Not long ago, Kathleen Todd-Seymour, a pediatric registered nurse who runs an agency called Mother & Child Postpartum Care, arrived at a client’s home to find the mother waiting at the door, her infant crying in her arms and the mother close to tears herself. The baby had been crying for hours. ”I don’t know what to do with him,” she said.

”Have you tried to swaddle?” Todd-Seymour asked.

”But it’s not sleep time,” said the mother, clearly frustrated.

Todd-Seymour tells that story as a reminder of how easy it is for even the most loving parents and caregivers to slip into that dangerous zone that can lead to shaken baby syndrome, which is responsible for two to four infant deaths a year in Massachusetts and about 1,500 nationwide.

”Swaddling isn’t just about sleep,” Todd-Seymour told the mother. ”It’s about calming a baby.”

She might have added: and a parent.

Working on the theory that a parent or caregiver who knows how to soothe a baby is less likely to reach a point of frustration that could lead to fatal shaking or debilitating injury, Massachusetts Citizens for Children is sponsoring two daylong seminars for child-care professionals with UCLA pediatrician Harvey Karp — the author of the best-selling ”The Happiest Baby on the Block” and ”The Happiest Toddler on the Block,” which have been made into DVDs. Today’s session is at the Days Inn in Chicopee, and tomorrow’s is at the Bentley College Conference Center in Waltham.

Jetta Bernier, executive director of Massachusetts Citizens for Children, hopes Karp’s soothing methods will be incorporated into a $675,000 statewide initiative to train health care providers in child abuse prevention. The initiative, whose approval is anticipated in the legislature, would include in-hospital presentations to parents of newborns. It is modeled on a shaken baby syndrome prevention initiative that MCC runs in Worcester and Hampden counties. If it is adopted, Massachusetts will be the first state to incorporate Karp’s methods in a child abuse prevention plan.

”From a public health perspective, when you have something that is as preventable as this is, it’s a no-brainer,” said Sally Fogerty, associate commissioner for the state Department of Public Health.

The act of shaking a baby can tear fragile blood vessels that link the brain to the skull. Among victims of shaken baby syndrome, about 25 percent die; others suffer moderate to severe brain damage t