While it seems like Glee writers have not delved into Quinn’s pregnancy, it is by design and not by ignorance.
“In the first 13 episodes, we had way too much baby drama with Terri and the fake baby,” said series creator Ryan Murphy, “so one of the things we’ve pulled back from is the pregnancy story. Quinn’s clearly pregnant, but….she has other things going on. We don’t go overboard on it anymore.”
It is confirmed that she will, however, give birth in the show’s season finale.