I have always enjoyed being young and teaching high school because I've felt it's given me an edge on the connecting-with-your-kids factor. In fact, until this year's freshmen crop (I believe) I've even been in the same Millennial generation as my students! But I've also always known that was a temporary advantage. Because no matter how hard I try, I get older every day. And nothing ages you more than going through a stage of life. I'd certainly call having a baby a qualifier for a stage of life.
I was reminded of this defeat against time when I told my students I'd just be teaching two classes each afternoon and they thought that was so cool because I could sleep in all morning. I laughed and explained that's not exactly life with a baby.