CAMDEN, N.J. — Jernica Quiñones, a mother of five, was the first parent in New Jersey to get her free baby box — a portable, low-tech bassinet made of laminated cardboard. But first, she had to take an online course about safe sleeping practices, which experts say can sharply reduce the chances of sudden infant death syndrome.

“Basically, you want to have the baby on the mattress, and that’s it,” she said after watching a 20-minute series of videos.

The message may not be new. But health officials say it is critical to keeping babies safe. To reduce infant mortality, parents must put babies to sleep on their backs on a firm mattress in either a bassinet or a crib — with no pillow, blanket, stuffed animal or bumpers.

Now, New Jersey has become the first state to adopt a broad program to reduce infant deaths by aiming to distribute as many as 105,000 of the so-called baby boxes — the expected number of births in the state this year. Baby boxes, which have a snug-fitting mattress, have been handed out to new parents for decades in Finland, which has one of the lowest infant mortality rates in the world, and less than half that of the United States.