T. Berry Brazelton, a pediatrician whose best-selling guides to child-rearing soothed generations of parents, assuring them that they need not seek perfection and that the answers to many of their questions lay before them in their children’s behavior, died March 13 at his home in Barnstable, Mass. He was 99.

His daughter-in-law, Jennifer Brazelton, confirmed the death but did not provide a specific cause.

Dr. Brazelton was perhaps the best-known American pediatrician since Benjamin Spock, who revolutionized child-rearing by counseling parents to rely on their “own common sense” rather than on commandments dispensed by purported experts.

Dr. Brazelton — who described Spock as his “hero” and who counted Spock’s grandchildren among his patients — picked up where the older physician left off. In books such as “Infants and Mothers” (1969), in his hit “Touchpoints” book series, in commentaries published in Redbook and Family Circle, and on the Emmy Award-winning television show “What Every Baby Knows,” Dr. Brazelton genially coached parents to see their children’s abilities as well as their own.

He bucked prevailing notions of his time by arguing that babies are not “lumps of clay” but rather expressive beings whose behavior conveys their needs. Rather than instructing parents on child-rearing, he sought to help them read their babies’ cues.

“People assumed babies were all the same and that it was parenting and the environment that made the difference,” Dr. Brazelton told USA Today in 2013. “We were blaming parents for everything that went wrong with babies. I thought if I could assess these babies early . . . we could use this in understanding the child more and give the parents a better chance of understanding the child, too.”

Dr. Brazelton spent much of his career in Massachusetts, where he held appointments at Harvard Medical School and Boston Children’s Hospital and where he maintained a private pediatrics practice in Cambridge.

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In 1973, he developed the Neonatal Behavioral Assessment Scale, often called the Brazelton. The now widely used test relies on simple tools such as popcorn kernels and a pocket flashlight to test a newborn’s response to sound and light. He identified three broad categories of babies: average, quiet and active.

Besides helping new parents decode an infant’s needs, the test changed adoption practices by allowing physicians to quickly gauge a baby’s health. Traditionally, babies awaiting adoption were institutionalized for months of observation before placement. Dr. Brazelton contended that neither children nor their adoptive parents could afford to lose those critical early months of bonding.

Although the scale was widely regarded as one of Dr. Brazelton’s most significant contributions to medicine, his reach extended far beyond hospitals, into homes and the most intimate decisions parents make. On his television show, he was said to project a “combination of Sigmund Freud, Mister Rogers and Phil Donahue.” Mainly, he tried to persuade parents not to worry so much.

“Parents care so much they can’t smile,” he told an audience in 1979. “They can’t smile and give children a feeling of the excitement of being a parent. I would like to look at what can be done to get parents to relax and not to take [parenthood] quite so seriously.”

He assured those with picky eaters that “children always eat better for people other than their mothers.” Neither should bickering cause parents too much consternation. “Fighting,” he observed, “is how siblings learn about each other.”

He especially sought to comfort strung-out mothers.

“Parents are surprised and even ashamed at their own lack of endurance with small children,” he wrote. “But they needn’t be. There is nothing so exhausting as giving attention constantly to someone else.”

Dr. Brazelton was known particularly for a series of books, beginning in 1992, on developmental milestones that he dubbed “touchpoints” — moments when children are on the cusp of a great leap, such as learning to walk, and tend to regress by crying, refusing food or otherwise acting out.

By anticipating and understanding touchpoints, he hoped, parents might be better prepared to confront them — and to celebrate the accomplishments that follow.

“Most issues in parenting involve a spurt in the child’s autonomy and the parent’s need to control,” he told the New York Times. “It helps to see things from the child’s side.”

On the contentious (and often messy) matter of potty training, he advocated what he described as a “child-oriented approach,” saying that parents should allow their youngsters to shed the diaper when they showed signs of readiness, rather than working from a preestablished timetable.

It was a controversial position, opposed by more-conservative parenting experts who lamented permissiveness in parenting. John Rosemond, a child psychologist, advocated what he described as the “naked and $75” method. (The label has resisted inflation.) Parents who employ it keep their child unclothed and within easy reach of a portable potty during training — and set aside $75 to shampoo the carpet.

Dr. Brazelton told the Times that the idea that a child should be housebroken like a puppy was “very logical — for a puppy.”

Some of his views evolved over the years with changing social attitudes. After long arguing that mothers should stay home with young children, he acknowledged in the 1980s that some women needed to work outside the home and found fulfillment in their professions. He credited his transition to his daughters, who he said had told him, “Dad, you are out of this century.”

He became a chief proponent of mandated maternity leave and encouraged working parents to “cheat on the workplace” so they would have the emotional reserves to fully care for their children when they were not on the job. The greatest gift a parent could give, he said, was a loving home from earliest infancy.

“Babies are competent to withstand ‘mistakes’ that their inexperienced parents might make,” he wrote in “Infants and Mothers,” “and even to let the parents know when they are on the wrong track.”

Early on, a way with children

Thomas Berry Brazelton Jr. was born in Waco, Tex., on May 10, 1918. He recalled being distant from his father, who ran the family lumber business but was away for military training when he was born. Dr. Brazelton’s mother served on the local school board and reportedly helped found one of the first abortion clinics in Texas.

Dr. Brazelton said that he “hated” his younger brother because his mother gave him so much attention. He felt closest to his grandmother, who allowed him to look after his many cousins — the experience that he credited with sparking his interest in becoming a pediatrician.

“I’d take care of 11 at a time when my parents and aunts and uncles were outside drinking martinis,” he told the Chicago Tribune. “If you’re taking care of that many kids, you have to learn how to get inside them and manage each one individually.”

Dr. Brazelton graduated from Episcopal High School, a boarding school in Alexandria, Va., before enrolling in Princeton University. There, he performed with the Triangle Club and entertained the idea of entering show business. He said he had a chance to perform in the Cole Porter musical “Panama Hattie,” a Broadway show starring Ethel Merman, but he declined after his family threatened to not finance his medical school if he went forward with it.

He graduated from Princeton in 1940 before receiving a medical degree from Columbia University in 1943, later seeking additional training in child psychiatry under Jerome Bruner. “My goal was to understand human beings, and we were learning mainly about diseases,” he told People magazine in 1982.

Dr. Brazelton began his private practice in 1950 and joined Harvard Medical School the next year.

His books included “Toddlers and Parents: A Declaration of Independence” (1974) and “The Earliest Relationship: Parents, Infants, and the Drama of Early Attachment” (co-written with Bertrand G. Cramer, 1990). In 2003, with Joshua D. Sparrow, he wrote a series of books on parenting “the Brazelton way,” covering topics such as calming a fussy baby, sleeping and discipline. Dr. Brazelton’s memoir, “Learning to Listen: A Life Caring for Children,” was published in 2013.

In 2013, President Barack Obama awarded him a Presidential Citizens Medal, the nation’s second-highest civilian recognition.

His wife, the former Christina Lowell, died in 2015 after 66 years of marriage. Survivors include four children, Catherine “Kitty” Brazelton of New York City, Pauline “Polly” Brazelton of Barnstable, Christina Brazelton of southern Maine, and Thomas B. Brazelton III, also a pediatrician, of Madison, Wis.; and several grandchildren.

Dr. Brazelton’s “simple wish,” he said, was for parents to “have fun with their kids.”

“At age 16 or 17, when my patients have their last exam, I have their charts with bowel movements and spitups and everything in front of me, and I ask them what they remember as children,” he told People. “So many have said, ‘My parents cared so much. They always worried. They never smiled.’ For parenting to be joyless is tragic.”