When the call came, my brother was at work in the open office in Cambridge, Mass., he shares with seven colleagues who, like him, help run clinical trials for a drug developer. The phone number came up blocked, so he knew it must be the doctor. He stood up, unsteady on his feet. Was he a little nauseous? Or was that just adrenaline? He ducked into the hallway in search of quiet.

My brother Evan, 35, is a stocky guy of medium height with a trimmed, fuzzy blond beard and two gem studs in each earlobe. He usually wears a Red Sox hat, and when he's nervous, he'll remove it and obsessively bend the rim. But on that September afternoon, both of his hands were clutching his phone, the right one cupping the left for privacy. "Hello?"

"This is Dr. Kowalik," said the voice. The identification was unnecessary. Ania Kowalik is a reproductive endocrinologist at a clinic called Fertility Solutions in Dedham, Mass. They'd spoken regularly for more than six months. Evan, who was born female, had wanted to be a parent since he was very young, when he played with dolls just a bit longer than the other kids. He'd helped pay for college by nannying triplets. And when he first came out to friends as transgender at 19, changing his name and beginning his long physical transformation, he didn't stop adding to the list of baby names in the back of his journal: Kaya, Eleanor, Huxley.

Evan knew he should feel excited. But instead, he felt a chill of anxiety and anticipation. He'd wanted this for so long, he later told me, and had been close to getting it. Then, four months earlier, he'd miscarried after Kowalik told him she couldn't find a heartbeat during his first ultrasound.

She was brief: Evan was pregnant. Kowalik told him he had low levels of progesterone, a hormone that helps maintain a healthy pregnancy, and prescribed some pills for him to start taking right away. "Congratulations," she said after a pause. "This is a good start."

Evan isn't sure how long he stood in the hallway after the call. People from other offices brushed by him, caught up in their work. He called his partner, and her gasp was loud enough that Evan held the phone away from his ear momentarily. He pulled up a calculator to figure out his due date.

I'd have no reason to tell you about this moment in my brother's life were it not for the fact of his gender. Now that gay marriage is legal, the social battleground has shifted to new frontiers, frontiers that include the most private aspects of people's lives. Transgender Americans have gained greater visibility and acceptance as stars like Caitlyn Jenner and Laverne Cox have trained a pop-culture spotlight on trans issues. Corporate leaders across the Fortune 500 have moved to protect their transgender employees. And in May, the Obama Administration declared that all public schools must treat students equally regardless of their gender identity, classifying inner feelings of maleness and femaleness as protected by the government. We have come to the point where the President of the United States can candidly and comfortably discuss gender fluidity.

We have also come to the point where the backlash against these rapid changes has manifested in sometimes surreal fashion, as it did earlier this year during the so-called battle of the bathroom, when about half of all states joined lawsuits against the Obama Administration. There have been reports of increased violence directed at transgender people. At least 21 trans Americans were murdered in 2015, according to the Human Rights Campaign, up 62% from the year before. And that was before the mass murder in June at an Orlando nightclub, the deadliest incident of violence against LGBT people in U.S. history.

Pregnancies like Evan's—and the many that are likely to follow—will stretch our cultural perceptions of gender norms even further. Americans are just starting to open up to the idea that you may be born into a female body, but believe that you are really a man. But what if you are born into a female body, know you are a man and still want to participate in the traditionally exclusive rite of womanhood? What kind of man are you then?

This question can bother people. It can make them uncomfortable. That's partly why, when Evan texted me to say, "I'm pregnant!" I was excited for him, but also frightened. I thought about what strangers might say to my bearded, big-bellied little brother when he was nine months along. And I wondered, Would he be safe?

Evan stopped Testosterone treatment in order to get pregnant. Elinor Carucci for TIME Evan stopped Testosterone treatment in order to get pregnant.

Elinor Carucci for TIME 1 of 4

I am six years older than Evan. We also have a middle sister, Katje. As a trio, we've always resembled one another, but Evan and I were the most alike. We still have the same patterns of speech and the same slight roll to our shoulders that we inherited from our grandmother on our dad's side. Once, when Evan was in college at Oberlin and I was in grad school at the University of California, Berkeley, he flew across the country to visit me. When he got off the plane, we were both wearing the same thing: puffy down vests over long-sleeved ultimate-frisbee T-shirts and baseball caps worn backward.

