So if researchers don't agree on why—or even whether—girls are developing earlier, what's a parent to do? "If you had to pick one thing you could do as a parent, it's to choose a healthy diet and encourage exercise," says Ora Pescovitz, MD, director of the pediatric endocrinology division at Indiana University School of Medicine. "We're eating too much in general, and too many high-fat and simple-carbohydrate foods."

Most of the following suggestions from our panel of experts offer intrinsic health benefits—even if they don't prove to alter the rate of your daughter's development:

  • Encourage children to engage in active play, athletics, and exercise.

  • Offer healthy foods that do not promote excessive weight gain. These include complex carbohydrates and fresh fruits and vegetables.

  • Limit exposure to plastics in the kitchen, and do not microwave in plastic.

  • Minimize children's contact with plastic toys, especially infants, who tend to mouth everything. Or use cloth toys instead.

  • Eat organic produce, meat, and dairy products. Wash all fruit and vegetables well or peel before eating.

  • Wash your hands and your children's hands often to minimize ingestion of chemicals.

  • Cut down on the use of makeup, nail polish, and hairstyling products if you are pregnant or could be soon.

  • Do not use herbicides or toxic pesticides on your garden and lawn.

—D.S.B.