In India, many people do refer to their children as their wards. Native speakers of English, however, wouldn’t do this. They would consider ‘ward’ to be a legal term; a word that is normally used to refer to a person, especially a child, who is under the legal protection of a guardian or a court of law.
The Collins Cobuild English Dictionary defines a ward as a child who is placed under the care of a guardian because his ‘parents are dead’ or because he is ‘believed to be in need of protection’. Teachers in India sometimes refer to their students as their wards. This would be considered to be rather old fashioned by native speakers.