Klaas went for his 4-month checkup last week. He now weighs 18 lb, 6 oz and is 26.5 inches long. We have a huge son. Who also knows how to flip himself all over now. He can roll back to stomach now. I need to look up when Hazel did this, but I want to say she was at least 6 months old. So having such a mobile babe is new for us. He's become an expert at kicking himself out of his bouncy chair when he's done with that activity. Only to find himself just lying uncomfortably half on the floor and half on the chair, wondering what to do next. It's only a matter of time until this guy is crawling.