And this, I have to say, is the reason why I would never risk a child - 3rd or 2nd or even 1st - past the age of 40. I could not cope. I would not cope. I wouldn't want to try to cope. I don't know how people do it, I really don't. We have 2 healthy NT children, (couple of years apart in age,) and for the most part they've been good kids/ARE good kids (now in their 20s.) Both left home now and totally independent.
But even with 2 like this, it's been quite hard work sometimes, not without its challenges, and expensive. We would not change a thing, ever, and love them to the moon and back, and they are wonderful, successful, kind young adults now who bring so much joy to our lives, and are great friends to us. But as I said, it's had its challenges and trials and tribulations. (Especially when they were between 14-15 and 20. A special kind of hell!)
All the spats and fights with other kids at school, (and their parents,) 12-13 years of school politics, fighting over toys and gadgets/wanting one each, the expense, 2 sets of clothes and school uniform and supplies, 2 small humans being totally dependant on you for everything, being mum's taxi and ferrying them everywhere, entertaining and tolerating their mates (who seemed to LOVE our house!,) and putting 2 young adults through uni, and the expense that entailed. That's just the tip of the iceberg! We have the expense of their weddings yet! I mean, we won't be paying for all of it, but we will be paying quite a lot.
Now we are aged 50-something with 2 young adult children who have left home, and we are very happy. All of us. I can't imagine having children who need a lot of care, and 24/7 demands, and to have no life to ourselves. And there would be no end to it, as children like this need care all their lives.