Myth My child doesn't sleep well, so he won't grow.
Reality Kids need rest to thrive; their body releases growth hormone during sleep. But even if your child refuses to nap or wakes often at night, he's likely getting enough sleep to grow. If your child is a snorer or a mouth breather or pauses in his breathing when asleep, tell your doctor. These are signs of sleep disordered breathing, a treatable condition affecting about 20 percent of kids.
Myth Your child's weight and height percentiles should match.
Reality Not necessarily, says Parents advisor Ari Brown, M.D., author of Baby 411. "But you don't want your child's weight to be in the 75th percentile and her height in the 10th, since that may indicate she's headed for a weight problem later in life."
Myth Big babies grow into big kids.
Reality "Having a large baby is often just a sign that everything went well during your pregnancy," says Daniel Rauch, M.D., associate professor of pediatrics at Mount Sinai School of Medicine, in New York City. (Your baby may have also been uncharacteristically big if you suffered from gestational diabetes.) But once he's out of the womb, genetics take over, and unless he's got supersize parents, he'll show his true growth patterns between 9 and 18 months.