and implant them directly into the womb has been heralded, for good reason, as the most remarkable achievement in fertility to date. On IVF’s heels came egg and embryo freezing, another extraordinary advance in fertility science. As a technology focused on preserving pregnancy potential and being proactive, egg freezing, in particular, is part of this same continuum, revolutionizing how women think about not just their fertility but also their agency and reproductive autonomy.
“If women had the power to control their own bodies, if they had the ability to choose when and whether they got pregnant, what would they want next?” Jonathan Eig writes. In a culture where the optimal time to advance a career and find a life partner coincides directly with the period in which the body is best suited for reproduction, the “what next” may well be the ability to not have to sacrifice one for the other. This is what makes the idea of conquering the biological clock so powerful: that doing so is what will make it possible for women to build their careers and their personal lives when they choose to—as opposed to when their biology dictates. And so as it changes the face of reproductive decision-making, ART is ushering in the second phase of trying to have it all.
I kept thinking about Eig’s provocative question. That clause, the ability to choose when and whether to get pregnant: check. We’re all good there; bless you, birth control. It was the first bit of his question I couldn’t shake: the power to control their own bodies. A sense of foreboding lurks beneath Eig’s premise. To control their own fates, women first needed to keep from getting pregnant; then they needed to be able to preserve their fertility.
Enter Egg Freezing
In medical parlance, egg freezing is known as oocyte cryopreservation. Eggs from a woman’s ovaries are extracted, frozen, and stored on ice. Once extracted, or retrieved, the eggs are exposed to cryoprotectants—a concentrated solution of chemicals that prevents damage to the eggs when they’re being frozen—and then immersed in liquid nitrogen, where they freeze almost instantly. Cryopreservation, the freezing part, halts an egg’s processes of metabolic and genetic deterioration. Using her young eggs, a woman can theoretically carry a baby to term decades beyond the traditional childbearing years. If, after her eggs are retrieved, a woman is ready to get pregnant, her eggs are fertilized with a man’s sperm to make an embryo that’s then implanted in her uterus. That’s IVF. But if she’s not ready to get pregnant, putting her extracted, unfertilized eggs on ice affords her the option to use them if she needs to go through IVF later. Ideally, she freezes in her twenties or early thirties, although most women who freeze their eggs are in their mid- to late thirties.[*7]
The power of egg freezing lies in its potential to change the temporal limits to female fertility and buy time: time for a woman to find the right partner rather than “settle” for someone in order to meet a biological deadline, to pursue a demanding career without having to rule out motherhood later on, to figure out the family structure she wants rather than being at the mercy of fate. These aren’t the only reasons people freeze eggs (more on that in chapter 5), but for the typical young, healthy woman hoping to preserve her fertility, retrieving and storing her eggs will give her some breathing room, as well as a better shot at conceiving with her own eggs—as opposed to donor eggs—when she’s older, if and when she decides to become pregnant. Buying time is the idea, at least; I’ll go into detail about egg freezing success rates in chapter 8. First, though, let’s talk briefly about how egg freezing came to be.
In 1965, after seeing promising results freezing rabbit eggs, University of Chicago gynecologist Dr. James Burks managed to cryopreserve ten human eggs in liquid nitrogen, nine of which survived when he thawed them. While this was technically (and most likely) the first time human eggs were successfully frozen, Dr. Burks is rarely mentioned in what little literature exists on egg freezing’s history. The real story begins in the 1980s, when scientists began experimenting with different methods of freezing and thawing human eggs. In 1986, in Australia, Dr. Christopher Chen reported the world’s first pregnancy—resulting in twins—that used previously frozen human eggs. The birth came on the heels of the first baby born from a frozen embryo two years earlier, in 1984. Different sources say different things about Dr. Chen and his methods, however, and most regard his two successful cases as impressive flukes. His methods were never repeated. Meanwhile, inside a laboratory at the University of Bologna, two female Italian doctors had been quietly working to develop reliable egg freezing technology.
In the late 1980s, Dr. Raffaella Fabbri, a biologist, and Dr. Eleonora Porcu, a fertility doctor, began working together at the university’s Department of Obstetrics and Gynecology. They saw the possibility of freezing eggs as a way around freezing embryos, which troubled the Italian public—and, more importantly, the Roman Catholic Church. An embryo is a fertilized egg, and when all of a woman’s harvested eggs are fertilized in a petri dish, doctors intentionally create more embryos than can be used, to maximize the chances that an embryo made this way will successfully implant in a mother’s uterus (more on embryo attrition rates later on). There are various ethical and personal concerns when it comes to freezing leftover embryos, which often end up getting destroyed. In Italy, Spain, and other parts of Europe, religious belief made many IVF patients uncomfortable about keeping their excess embryos in a freezer indefinitely. The Church had long deemed the practice of freezing embryos immoral. Searching for an alternative, fertility doctors saw egg freezing as a way to avoid flouting the Church’s denunciation of embryo freezing. If IVF patients could freeze their leftover unfertilized eggs, they wouldn’t be forced to waste them; plus, it would be easier to discard unfertilized eggs later on, if necessary.
Fertilizing and freezing gametes (sperm or egg cells) involves fragile and difficult-to-get-right practices. Egg cells, in particular, are extremely delicate. Sperm cells have been successfully frozen since the 1950s, and human embryos since the early 1980s. But eggs, which, tiny as they are, are full of water, proved far trickier. And so despite the few favorable results early on, egg freezing remained a finicky, understudied process with meager survival and fertilization rates. Another challenge in the beginning was that other researchers at the time—and Dr. Chen, specifically—had attempted to reconstruct and reproduce egg freezing experiments but had failed to repeat their initial success.
Seeing an opportunity, the chief of Dr. Porcu and Dr. Fabbri’s lab asked them to keep working on preserving eggs. With his blessing, and without defying the Church’s anti-embryo-freezing stance, the doctors continued their experiments. Vitrification (which I’ll explain in a moment) hadn’t been developed yet, so the two women were figuring out how to improve the slow-freeze method, which relies on the balance between the formation rate of ice crystals and the dehydration rate of cells to prevent ice crystals from forming. The water contained in a human egg is difficult to expel. And egg cells must be sufficiently dehydrated before they’re frozen; otherwise, too much water will cause ice crystals to form, which can rupture cell walls, thereby resulting in genetic damage and making the eggs unusable. The Italian doctors needed to figure out a way to better dehydrate the cell before freezing it. Dr. Fabbri tried adjusting the sucrose concentration in the cryoprotectant—the substance that prevents the formation of ice crystals during the freezing process—and found that increasing the sucrose, which helps draw water out of the cell, as well as exposing the eggs to the cryoprotectant for longer, meant that more frozen eggs made it through the thawing process. Incredibly, survival rates went up to 90 percent.
