Why do people call their children this??!!

Can someone please explain to me why moms call their kids or child "the littles" seriously why?? I don't get it and I'm sorry but it sounds really confusing too because myself as well as other friends have been like "are they talking about another couple with the last name little" that and it just sounds kind of dumb. Lol can't you just call them by their names or just say "my kids" or somethings like that?? Lol I dunno it's just one of those phrases that gets under my skin, lol you know like how people are with the word "moist" or "ointment" loL
Update! "little one" is fine for me to hear and I even say, that's phrase is no bother to me I just find it a really cheesy and odd sounding phrase