ONE OF HEIDELISE ALS’S early memories is the sound of Allied bombs exploding, a consequence of being born in Krumbach, Germany, in 1940. Another is being forced from her family’s home when American soldiers confiscated it. She remembers the cramped attic apartment her parents moved to with their three small children, and the sharp thwack when the couple who lived downstairs rapped a broomstick on the ceiling because a child was making noise.
For years after the war, things did not get better. But looking back, Als can see how those early experiences formed a foundation on which to build a career. “The war, and especially the postwar years,” she says, “mainly prompted me to question how people developed their emotions and their character.” She would go on to advocate for the most fragile group of all: premature babies.
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Als, a developmental psychologist at Boston Children’s Hospital, has spent decades researching newborns, along the way remaking how infants are cared for in her hospital and others. The difference between the newborn intensive care unit at Boston Children’s now, and the one expected to open in 2022 as part of the new Hale Family Building, reflects the impact of her findings.
The current ICU, brought into service in the late 1980s, can feel as active as an airport. Its rooms include four private, one semiprivate, and a fourth that can hold up to 24 babies at one time. Families are assigned to the more private rooms not because of need but when the rooms happen to be open. Until last year, when individual lights were added, there was just one light switch for the whole group room, so checking on one baby potentially meant disturbing all of them. It was a setup that was designed around the needs of doctors and nurses.
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In the new building’s design, the infants come first. Babies in intensive care will have a private room with muted lighting and space for their families. This will encourage parents to spend as much time as possible with their babies, learning how to attend to the infants they will soon have to care for on their own.
> Related: For more on Boston Children’s 150th anniversary, click here.
What Als’s research helped establish is that busy, brightly lighted maternity wards aren’t the best for babies, and in particular for those born prematurely. Modern medicine can now keep alive children born after just 23 or 24 weeks in the womb. In babies that young, their developing brains will be compromised, which can lead to developmental disabilities and long-term physical and mental health problems. In the 1970s, Colombian doctors who lacked incubators for premature babies had parents hold their preemies on their chests, acting as a kind of living incubator. It turned out this “kangaroo care” greatly increased preemie survival rates. Als showed that such care also leads to noticeably different brain structures and measurably improved brain function: By the time they are 8, babies who received kangaroo care can concentrate, organize their thoughts, remember more, and function better than those who didn’t. Als says this shows that no incubator can substitute for human care.
Als has also shown that preemies can communicate with us, if only we know how to listen. It isn’t easy, she admits, when diapers need changing and the inevitable crisis arises. But “it often doesn’t take much,” she says. “It takes standing next to someone and bringing down the stress, so the hands are soft and the baby relaxes and the mother blossoms. . . . It’s wonderful to see when it happens.” As a researcher, she adds, “that’s what you’re really in the field for.”
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It’s a field Als has fundamentally shaped. As one of the first to focus on the developmental care of premature babies, her research “has really changed our focus and our understanding of how to take care of very preterm babies,” says Dr. Eric Eichenwald, chief of neonatology at Children’s Hospital of Philadelphia. He worked with Als when he helped run neonatal intensive care at Brigham and Women’s Hospital, where she conducted some of her many studies.
But even after her decades of work, Als says it is still a challenge to persuade busy doctors and nurses to change the way they work. She wants them to slow to a newborn’s pace, to know that the noise they make and the light they shine on babies disturbs them, to know that small changes in how they work can make a world of difference to the developing brain.

AS A YOUNG WOMAN, Als spent a year teaching elementary school in Germany, before she married an American and followed him to Philadelphia. There, she started a master’s degree in education and developmental psychology at the University of Pennsylvania. While working on her degree, she became pregnant, and in 1965 gave birth to a baby who would be her only child, a son. He had big, beautiful eyes, but was challenging — screaming, crying, having trouble settling. He had a seizure disorder, and, she learned decades later, a brain that had more folds than it should have, which led to significant developmental disabilities (today he lives in a supported environment).
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Her infant son reinforced the idea that babies could communicate their needs — if adults would only listen. “I learned from him to observe him and believe what he’s telling me,” she says. “I learned that he influences me in many ways more than I influence him.”
The idea that babies influenced mothers — rather than solely the other way around — defied conventional wisdom in the 1960s. In those days, mothers were blamed for everything their children did and everything they became, even when they developed autism. Als always found this assigning of blame stupid — she uses a stronger word — and it didn’t match her experience as a researcher or as a mother. And subsequent research has proved her right.
For her doctoral thesis in developmental psychology, Als sat in on 100 full-term childbirths — fathers weren’t allowed in the delivery room then, but she was. She sometimes held the woman’s hand during labor, but shifted into research mode as soon as the mother met the baby. Taking notes every 15 seconds, she watched as the mothers removed the swaddles around their babies and interacted with them for the first time.
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At one point during her research, the hospital’s medical director called her into his office, and in a stern voice asked what she was doing with those women. She braced for criticism, but he was curious, not angry. “It seems they are doing really well in their deliveries,” he told her. Why was that? To Als, it made perfect sense. Of course a mother would fare better with a sympathetic person at her side.
