Breast-feed your baby. Breast milk contains turbo-charged immunity-enhancing antibodies and white blood cells. Nursing guards against ear infections, allergies, diarrhea, pneumonia, meningitis, urinary-tract infections, and sudden infant death syndrome. Studies show that it may also enhance your baby's brain power and help protect her against insulin-dependent diabetes, Crohn's disease, colitis, and certain forms of cancer later in life. Colostrum, the thin yellow "premilk" that flows from the breasts during the first few days after birth, is especially rich in disease-fighting antibodies, says Dr. Shubin. The American Academy of Pediatrics recommends that moms breast-feed for a year. If this commitment isn't realistic, aim to breast-feed for at least the first two to three months in order to supplement the immunity your baby received in utero.