Elia S. Parsons wasn’t a doctor, a professor or, at first glance, an expert of any sort. She was a Capitol Hill mom — just the sort of woman to help write “The Mother’s Almanac,” a homespun guide to parenting that changed the genre of child-rearing books after its release in 1975.

Mrs. Parsons, 74, died Dec. 26 at the Maple Ridge assisted living facility in Rockville. She had complications from Alzheimer’s disease, said her daughter Amalia Jones.

Four decades ago, Mrs. Parsons was busy raising her three children when her neighbor Marguerite Kelly came to her with a proposition: to co-write a simple, from-the-heart manual for young mothers such as themselves.

The problem was not that there were too few advice books on the shelves. By the turn of the 20th century, motherhood had been made into a “professional undertaking,” said Ann Hulbert, the author of “Raising America,” which analyzes the history of the country’s parenting advice. Scientific inquiry had led to dogmas, she said, as psychologists offered up definitive approaches to “healthier, smarter, better children.”

The gentlest of all the professionals was Benjamin Spock, the pediatrician who wrote the landmark tome “Baby and Child Care,” first published in 1946. Unlike many other experts, he wrote to mothers in an intimate, sympathetic way and told them not to worry. But even he was a doctor — and a man, not a mom.

Mrs. Parsons and Kelly wanted to write a book that would “de-escalate the idea that you have to be an expert to raise a child,” Mrs. Parsons once said.

The guide would begin with pregnancy and end around the child’s sixth birthday. It would be stocked with reassurances about the day-to-day problems of motherhood, from tantrums to fevers, and insightful counsel about greater difficulties, such as divorce and death.

Katharine E. Zadravec, author of The Washington Post’s longtime column Anne’s Reader Exchange, wrote of “The Mother’s Almanac” when it first appeared: “If motherhood is an art that can be mastered, Marguerite Kelly and Elia Parsons have produced a good ‘how, when and why’ guide to that art. You supply the patience and talent, and you’re all set.”

The two women never could have expected that their almanac would sell more than 800,000 copies, or that it would signal a fundamental shift in the publishing industry. “What to Expect When You’re Expecting” — one of the most popular of all the by-moms-for-moms books that followed “The Mother’s Almanac” — has sold 17 million copies since its release in 1984. Kelly writes a parenting column for The Washington Post and has authored sequels to the almanac.

Back in the early 1970s, even publishers apparently didn’t grasp the market for a book such as “The Mother’s Almanac.” When Kelly sent an early outline to Doubleday, an editor told her that she and Mrs. Parsons weren’t qualified to write a guide to child care.

“You have to be a doctor in some field or some kind of expert to do that,” the editor said, according to an account published in The Post in 1975. “You can’t be just a mother.”

Through tears, Kelly explained that she and Mrs. Parsons didn’t envision an important hardcover book, just a paperback on the order of the “Whole Earth Catalog.” Softened, the editor agreed to go forward. The project — including production, which the women arranged themselves — took about five years.

They did the bulk of their work while their children were at school, with Kelly doing the writing and Mrs. Parsons handling the research. She told the New York Times that she spent a year at the Library of Congress “buttressing” their ideas with medical textbooks.

But most of the book came from the women’s experiences as mothers. In its opening pages, they described the happiness from parenthood that “thrusts your spirits higher than the stars” and the sadness that can “rend your soul.”

“One of us knew the lonely agony of waiting out the weeks for a stillborn son and learned to treasure the fullness of life in the midst of its emptiness,” they wrote. They were referring to Mrs. Parsons, who in her fourth pregnancy carried to term a baby who had died in the womb.

When the women wrote about children who play with matches, they were thinking of Mrs. Parsons’s son Ramon.

“Fire stirs such primitive emotions you can expect your child to be fascinated by it and the more it’s forbidden, the more fascinated he’ll be,” they wrote. The passage recounts a trip the Parsons made to the fire station, where Ramon got a talking-to from a firefighter.

“Afterward we . . . said he could strike matches in our presence if the itch ever got too bad. It never did again.”

Many passages, such as one on teaching children how to make up after an argument, were all heart. The women suggested a visit at bedtime, when a child might be willing to “mend the ties.”

“We found darkness sheds a special light on lovers and small children, unlocking words too tender to say by day.”

Elia Esther Sanchez Garcia was born Nov. 8, 1937, in Alvaro Obregon, in the Tabasco region of Mexico. She came to the United States with her family when she was 8, later becoming a naturalized U.S. citizen, and grew up in Evansville, Ind. There, her father was an accountant with a company that sold baby formula.

She received a bachelor’s degree in Spanish and French in 1959 from what is now Dominican University in River Forest, Ill.

One of her early jobs was at the Holt, Rinehart and Winston publishing house in New York, where she wrote definitions for a children’s dictionary.

Her husband, Richard K. Parsons, died in 1990 after 29 years of marriage. Survivors include three children, Ramon Parsons of Manhasset, N.Y., Nadia Richman of Boston and Amalia Jones of the District; a brother; and nine grandchildren.

One of the few faults critics found with “The Mother’s Almanac” was the book’s recommended punishment for foul language: washing out the child’s mouth with soap.

The authors later recanted, writing in an updated edition that they no longer acted “in the manner of [their] foremothers.” But by then Mrs. Parsons had already used the technique on her children.

They survived unscathed, Amalia said.