By then, my brother had already come out to himself and friends as trans, but he didn't tell me until 2003, when he started taking hormones. He called me to say that when he came for my graduation, I should call him Evan.

Over the next few months, I watched his body change. He started binding his chest with a thick bandage wrap. His hair began to thin. His hips disappeared and were replaced by thick muscles around his chest. But mostly, I remember his hands. We both have the same small hands, the same indelicate, stubby fingers. I watched the hair grow thick over his knuckles, which were my knuckles. I felt sad that, feature by feature, I was losing my doppelgänger.

The transition was messy. Our parents were supportive but distracted. They were in a protracted divorce after my father had, at 50, come out as gay. Katje and I dated women, and I would kid Evan that being gay wasn't rebellious enough in our family; he had to do us one better and change gender. Looking back, I regret these jokes. They were a crass way to cover the pain of knowing that the childhood we all shared--the one in which we were three round-faced, pigtailed girls in matching dresses--had been a charade for my brother.

I said the wrong things all the time. That first year Evan looked strange to me, like a butch lady or a girly man. He went through a sped-up version of puberty that brought changes to his voice and testosterone-fueled impulses he didn't understand. I often she'd him by accident. I'd forget and call him by his given female name, or refer to him as her. And in an attempt to sound interested and supportive, I asked him invasive and personal questions, often in mixed company. Once, during a brunch with our extended family, I asked him about whether he planned to alter his genitals. "Jessi," he said, raising his right eyebrow in that way we both do. "I don't talk about your vagina in front of Aunt Rosie."

Thirteen years later, no one mistakenly she's my brother. Physically, he is transformed. He's 5 ft. 6 in., just tall enough that he makes a respectable short guy. Before his pregnancy, he injected hormones into his thigh once weekly to lower his estrogen while boosting his testosterone. He elected not to have top surgery, the double mastectomy that many trans men undergo, because he is allergic to most antibiotics. Also, he knew he might one day want to nurse a baby. So he wears two compression-tank binds made by a company called Underworks beneath his shirt. "It hurts, but I've gotten used to it," he told me. "I imagine it's like some women getting used to high heels."

We have come to the point where the President of the United States can candidly and comfortably discuss gender fluidity.

His transformation is as much social as it is physical. It's not just that Evan looks like a guy. For nearly a dozen years, the world has responded to him as a guy. At first, particularly when he was with other men who didn't know he was trans, this made him nervous--like he would somehow say the wrong thing and out himself. But now he's comfortable. To medical professionals, he's a trans guy, but to the rest of the world and to himself, he's just a guy.

In 2013, when Evan made an appointment with his primary-care physician at the Boston LGBT health center Fenway Health, he was the first prospective birth father his doctor had seen. Several years earlier, a few trans men who, like my brother, had undergone hormone treatment but kept their reproductive organs, had begun consulting physicians about pregnancy and speaking openly about wanting to give birth. In 2008, Thomas Beatie posed for People magazine, bare-chested with a rotund belly, and went on Oprah to talk about his pregnancy. Trans men began to trickle into fertility clinics more frequently. When Andy Inkster was turned away from a Massachusetts clinic in 2010 because he was told he was "too masculine" to have a baby, he sued for gender discrimination. The case settled a few years later; Inkster sought out another clinic and later gave birth to a daughter.

What happened to Inkster is not uncommon. Medical care of all kinds is complicated for trans Americans. Roughly 1 in 5 have been turned away by a medical professional at some point, according to the National Transgender Discrimination Survey. Published in 2011 by the National Center for Transgender Equality and the National LGBTQ Task Force, it is one of the largest surveys about trans people, with 6,456 respondents. Half of them reported that they'd had to teach the medical professionals they visited how to treat them. That's why, until my brother tried to get pregnant, he mostly avoided doctors.

There is very little research about trans pregnancies. One of the only medical papers addressing the topic was written in 2015 by the University of California, San Francisco's Dr. Juno Obedin-Maliver and Harvard Medical School's Dr. Harvey Makadon. They noted that, in form and function, getting pregnant as a trans man is not that different than getting pregnant as a woman. Most of the time, trans men stop taking testosterone, and their bodies begin ovulating again. (Testosterone doesn't necessarily preclude a pregnancy. Some trans men may have unintentional pregnancies while taking it.) If their partner is biologically male, trans men may try to conceive without medical intervention.

