Babies need space to spread out in order to grow. Variation: Your baby will be crooked unless you keep his back perfectly straight in a stroller.
I have to believe this arose from a gardener. Plants that are given more space grow better and if you let them bend for too long, they stay that way. Uh, yes, except that babies are not rosebushes.
They are baby mammals whose most pleasant experience to date (perhaps ever) is in the tight warm confines of mama’s belly and then her arms. And a happy baby grows better – ever notice all those indigenous mothers with baby tied to them? Ever notice how happy those babies look all squished inside their pretty wraps? Funny – there don’t seem to be millions upon millions of stunted, crooked villagers all over the world.
Arms tired? Ah, perhaps your little one is growing (phew!). Get yourself one of those lovely slings and carry on.