In 1999, when Poppy Hillsborough walked into work in her newly adopted home of San Francisco, she wasn’t expecting to fall in love. But then Ted Morgan, a tall, lanky Californian with sandy-blond hair and pink cheeks, held the door open for her.

“He held out his hand to shake hands and said, ‘Hi, welcome. I’m Ted,’” Hillsborough said. “I was looking into his amazing blue eyes and I remember thinking, ‘This is the guy.’ I just knew it from the moment I met him.”

It was an unwelcome realization. It was her second day in San Francisco. She was still getting her bearings, she worked with the guy, and she was already in a relationship.

The fact that Ted was HIV-positive didn’t come into play until the two started dating a year and a half later. But even that didn’t deter the dreams of pink-cheeked babies that had begun drifting through Hillsborough’s head. As a child in a Chicago suburb, she had turned spoons and forks into babies, tucking them in to the cutlery drawer with a prayer that they sleep soundly. She had always wanted to be a mother.

If she dated Morgan, she wasn’t sure how that would happen. At the time, neither did science. Back then, condoms were the best and only option for HIV prevention between those with the virus and those without (called HIV mixed-status couples). So natural conception was out, without the aid of invasive and expensive procedures. Over the next 13 years, all that would change. In 2012, the Food and Drug Administration approved the drug Truvada for HIV prevention, an approach called pre-exposure prophylaxis, or PrEP. Nearly half of PrEP users (48 percent) in the first few years of approval have been women. Poppy is one of them.

At the University of North Carolina at Chapel Hill, Dr. Myron “Mike” Cohen has four different titles in immunology, global health, and infectious diseases. His early career included research on diseases of the reproductive tract and immune system, but by the mid 1990s, he was publishing on HIV and AIDS in earnest. His work was increasingly focused on figuring out the mechanics of HIV in the blood and genital fluids, and how other sexually transmitted infections (STIs) can make people more likely to pass on the virus or to become infected.

Cohen was tackling a complex problem. The HIV virus is tricky: It targets and hijacks precisely the cells of the immune system that are designed to tell the immune system how to get rid of invading cells, hobbling the body’s ability to mount an immune response. What’s more, HIV seems to use molecules within those immune cells to hide from the rest of the immune system—what some have called an “invisibility cloak.” And even when the virus is well-controlled, it’s still present, ready to re-emerge when treatment ends.

The chance of someone passing on HIV is one in 1,000 for unprotected penile-vaginal sex and about five in 1,000 for unprotected anal sex. But people with HIV are more infectious at certain times, depending on the amount of virus in their blood and other fluids. The virus can also show up at one level in the blood (this statistic is called the "viral load") but at another level in seminal fluid and vaginal secretions. That makes it hard to track how infectious someone is.

A group of new highly-effective HIV medications—highly active antiretroviral treatment (HAART)—came out in 1995. The cocktail of drugs could slow or stop the replication of HIV in the cell, and the virus couldn’t mutate quickly enough to develop resistance to all three of the cocktail’s components at once. Here, it seemed, was a treatment that could outpace HIV, knocking the virus down before it could undermine the immune system. Scientists wondered: If new treatments can maintain lower levels of virus in the blood and the semen, does that mean that the person is less infectious? Could treatment stop the spread of the virus? Cohen wasn’t willing to make any bets without research.

Cohen began to assemble what has so far been the largest study of its kind. He found collaborators in Africa, South America, Asia, and the U.S., who recruited HIV-affected couples in stable relationships willing to submit to questions about their HIV status, STIs, and other factors. The idea was to separate these couples into two groups. In one, the HIV-positive partner would receive HAART immediately. The HIV-positive partners in the other group would get it later—when their immune function dropped, but before infection or immune system failure. The study would also try to remove variables that can increase infectiousness—by screening for and treating gonorrhea or chlamydia, for example. Couples in both groups were offered condoms and urged to use them—which, Cohen said, “they don’t, even when you ask them to.” The goal was to test the limits of HAART’s power—to see, really, if treatment could prevent transmission.

As the year 2000 wound down, Cohen and his team settled in for a long period of preparation, well aware that the National Institutes of Health, which was funding the study, could pull the plug on it at any time if it discovered that the study’s HIV-negative partners were contracting the virus at high rates.

“It was,” Cohen told me, “not at all clear to me what the results would be.”

* * *

Back in San Francisco, Hillsborough made an appointment with Morgan’s primary-care doctor, who had diagnosed him with the virus. Hillsborough wanted to know if she and Morgan could ever safely have a baby.

