Yeast infection can affect not only adults but children and babies as well. Probably the most common baby yeast infection is oral yeast infection or thrush. The most obvious symptom consists of small white patches on the inner walls of the mouth, gums or tongue. These can be very painful and irritating, and the baby often cries and cannot eat, drink or suck properly. Unless treated at once, this condition can interfere with the baby’s nutrition and sleeping patterns, and may lead to slow weight gain. Other forms of yeast infection can also affect babies, especially in the diaper area where bacteria thrive due to the warmth and wetness. Antibiotics that children take when they are sick can also make them prone to baby yeast infection.