(No, not on a rating system of who’s hot and who’s not; this rating system goes back a lot further.)
In the olden days when I was growing up, infants born before full gestation were called preemies, short for premature. (Now they’re called neonates, we advance, at least in vocabulary.) Anyway, I had a great aunt who legendarily sent her son off to kindergarten bearing a note for the teacher which read: “Please be careful with my Jake, he’s a Seven.”
The teacher was puzzled: according to her records, Jake was six. And anyway why should she be especially careful of a six- or a seven-year-old?
But the next week Jake brought another note: “Be careful, Jake is a Seven,” and she decided to find out what it meant. Whether she went to my aunt’s house, or my great aunt went to the school, the legend doesn’t tell. But they met, and the teacher learned that Jake had been born in the seventh month of my great aunt’s pregnancy, and as everybody knew, a baby born that early is unusually delicate; and my great aunt learned that in America a premature baby is not usually called a Seven.
And certainly not a Six, or Four, or Two: such neonates rarely or never survived in those days.
It’s different now (see A Rescuing Hug), when it’s pretty much expected that such babies will grow up just fine. Well, maybe yes and maybe no: there can be multiple problems with such tiny newborns at the time and even for years afterward. The Rescuing Hug story had a happy ending. But sometimes the need for special care is if anything more vital than back in the day when my great aunt cautioned Jake’s teacher, “Be careful, because Jake is a Seven.”