Morgan’s doctor sent her to the Bay Area Perinatal AIDS Center (BAPAC), a clinic within the University of California, San Francisco’s Division of HIV/AIDS, which provides counseling and care to pregnant women and their families affected by HIV. There, she received a consultation from nurse practitioner Cynthia Feakins on her options. Many, like adoption or using donor sperm, meant her boyfriend could not be the biological father of their child.

But Hillsborough was attached to the idea of having a child who shared both her and Morgan’s DNA.

She discovered that the options that allowed this were high-tech and expensive. In vitro fertilization (IVF) or intrauterine insemination (IUI) cost anywhere from $865 to $8,158 for one round, not including fertility drugs, which can run up to $5,000 per IVF cycle, according to the National Infertility Association. Then there’s ICSI, which stands for intracytoplasmic sperm injection, a process that takes IVF one step further. A scientist injects one sperm into one egg and allows it to grow before placing it in a woman’s uterus. That procedure costs about $1,500 more per cycle than IVF. All three options are available to HIV-mixed status couples only after they’ve also paid $200 or more for a process called sperm washing, which separates sperm from the seminal fluid via chemicals and centrifuge. That sperm, now “washed” of potentially infectious seminal fluid, can then be used to fertilize an egg.

There remains some debate on the safety and effectiveness of sperm washing. A woman contracted HIV in 1990 from her husband while the couple was doing sperm washing, leading everyone from the American Society for Reproductive Medicine to the Centers for Disease Control to recommend against doctors helping HIV-affected couples with insemination using the sperm of HIV-positive men. ASRM reversed its policy in 2002 . The CDC guidelines are in place to this day. It’s unclear how many clinics are willing to provide HIV-affected couples with sperm washing, but some fertility clinics claim it may be as few as 25 .

On top of that, the California legislature banned the donation of sperm from HIV-positive men in 1989—even if that donation was made specifically so a couple could “wash” it and use it for artificial insemination. So Hillsborough and Morgan couldn’t get reproductive help in the state, even if a doctor was willing to go against the CDC and ASRM’s recommendations.

Hillsborough went back to planning her life with Morgan, who would become her husband two years later. Her parents weren’t invited to the elopement in 2002, and, when they found out that their daughter had married an HIV-positive man, they boycotted the couple’s first anniversary party. Hillsborough, now Morgan, did not talk to her parents for the next five years.

* * *

Poppy Morgan was in a staff meeting in 2007 when her phone rang. She answered without looking at it; on the other end of the line was Shannon Weber, a social worker who ran UCSF’s National Perinatal HIV Hotline and Clinicians’ Network. Technically, Weber’s job was to help OB-GYNs and other physicians navigate the federal perinatal HIV guidelines and provide the highest quality of care to their HIV-positive patients. But very quickly, she had started fielding calls from HIV-affected couples and their doctors.

“Sperm washing’s not legal yet,” Poppy remembered Weber saying, “but it’s about to be.”

At this point, Poppy had talked several times with Weber, who was a source of moral support as she called clinics in Colorado, Chicago, and New York and researched services in Switzerland and Italy online.

For Poppy, then, this latest phone call was thrilling news, and not just because it could make her longed-for baby a reality; it was also good news for the couple’s bank account. The Morgans had determined that the cost of airfare, lodging, and leave from work to do sperm washing in another state would have been prohibitive—up to $5,000 per trip, plus any medications Poppy might need to increase her egg production and chances of conception.

When Poppy hung up the phone, her heart was racing.

“Oh my gosh,” she remembered thinking. “I’m going to have a baby tomorrow!”

* * *

In 2008, Pietro Vernazza, chief of the Division of Infectious Diseases at the Cantonal Hospital in St. Gallen, Switzerland, had been offering PrEP for conception to mixed-status HIV couples in which the male was HIV-positive for five years.

The treatment he offered was specific and targeted: The HIV-positive partners would have their viral load measured and both people in the couple would be tested regularly for STIs. The women would be given urine tests to monitor for spikes in a hormone that indicates ovulation. Then, when the time was right, the woman would take one pill 36 hours before unprotected sex and another the morning before sex. After, they’d come in for tests to check for HIV transmission and pregnancy. Conception rates among his patients had jumped from 40 percent for sperm washing and IUI to 75 percent for timed intercourse or timed intercourse with PrEP.

