Babies born at 22 weeks

So our son is currently 22 weeks... I started watching these videos of babies born prematurely. I watched one of a 18 week old that was miscarried, but you could still see the chest rising and falling. :-( 
But then I watched a video of twins born at 22 weeks old and they survived. I didn't realize that they could survive so young outside of the womb! If you want to see the video, check it out...
https://m.youtube.com/watch?v=5q1YVFHIA8E