A big storyline such as the 'Wolobaby' needs to be done correctly, not rushed. Leonard and Penny's final decision to get married and the wedding itself was an enormous disappointment considering it was anticipated since the very beginning of the show. The writers could waltz their way through to the end of this season before using a leap in time to Bernadette going into labour. I doubt they would... But they certainly could, and certainly shouldn't. Pregnant Bernadette could be an amazing source of laughs and adds a completely different angle for the entire show to benefit from.