39 and holding

次ぎの文は確かリーダーズダイジェスト４月号の "Kids: As Kids See it" の記事にあったものです。
My young son was discussing a school health class with my mother, who coquettishly admits to being "39 and holding."
"Grandma," he asked, "have you been through your metamorphosis yet?"
文中の "39 and holding" の表現は最近の流行語「アラフォー」を連想させますがどうでしょうか？
辞書にはこのような用例は見つかりませんでしたがWebsiteには幾らでも用例があります。
・More Magazine always covers these topics but does so with grace and inspiration for the wonderful, beautiful, and confident 40-years-plus women, or the 39 and holding for the umpteenth (http://blog.alc.co.jp/blog/3302827/91050 ) time woman.
・Sorry folks, I didn't ask her age, but she told me she was 39 and holding.
３０代や５０代の年齢
・ I suppose the film might appeal to those 29-and-holding guys out there who can relate to Braff's character, but it's not exactly the kind of film you're going to suggest to your buddies, is it?
・49 and holding... Yep, today I hit 49, and so now the countdown is on to the big five-0 next year.
アラフォーは３５～４５歳程度の女性を指すと聞きましたが、３５～４０歳前半の女性はアラフォーと言われるのは嬉しくなく、アラフォーを自称するのは４５歳以上の方ではないかと推測します。