My brother has a female partner, so he inseminated using donor sperm. It took a while. The first time Evan tried, five years ago, he was unsuccessful. He took a break before starting again three years ago. He stopped his T shots, Kowalik prescribed two medications to trigger ovulation and monitored Evan's body throughout the process to get the timing right.

Evan estimates that the entire process, including medication, doctor visits, co-pays and ultrasounds, cost him close to $12,000 over the course of several years. That's expensive, but it can cost much more. If home insemination doesn't work, trans men may turn to other fertility treatments, like in vitro fertilization. Each round of IVF costs an average of $12,400, and often, by that point, aspiring parents have already invested a considerable sum in earlier, unsuccessful methods.

If the physical process of getting pregnant is fairly straightforward, transgender birth parents often face more challenges when it comes to mental health. Obedin-Maliver and Makadon referred to two recent studies that highlighted psychological issues involved with trans pregnancies. In both cases, the sample sizes were too small to be statistically relevant, but significant themes emerged. For one, the birth parents were often lonely. And they reported complex feelings about their gender identity. "While having a family is something that many transgender individuals want, pregnancy can lead men to acknowledge that they still have female reproductive organs, which for many can be difficult, however rewarding the pregnancy may ultimately be," they wrote.

My brother has a good friend, also trans, who'd gotten pregnant a year earlier. He'd had a rough pregnancy because he felt a traumatizing disconnect between his masculinity and the female attributes of his body. He took medical leave from work for much of the time and was relieved to restart testosterone immediately after his child's healthy birth. I spoke to another trans dad who had given birth to his son at age 20. He said the pregnancy catapulted him into depression. "It was as if all the things I'd hated about my body were re-emerging, and I felt awful about myself," he told me. Evan didn't have this experience. "It was a gamble," he said. "I didn't know how I'd feel, but it turns out I just feel like it's really cool that my body can do this."

Evan estimates that the entire process, including medication, doctor visits, co-pays and ultrasounds, cost him close to $12,000 over the course of several years.

When I called Obedin-Maliver to discuss the research, she cautioned against drawing any conclusions about trans pregnancies based on a few conversations. "Take two pregnant women and their experiences will be different and we don't ascribe that to their womanhood," she said. "We have to be careful about that and not say there's one trans-man experience going through pregnancy."

Trans men compare notes among themselves and seek support and advice on the Internet. My brother and I belong to a private Facebook group called Birthing and Breast or Chestfeeding Trans People and Allies. It has about 1,780 members. A list of guidelines spells out who can join the group: "People on the transfeminine spectrum, those who are genderfluid, nongender folks, transmasculine individuals, and cisgender allies." (I am cisgender. This means that my self-identity conforms to the gender of my biological sex. I was born a girl, and I feel like a woman.)

My brother turns to this group when he has questions about chest-feeding--the term trans men have adopted for nursing--or choosing a trans-friendly pediatrician. For many members, it is a primary source of community. One trans dad told me he believes he would have killed himself during the early months of his pregnancy if he hadn't found friends through the group."When I went off the hormones [to get pregnant], all the mental-health stuff I had as a teenager came back," he told me, referring to a time in his adolescence when he was deeply depressed. "My online friends were the only people who got me."

Just how many trans people have given birth? I asked Makadon, who is also the director of education and training at Fenway Institute, a division of Fenway Health. He couldn't even guess, but he said he expected to see the numbers rise based on the increasing number of trans patients coming to the clinic. Fenway currently sees more than 2,000 of them, a figure that has doubled in less than a decade. He said that, as he visits hospitals across the country, he hears a lot of stories about health providers treating pregnant trans men. "There's more of it than we know that people aren't tracking," he told me. "There's a lot of people just doing it."

As doctors prescribe hormones, it is becoming standard practice for them to talk with patients about reproduction. "We get questions about cryopreservation," says Obedin-Maliver, referring to the process of freezing healthy eggs. Although there's no data to suggest that regular testosterone treatments will prevent trans men from growing healthy eggs later, some of them elect to do this before starting testosterone treatment. Says Obedin-Maliver: "Trans men want to know what their options are."