So in January 2008, Vernazza made this recommendation to Swiss doctors: HIV-positive patients with undetectable viral loads, no other STIs, in monogamous relationships, and with excellent adherence to their medications were not infectious and need not use condoms.

It came to be known as the Swiss statement.

The morning after Vernazza published his statement, Seth Kalichman, a professor of psychology at the University of Connecticut and editor of the journal AIDS and Behavior, called the World Health Organization headquarters in Switzerland.

“I called and asked them what they thought was going on,” Kalichman said. “They said they were in the middle of writing a response.” Sure enough, on February 1, WHO announced that it still recommended that all HIV-positive people use condoms to prevent the spread of the virus.

For Kalichman, Vernazza’s statement was premature. Vernazza hadn’t published any of the data from his work with HIV-mixed status couples. He hadn’t conducted a trial like the one underway at the University of North Carolina. Researchers like Kalichman, or the HIV doctor down the street, had no data on which to base a change in practice that would conflict with the CDC’s ban on unprotected sex for HIV-positive people.

“It was going to be easily misinterpreted by the masses,” Kalichman said.

Kalichman lived in a very different HIV world than Vernazza and his highly compliant, monogamous couples. He spent his days working with HIV-positive people who scored high on the sexual compulsivity scale he had developed, on one hand, and paranoid AIDS deniers, on the other. His book, Denying AIDS: Conspiracy Theories, Pseudoscience, and Human Tragedy, would come out the following year.

Kalichman has spent the last seven years studying how well people with HIV stick to their treatment regimens. Verdict: not well. They feel good, so they don’t take their medications. They have substance abuse or mental health problems, so they don’t take their medications. Or they simply forget.

“If you meet the criteria of the Swiss statement, what the statement is advertising is true. The problem is, it only applies to a very small minority of people,” Kalichman said. “Most people with HIV infection don’t know they have the infection. If they know they are infected, they aren’t necessarily accessing treatment. Those that are accessing treatment are not necessarily adherent. Those who are adherent often will have an undetectable viral load, but that doesn’t mean it’s undetectable in the semen. And it’s not just another STI that increases the chance of transmission. It’s any inflammation in the genital tract.”

Vernazza disputes Kalichman’s argument about lack of data, saying that he based the Swiss statement not solely on his own patients, but on literature that showed there had been no HIV transmission in HIV-discordant couples when the HIV-positive partner’s viral load was undetectable.

Back at UNC, meanwhile, Myron Cohen wasn’t prepared to share his protégé Vernazza’s optimism. At the time, Cohen was three years into the pilot study for his clinical trial. It had taken five years to set up, and hundreds of people in Brazil, India, Thailand, Kenya, Zimbabwe, Malawi, Botswana, South Africa, and the U.S. were being monitored.

At an event before the International AIDS Conference in Mexico City later that year, Cohen said of his study, “We have an HIV epidemic, and suggesting that some people with HIV can have sex without a condom will only create confusion and make it worse."

“Pietro will tell you that he knew what the results of my study would be,” Cohen told me. “But I didn’t know. How is it that he could know the results of my study when I didn’t?”

* * *

Poppy Morgan didn’t know anything about the Swiss statement. All she could think about now was sperm washing: The California legislature had finally overturned the ban on HIV-positive men donating sperm. She could finally have the procedure and, maybe, get pregnant.

And so it was that she found herself sitting in her doctor’s office, listening to him explain what would happen next.

“How it will work,” she remembered her doctor saying, “is that your husband will give me his sperm sample, we’ll send it to New York—”

“Wait, whoa,” she interjected. “Why are you going to send it to New York when sperm washing is legal here?”

Her doctor explained that there were no guidelines from the CDC on how to proceed with sperm washing. California doctors were free to counsel and work with patients on sperm washing—but few clinics in the state were willing to do the procedure themselves.

As Poppy listened, the doctor explained that Ted’s sperm sample would be frozen and sent to New York. There, it would be thawed, processed and then refrozen, shipped back to California, and thawed again.

Then another sickening thought occurred to her.

“Wait a minute,” she asked. “After all that freezing and thawing, what’s the likelihood that the sperm will be viable?” Her husband’s HIV medication already reduced his fertility.

“There’s a very low chance of viability,” the doctor replied.

Poppy burst into tears.

“What’s the point?” she asked. “’If it’s not even going to be viable, what’s the point of all this?”

This article has been excerpted from Heather Boerner's Positively Negative: Love, Pregnancy, and Science's Surprising Victory Over HIV.