Experts at Parents' 10 best children's hospitals fill you in on their latest research to prevent children from getting sick or hurt. Take some notes.

The right time to change seats "Don't switch your toddler to a booster if he still fits in his car seat with the five-point harness. While boosters are great for school-age kids, younger ones may wiggle around, so the seat belt may not be in the best position if they were in a crash."

-- Gina Duchossois, trauma prevention coordinator, The Children's Hospital of Philadelphia

Try to tone it down "Loud toys may cause hearing loss. Since kids tend to hold their toys very close to their ears, buy ones that have volume control.

-- Roanne Karzon, PhD, manager of audiology at St. Louis Children's Hospital

When to skip the helmet "If your child is riding his bike at the park, tell him to take off the helmet if he stops at the playground. It can get caught on the equipment."

-- Gary Smith, MD, director of the Center for Injury Research and Policy at Nationwide Children's Hospital, Columbus, Ohio

A vaccine for the whole family "Since babies aren't protected from whooping cough until they get their third vaccine at their 6-month checkup, the best way to prevent this infection is to vaccinate everyone else in your house."

-- C. Mary Healy, MD, director of Vaccinology and Maternal Immunization, Texas Children's Hospital, Houston

The unknown choking hazard "Cut your child's grapes in half until she's 4 years old. Our study found that four in 10 parents mistakenly thought it was fine to give whole grapes to 1- to 3-year-olds."

-- Harold K. Simon, MD, emergency medicine physician at Children's Healthcare of Atlanta

The best milk for your toddler "If you have a strong family history of obesity or heart disease, give your 1-year-old reduced-fat milk rather than whole milk."

-- Stephen Daniels, MD, PhD, pediatrician in chief at the Children's Hospital, Denver