Lucy never quite gets a moment to tell Ricky that she is pregnant.
This intallment is a little different in that generally Lucy schemes to get away with a plan, and here, the audience is hoping that she gets the chance to tell the truth of a situation. It works well as a story, the viewer actually gets invested more in the story the way it's scripted. The oft-used device of almost getting to the truth but not quite is effectively acted by Ball and Arnaz.
Though "I Love Lucy" was filmed, there are good examples here of the production team letting the first and more emotional take stand. Ricky actually flubs the lyrics of "Rock-A-Bye-Baby" and there is genuine sentiment in the night club scenes that appear less rehearsed and less slickly done. These things combine to make this a definite "feel good" and surprising episode for those who first watched it. One of those that deserves to be remembered over the decades.