After getting her PhD, and a divorce, Als went to England for a year for further training. She published her first paper in 1972. The next year, she was hired to work on child development research at Boston Children’s by Dr. T. Berry Brazelton, the pediatrician who later gained international fame as an author and television star. Brazelton became a mentor — “He was so skilled in observing full-term, healthy babies,” Als says — and she focused her research on newborns who needed intensive care.
Als has gone on to publish more than 150 research papers. Many of her early journal articles were collaborations with Brazelton. Since the early 1980s, she has frequently collaborated with her second husband, Dr. Frank H. Duffy, a Boston Children’s neurologist. In addition to her seminal work in effective newborn care, Als has written studies about subjects as diverse as the behavior of premature babies, the (limited) value of playing live harp music for newborns, and the importance of teaching simple developmental care to caregivers in developing countries. At 78, she is still an active researcher; her most recent publication was in February.
Her output has completely redefined her field, says Samantha Butler, a clinical and developmental psychologist at Boston Children’s who has collaborated with Als. “She’s the one that brought all of this into people’s minds: that you can read an infant’s behavior and change the environment to support them, and improve their long-term outcomes.”
Als, though, is not satisfied with acknowledgments, and has no interest in accolades for her published work. “It’s no good if it just sits in journals,” she says. She wants hospitals to put her ideas to work in their neonatal intensive care units.

EARLY THIS MONTH, Als, Butler, and Emily Serino, a Boston Children’s neonatal intensive care nurse, are standing alongside an open incubator in one of the semiprivate rooms. They are watching 2-week-old McKenna, who was born at 33 weeks. All three take notes as McKenna squirms, stretches tiny fingers, loses her pacifier, and squawks weakly — coping with the world is still difficult. The three observe as a nurse, a doctor, and then a nurse in training interact with the baby.
Afterward, the three women find an empty office and talk about what they’ve seen. They discuss the noise in the room, whether outside voices were audible, phones were ringing, monitors were sounding. Was there too much sunlight shining into the crib? What was the environment like on the floor? Over nearly five hours, they analyze the baby’s strengths, her challenges. The nurse, they agree, was attentive and empathetic. “As a parent, if anyone is talking like that to your baby, you would feel good,” Butler says. “This person really cares about your child.”
But Butler also notes that the nurse seemed to overlook McKenna’s breathing problems. “I don’t think she understood that whole pattern and why she was becoming unsettled,” she says. “That’s what McKenna is trying to tell us: ‘I’m having trouble with my breathing.’ ”
Als interjects, gently, asking how Butler might recast her criticism in a more positive way. There’s a lot happening in an intensive care unit, and medical professionals don’t need to hear they’re doing things wrong. They need to hear how they can improve.
Butler rephrases: “McKenna is showing her discomfort and difficulty with breathing, which can be challenging for a caregiver to appreciate.” Als approves, then notes the baby was reacting more slowly than the nurse was moving. “They seemed to get out of synchrony,” Als said. “The nurse kept at a pace that was different than the baby’s.”
For Serino, it’s a moment of recognition. “We’re moving at grown-up speed,” she says, “and the baby is working at 35-week speed.”
The day is part of the training program for what might be Als’s most important work — she was the first to develop a comprehensive method to incorporate new ideas in research and teach them to others. She introduced the system to train nurses — it’s known as the Newborn Individualized Developmental Care and Assessment Program, or NIDCAP — in the mid 1980s.
Serino’s been a neonatal intensive care nurse at Boston Children’s for 12 years, and was confident in her abilities before she started Als’s year-long training course. But she was amazed by Als, who could look at a baby and predict what he or she would do next. “I was like: How did you know that’s what was going to happen?” Serino recalls. Now that’s she’s nearly completed her training, Serino can also correctly interpret a baby’s signals and patterns to make the same kind of predictions. Part of it is about going beyond what a baby’s medical needs are, to ask, “What does the baby want?”
Als’s system has spread around the US, Canada, Europe, Australia, and the Middle East. There are some two dozen NIDCAP training sites, and about 1,000 nurses are certified. Once trained, nurses are expected to spread the ideas around their intensive care units. Still, it costs $30,000 to train a nurse, not including the time away from his or her duties while learning and training others. Many hospitals that have adopted NIDCAP are in Europe, particularly Scandinavia, where newborn care facilities are well staffed and parents have extended leaves from work so they can support their babies.
Als says her approach actually saves hospitals money, because babies spend less time in the hospital and need fewer services as they develop. “But it needs money upfront,” she says.
Most hospitals do deploy some elements of her program. Eichenwald at Children’s Philadelphia, a proponent of Als’s ideas, says he finds the time and expense of her newborn developmental care program off-putting. He advocates what he calls “NIDCAP light,” where intensive care units adopt some of Als’s principles, without the full training program.
Als, in her blunt fashion, says she thinks such half-measures are shortsighted. But on the verge of turning 79, she is starting to think about her next phase of life; she is stepping off the NIDCAP board, and isn’t sure she will apply for new research grants when her current set ends next year. She is the only person in Boston currently certified as a trainer in her newborn care approach, so she is training Butler to succeed her as a trainer at the hospital.
Her passion hasn’t dimmed. “The work is a big part of my life,” she says. “I like to see it grow and I like to see the babies do well and the parents do well.”