As an aside, i'd be surprised if most of the profile pictures are of older children.
When I had two under two I was subsumed by motherhood, I was fucking knackered - no family nearby, no childcare for either of them. I had absolutely no energy to do anything for myself.
Now they're two and four I go to the gym, sing in a choir, volunteer for a charity. But two years ago, my kids basically were the sum total of my life. I'd happily put my photo on now - two years ago, a photo of me knackered, overweight, to present myself to the world? No thanks.
Is it such a terrible thing to give a few years over to early childhood and pick up where you left off a bit later? It makes me really cross that people think it's wrong to concentrate on your children when they're tiny.