Tim Minear says this episode is fundamentally about "body horror." Originally, it was written in a more comedic style, but Joss Whedon insisted the writers "should play [it] straight." Minear says this episode begins to show Wesley as being "more than he appeared to be on Buffy", as well as demonstrating that the members of Angel Investigations are forming a family.
At the OB-GYN, Wesley and Cordelia are pretending to be Mr. and Mrs. Pangborn. This appears to be an homage to science fiction writer Edgar Pangborn (1909-1976), who is famous for his classic novelette "Angel's egg" (1951). (See also Angel's Egg (1985).)
This episode is the first time that we see Dennis object to an unwelcome entity in Cordy's apartment. It is also the first time we see him make caring gestures (e.g., offering a tissue, tucking up her covers) instead of annoying ones (e.g., sliding her soda when she's on the phone).
In the conversation between Cordelia and Angel at the end of the episode, she lists what she learned from her impregnation experience: "I learned, um, men are evil? Oh wait, I knew that. I learned that L.A.'s full of self-serving phonies? Nope, had that one down, too. Uh, sex is bad?" Angel agrees, "We all knew that." referencing the loss of his soul following sex with Buffy in Surprise (1998).
The bonds of trust and friendship deepen significantly among Angel, Cordelia and Wesley. When the bartender at La Brea asks if Angel is "the boyfriend," Angel replies, "No. I'm family."