孩児 is read as がいじ (gaiji) and means infant.
がいじ
gaiji
しょうがいじ
child
しょうじ
young child
いくじ
childcare
こ
-er (often of young women)
こじ
orphan
ようじ
child over 1 but not yet of school age
にゅうじ
infant (below 1 year old)
そうせいじ
twins
じょじ
girl
しんせいじ
newborn baby
だんじ
man
いじ
abandoned child