After this first season's success, Big Finish began producing audio stories and prose stories simultaneously. These were initially released alternately so that both the audio and the prose (novel and short story) made up the Bernice Summerfield series, with some of the wider arc story only being featured and explained in detail in one medium. Bernice's pregnancy was one such occurrence which began in the novel The Gods of the Underworld and she gave birth in the novel The Glass Prison with minor references to the actual pregnancy in audio stories released around the same time. However, this practice ceased after the third series.