During my brother's first trimester , he only wanted to eat Fla-Vor-Ice pops, Sour Patch Kids and hard-boiled eggs. He threw up constantly. Normally, Evan worked until 7 each day, came home for dinner and then answered a few more emails before bed. But once he was pregnant, his body stopped cooperating. At 8:30 p.m., no matter where he was, he fell asleep. By November, he could tell his supervisor had started to wonder why he was "slacking off." It was time to tell his employer.

During his next trip to his company's Oxford headquarters, Evan scheduled a meeting with the woman in charge of human resources. That morning, he found himself in an office with an open plan; even the conference rooms had glass on three sides. He had just vomited in the bathroom. He tried to fight his nausea as he saw the HR lead approach. She was a short woman with a high voice and a warm demeanor who, Evan thought, was more or less his age. He straightened his tie and followed her into an exposed conference room.

Evan took a moment to center himself, to quell his anxiety. There would never be an easy time for this conversation. He had to get it out. "It wasn't that I expected her to have a negative reaction," my brother said. "I just had no idea at all."

He told the woman he wanted to share some personal information. "I am transgender, which you might know because of my health care paperwork," he said. Paperwork, according to my brother, is how many transgender people are inadvertently outed in the workplace. An employer will send a letter to Social Security or to the Internal Revenue Service to verify a new hire's personal information; the agency will respond that the wrong gender has been listed. (Evan's friends call this a "no-match letter.") Evan had lived with the possibility that at any moment this could surface, since he'd started the job six months earlier. Maybe this woman had known he was trans all along, he thought.

It turned out she hadn't. She nodded as he spoke and didn't seem fazed. She asked why my brother was bringing it up. "Well, I'm pregnant," he told her. A moment passed. Then, bit by bit, her face broke into a smile. "Well, this is unexpected, but that's great!" she said, and the tension flooded from my brother's shoulders. She told him about her two little girls and how wonderful parenthood was. My brother sat there with her, talking about spit-up and dance recitals, and he remembers feeling like part of a club he'd always looked into from the outside. The normal things that happen to normal parents would be his things, he thought.

For the most part, this is how it went when my brother told people he was expecting. "With most folks, I phrased it, 'Well, you know my partner and I are having a baby, and it works best for our family that I carry the baby,'" he told me. It usually took them a few minutes. Then, as best they knew how, they said supportive, kind things. Our mother started knitting a sweater for the baby. His dermatologist said, "That makes all the sense in the world." When he finally screwed up the courage to tell his supervisor a few weeks after his Oxford trip, she asked how she could be supportive.

Evan took a moment to center himself, to quell his anxiety. There would never be an easy time for this conversation. He had to get it out.

This positive attitude is less surprising when you consider that my brother didn't tell many people he didn't know well. He didn't need to. Even at full term, he never looked pregnant. He looked like a guy with a beer belly. He wore collared shirts to work, often with sweater-vests, and when he couldn't button the shirts any longer, he bought bigger ones. When his pants stopped buttoning, he wore them lower and got suspenders. "People talk about the attention you get when you're pregnant, and for the most part that was absent for me," he said. No one rubbed his belly, asked when he was due or commented that he was carrying the baby low so it must be a boy. "Mostly I liked that, because I don't like body attention normally," he added, "but there's also a loss."

One April afternoon, when Evan was< in his eighth month, he stopped by Goodwill to sift through baby clothes. He took a few outfits to the counter. Evan opened his wallet, and the woman behind the register noticed the small ultrasound snapshot he kept tucked inside. She looked at his belly, and smiled at him. His blood ran hot. "That felt incredible!" he said. "She read me! She got me."

Evan's midwife was Clare Storck . Really, that's her name. She'd been catching babies for five years at a practice attached to Mount Auburn Hospital in Cambridge, but she'd been working with expectant mothers for most of her adult life as a doula. My brother was her first male birth parent.

When Evan arrived at the midwifery center for his first appointment, he filled out an intake form, but the receptionist had trouble entering his information: if she checked the "male" box, she couldn't open an obstetric record for him. This was a problem throughout the pregnancy--medical forms and insurance claims are not set up to allow people like Evan to be honest about their medical needs.

