We used pull out for 4 years with no pregnancies. now i'm pregnat even when he pull out and there were no "second round" or masturbantion before. how?

That's how it is: The "pull out" method is not very reliable birth control, because some sperm can come out and create a cute little baby, even with no ejaculation. This happens every day, all over the world... but happens only once in a while to each particular couple. That means, after delivery, one should use a more reliable form of birth control if not wanting another baby.