Baby before marriage

Ladies, I might not understand something, but please explain to me: why do so many of you TRY to get pregnant before marrying the guy? I have heard so many horror stories about that "serious boyfriend" or "darling fiancé" disappearing after they get the girl impragnated. Don't you want solid guarantees that this man is a good man before having a kid with him? I am 23 years old, have been married for 2.5 years and just got pregnant because I am now sure of my husband. Am I too old fashioned?