A research group from Germany, which studied nearly 2,200 children found that babies who stay out of the pool until after their first birthday obtained substantially less sicknesses such as diarrhea, respiratory and ear infections then children who were taken swimming regularly before their first birthday.   The leading cause for these illnesses was do to the child digesting, inhaling and having water stuck in their ears.   Even though the water may be clean, a baby’s immune system is still developing which provides children under the age of one a greater chance to get sick.  If you are considering baby-swimming classes try to wait until your child is at least a year old.  If you want to take your baby swimming on rare occasions, judging by this study it should be fine; however, try to make sure your baby’s head does not get submerged in water.