At first, he fought this at every turn. When his health insurance refused to cover his pregnancy test because he was male, he spent several hours explaining his situation to a representative, waiting on hold and explaining it again. "My sex is female, and my gender is male," he told the rep. She was able to override the system and get the cost reimbursed, but he had to call back and do the same thing every time he had an appointment.

Eventually, Evan decided it wasn't worth the effort to fight weekly for coverage. He called his insurer and asked that his gender be changed to female. "When I get insurance letters, they don't say 'sir' or 'ma'am.' They say 'Dear Evan Hempel,' and that's just fine. At the end of the day, it was just frustrating to get denial after denial of services," Evan said.

Despite the initial software limitation, my brother got excellent care from the midwifery practice at Mount Auburn. Practitioners had received some training from Makadon, who had visited recently from Fenway to lead a grand rounds--an hour-long lecture open to anyone on staff at the hospital--on trans births. They shared notes on Evan's preferred gender pronouns and terms for his body, and he had regular appointments with Storck, who listened to his baby's heartbeat, checked in to see how he was feeling and referred him to an acupuncturist when he developed back pain.

Several weeks before the birth, I interviewed Storck, who has an ebullient personality, about her experience treating Evan. She was supportive of my brother's choice to get pregnant. We both marveled at the technological advances and social changes that have enabled my brother's efforts to make a family. "If physiologically your body can do this, and you're comfortable with the process and still want to present as a man, you can," she said. "And that's awesome."

My nephew arrived on the day he was expected. "I'm not sure he's mine," my brother texted from the hospital. "I've never been on time to anything in my entire life." Six days later, my partner and I drove to Boston to meet the baby. When we arrived, Evan had just finished chest-feeding. He answered the door in pajama bottoms and a nursing tank, with the baby swaddled in the crook of his right elbow. Evan handed my nephew to me, and right away, the baby began squalling, his mouth gnawing at my arm. I handed him back to my brother, who gestured for all of us to sit at the big wooden kitchen table and then started chest-feeding again.

If physiologically your body can do this, and you're comfortable with the process and still want to present as a man, you can. "And that's awesome."

We sat there like that, in the kitchen of my brother's second-floor apartment, munching on the lemon bars my mom had made, as the summer daylight stretched into evening. The baby ate and slept and ate some more, his right arm curled up to his chin. Evan recounted the birth, giving us a blow-by-blow. He and his partner had arrived at the hospital just after midnight, he said, and as they lumbered toward the receiving room, a nurse passed them. "Can you imagine what she must have been thinking?" my brother asked. Here were a woman and a man walking toward the maternity ward. The woman was weighed down with suitcases, a backpack and the paperwork folder. The man carried nothing but a purple yoga birthing ball, and every few steps, he'd push it up against the wall, lean over it and moan. Evan snickered, and soon we were all laughing at the thought of it.

I asked Evan if childbirth had changed how he thought about his gender. Wasn't there some part of him that questioned his masculinity? Since he'd first come out, I'd watched him challenge our binary notions of gender--male or female, boy or girl, husband or wife. And yet I still had questions. Were you always a boy trapped in a girl's body, I wanted to ask him, or are you really a girl who got lost for a decade? "You know, people who are not trans talk about being 'trapped in a body.' But that's not really the way my friends talk about it," he said. "I was always Evan. I always had these parts. I always just felt like me, and like I was a guy."

As I puzzled over this, he gulped milk from a glass with a blue sea horse on it. There are sea horses all over their home--on onesies and bibs, in drawings and stitched on blankets. It has become Evan's emblem, because like my brother, the male sea horse gives birth after carrying eggs in a protective pouch on his belly. A sea horse's masculinity is not threatened by gestation; it is reinforced by it.

Evan will continue to chest-feed for a while. Eventually, he'll begin taking testosterone again. His beard will fill out, and the fuzz will return to his knuckles. His chest will shrink to the point where his bind will be comfortable to wear again. To outsiders, his family will look like any other--a tossed-together group of kids and adults raising one another. At night, my brother will watch his son lift a tiny fist above his head as he sleeps and know what all parents know: this baby is a miracle.