What is the best age to start children for swim classes ? Baby , toddler or preschoolers?

There are different schools of thought here. Some say that you should let kids in water as early as a few months old. They have natural reflexes from staying in the mother's womb surrounded by amniotic fluid and aren't scared of water yet. However, studies suggest that kids who learn swimming before 3 years of age are at greater risk of being careless in and around water. Doctors all around the world also suggest that kids be at least 3 year old before starting swimming lessons.