Yolanda Litz remembers her first flash of “grandmotherhood.” Her daughter was expecting, all was going well, “when I got this little seed in my brain. What if our first grandchild needs us?”

What indeed! Litz took action, quit her salon job as a skin aesthetician and became an independent contractor and part-time grandmother-sitter just in time to learn new rules for bringing up baby.

New research, new attitudes and new products have turned baby care topsy-turvy in the past 15 years.

Millions of grandparents provide child care for grandchildren on a daily or weekly basis, 3 million grandparents live with adult children and grandchildren and 1.4 million grandparents have direct custody of 4 million grandchildren, experts say.

Yet a recent survey of 774 grandparents found that most don’t have the latest information on children and child development, leading to significant knowledge gaps, says Civitas Initiative, a Chicago-based child-advocate group.

Instinct still tops all, but safety concerns and the emerging field of infant development have transformed the first year of a child’s life from just keeping baby comfy to mandated car seats and Mozart in the crib.

“Sometimes I wonder how I raised my three kids,” says the Lake Forest, Calif., grandmother. Litz cares for Sophia, now 8 months, about once a week.

“The big thing I had to learn was to put her on her back (to sleep), not her stomach. We always kept our kids on their stomachs so they wouldn’t choke, but no more.”

What worked in the past, what was family tradition, goes by the wayside, Litz complains.

She saved her children’s crib, for example, but the slats are too far apart by today’s safety standards. “I may just use it anyway and tie a big bumper around it,” she says.

While experts warn about various ways babies can be harmed in older cribs, Litz dismisses the concern: “There is a thing as too much information information overload.”

She puts up with Sophia riding backward in the back seat car seat required until babies are 20 pounds or 1 year old but resents not being able to see her. Litz took her children to the beach and let them run around naked. Now experts advise protecting babies from the sun but warn against using sunblock before six months.

Basic grandmothering remains important, however, Litz says. “I find I’m not as concerned about having everything ‘just so’ in the house. I play with Sophia. I find myself letting her play with things I wouldn’t let her mother do like play with her food.”

Playing with food is a good thing, says Diane Golden. She should know. She has raised three of her own children and taught basic baby care at St. Jude and St. Joseph hospitals in Orange County, Calif., for 22 years.

Golden tells mothers to hold their babies, to comfort them whenever they cry.

“That’s a big change from the way we were told to raise our children 25 years ago,” she concedes.

Nuzzling is the joy of grandparenting, says Los Angeles publicist Judi Davidson. She and her husband, Gordon Davidson, artistic director of the Ahmanson Theatre and Mark Taper Forum, enrolled in a basic baby-care class to become modern grandparents.

“We’re so flattered to be asked to care for our granddaughter,” says Davidson, mother of two. “But we had so much to learn!”