Infection. Diaper rashes that won't go away are frequently caused by a yeast infection. Your baby's diaper is a warm, wet environment that draws yeast, which can lead to illness. Diaper rash is frequently caused by the fungus Candida albicans (the medical word for yeast). It spreads easily from skin to skin, hair to hair, and fabric to fabric if you don't wash your clothes properly. Yeast infections are common in babies and children of all ages. They can be brought on by stress, antibiotics, colds, stomach bugs, and other illnesses. The more likely cause is a problem with the body's balance of bacteria, called the gut flora. When the gut flora is out of balance, yeast can grow out of control and cause problems. Babies' bodies are not ready for such a large amount of sugar at such an early age. Breast milk or formula that contains sugar can quickly lead to tooth decay and other health issues for your baby. Here are some tips for preventing yeast infections: • Wash your hands often with soap and water or use an alcohol-based hand sanitizer. This will help prevent spreading yeast throughout your house. • Don't share objects that have been in contact with your baby's body with others. This includes diapers and wipes. • Change your baby's diaper as soon as he or she shows signs of needing to go number two.