In "The Valentino Submergence", Howard and Bernie nurse a rabbit back to health that almost drowned in their hot tub looking very parental while doing it. After Howard heads to the emergency room, Bernadette tells the rabbit that she'll have to find another time to tell Howard that she's expecting. The rabbit didn't die, but that is also a cliche for being pregnant.
In "The Birthday Synchronicity", Bernadette gives birth and Howard announces that she had a girl. The baby is named Halley. Also it's Amy's birthday. The baby was named after Halley's Comet. Her cry is sounded like Mrs Wolowitz screaming.
In "The Holiday Summation", Halley is crying constantly and Bernadette doesn't know how to deal with it. She gets more upset when Stuart gets her to stop very quickly. Finally she solves the problem by crawling into Halley's crib and holding her while she sleeps.
Green = Appeared, V = Voiced, C = Cameo, F = Flashback, M = Mentioned, Dark Grey = Did not appear, Black = Not aired/Not available