The writers of CBS’ “The Big Bang Theory” faced a particular challenge this season: giving birth.

Melissa Rauch’s Bernadette, wife of Simon Helberg’s Howard Wolowitz, has been in the family way and will finally deliver baby Wolowitz in the Dec. 15 episode, “The Birthday Synchronicity.” The result is a heart-tugging episode revolving around a milestone moment in the lives of the “Big Bang” gang — without veering into treacly territory.

“Big Bang” showrunner Steven Molaro jokes that Bernadette has actually been pregnant for about 11 months in the timeline of the show. As planning for season 10 of the Warner Bros. TV series began last summer, “We figured she ought to have this baby pretty soon,” he says.

In preparing for the big day, the scribes were determined to avoid what have become sitcom cliches — the mother screeching in the stirrups, the father fainting in the delivery room. The solution was to mostly avoid depicting the birth itself to focus on how the arrival of baby Wolowitz impacts the rest of the ensemble: Sheldon (Jim Parsons), Amy (Mayim Bialik), Leonard (Johnny Galecki), Penny (Kaley Cuoco), Raj (Kunal Nayyar) and Stuart (Kevin Sussman).

“Birthday Synchronicity” was penned by Molaro, Eric Kaplan and Tara Hernandez from a story by Chuck Lorre, Steve Holland and Maria Ferrari. Nikki Lorre, daughter of the series co-creator/exec producer, directed the episode, marking her third helming assignment on “Big Bang” to date.

Molaro is mindful that childbirth has often been seen as a jump-the-shark moment for long-running series. “Big Bang” plans to carefully manage the volume of kid-centric stories that arise for Howard and Bernadette.

“We view (the baby) as another opportunity to grow our universe and find more stories that allow these characters to grow,” Molaro says. “We don’t see it as a giant DNA-changing event in what ‘The Big Bang Theory’ is.”

Molaro jokes that the Wolowitzes’ will have ample help in taking care of the baby, freeing Howard and Bernadette to keep up their usual antics.

“We’re still going to have Ladies Night. All the things we love about the show can keep happening, in addition to baby stories when we want do them,” Molaro says.

In Thursday’s episode, the Wolowitzes’ big day winds up landing on Amy’s birthday. As fans of “Big Bang” remember from last year’s much-praised “The Opening Night Excitation,” Amy’s birthday invokes her annual date for intercourse with Sheldon — albeit with some complications this time around.

Molaro took one element of the Wolowitzes’ birth story from his real-life experience with his first child. Molaro and his wife set out to be surprised by their baby’s gender, but that cliffhanger was spoiled by an uncooperative key player in the process.

One of the poignant moments of “Birthday Synchronicity” comes as Howard speaks from the heart about missing his own mother. The actress who played the perpetually unseen Mrs. Wolowitz, Carol Ann Susi, died in 2014. Pamela Adlon, of FX’s “Louie” and “Better Things,” who was a friend of Susi’s, has a guest shot in the episode to pay fitting tribute to baby Wolowitz’s grandmother.

“For the actors it wasn’t hard to tap into the feeling of loss because we were all feeling it for Carol,” Molaro said.

After this week, “Big Bang” takes a breather from new episodes until Jan. 5. The first episode of 2017 features a return guest appearance by Laurie Metcalf as Sheldon’s Bible-thumping mother in a story that finds the core couples recounting their respective holiday experiences.